diff --git a/core/pom.xml b/core/pom.xml
index bc1ccaf..cf471b0 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -136,6 +136,7 @@
                     <!-- how to validate?
                     <include>**/tests/draft2020-12/id.json</include>
                     -->
+                    <include>**/tests/draft2020-12/if-then-else.json</include>
                     <include>**/tests/draft2020-12/items.json</include>
                     <include>**/tests/draft2020-12/maxContains.json</include>
                     <include>**/tests/draft2020-12/maxItems.json</include>
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LINKTYPE.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LINKTYPE.java
new file mode 100644
index 0000000..9b973cb
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LINKTYPE.java
@@ -0,0 +1,44 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.keyword.type;
+
+import jakarta.json.JsonValue;
+import java.util.function.Predicate;
+
+public enum LINKTYPE {
+    VALID {
+        @Override
+        Predicate<JsonValue> connect(final Predicate<JsonValue> first, final Predicate<JsonValue> second) {
+            return first.negate().or(second);
+        }
+    },
+    INVALID {
+        @Override
+        Predicate<JsonValue> connect(final Predicate<JsonValue> first, final Predicate<JsonValue> second) {
+            return first.or(second);
+        }
+    };
+
+    abstract Predicate<JsonValue> connect(Predicate<JsonValue> first, Predicate<JsonValue> second);
+}
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeyword.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeyword.java
new file mode 100644
index 0000000..102d13b
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeyword.java
@@ -0,0 +1,70 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.keyword.type;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.JsonValue;
+import java.util.Collection;
+import java.util.EnumSet;
+import java.util.Objects;
+import java.util.Set;
+
+final class LinkedKeyword implements Applicator {
+
+    private final Keyword firstChainLink;
+    private final LINKTYPE linkType;
+    private final Keyword secondChanLink;
+
+    public LinkedKeyword(final Keyword firstChainLink, final LINKTYPE linkType, final Keyword secondChanLink) {
+        this.firstChainLink = Objects.requireNonNull(firstChainLink);
+        this.linkType = Objects.requireNonNull(linkType);
+        this.secondChanLink = Objects.requireNonNull(secondChanLink);
+    }
+
+    @Override
+    public Collection<KeywordCategory> categories() {
+        final Set<KeywordCategory> result = EnumSet.copyOf(firstChainLink.categories());
+        result.addAll(secondChanLink.categories());
+        return result;
+    }
+
+    @Override
+    public boolean applyTo(final JsonValue instance) {
+        return linkType
+            .connect(firstChainLink.asApplicator()::applyTo, secondChanLink.asApplicator()::applyTo)
+            .test(instance);
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return secondChanLink.hasName(name);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return secondChanLink.printOn(media);
+    }
+}
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWith.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWith.java
new file mode 100644
index 0000000..5b4c1ae
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWith.java
@@ -0,0 +1,77 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.keyword.type;
+
+import io.github.sebastiantoepfer.jsonschema.JsonSchema;
+import io.github.sebastiantoepfer.jsonschema.JsonSubSchema;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import java.util.Objects;
+import java.util.function.Function;
+
+public final class LinkedWith implements AffectedBy {
+
+    private final String name;
+    private final Function<JsonSubSchema, Keyword> keywordCreator;
+    private final LINKTYPE linkType;
+
+    public LinkedWith(
+        final String name,
+        final Function<JsonSubSchema, Keyword> keywordCreator,
+        final LINKTYPE linkType
+    ) {
+        this.name = Objects.requireNonNull(name);
+        this.keywordCreator = Objects.requireNonNull(keywordCreator);
+        this.linkType = Objects.requireNonNull(linkType);
+    }
+
+    @Override
+    public Function<Keyword, Keyword> findAffectedByKeywordIn(final JsonSchema schema) {
+        return schema
+            .subSchema(name)
+            .map(keywordCreator)
+            .map(k -> (Function<Keyword, Keyword>) new KeywordLink(k, linkType))
+            .orElse(ReplacingKeyword::new);
+    }
+
+    @Override
+    public String toString() {
+        return "LinkedWith{" + "name=" + name + '}';
+    }
+
+    private static class KeywordLink implements Function<Keyword, Keyword> {
+
+        private final Keyword firstChainLink;
+        private final LINKTYPE linkType;
+
+        public KeywordLink(final Keyword firstChainLink, final LINKTYPE linkType) {
+            this.firstChainLink = Objects.requireNonNull(firstChainLink);
+            this.linkType = Objects.requireNonNull(linkType);
+        }
+
+        @Override
+        public Keyword apply(final Keyword secondChanLink) {
+            return new LinkedKeyword(firstChainLink, linkType, secondChanLink);
+        }
+    }
+}
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/ReplacingKeyword.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/ReplacingKeyword.java
index 39d5a61..25e0a33 100644
--- a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/ReplacingKeyword.java
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/ReplacingKeyword.java
@@ -38,7 +38,7 @@
 import java.util.List;
 import java.util.Objects;
 
-final class ReplacingKeyword implements Keyword {
+public final class ReplacingKeyword implements Keyword {
 
     private final Keyword keywordToReplace;
     private final Collection<KeywordCategory> categoriesToReplace;
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabulary.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabulary.java
index 15a9b37..a0c6015 100644
--- a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabulary.java
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabulary.java
@@ -28,16 +28,21 @@
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.Affects;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.AffectsKeywordType;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.ExtendedBy;
+import io.github.sebastiantoepfer.jsonschema.core.keyword.type.LINKTYPE;
+import io.github.sebastiantoepfer.jsonschema.core.keyword.type.LinkedWith;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.NamedJsonSchemaKeywordType;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.ReplacedBy;
+import io.github.sebastiantoepfer.jsonschema.core.keyword.type.ReplacingKeyword;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.SchemaArrayKeywordType;
 import io.github.sebastiantoepfer.jsonschema.core.keyword.type.SubSchemaKeywordType;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
 import io.github.sebastiantoepfer.jsonschema.keyword.KeywordType;
 import io.github.sebastiantoepfer.jsonschema.vocabulary.spi.ListVocabulary;
 import jakarta.json.Json;
 import jakarta.json.JsonValue;
 import jakarta.json.spi.JsonProvider;
 import java.net.URI;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Optional;
 
@@ -58,6 +63,21 @@ public ApplicatorVocabulary(final JsonProvider provider) {
             new SchemaArrayKeywordType(AllOfKeyword.NAME, AllOfKeyword::new),
             new SchemaArrayKeywordType(AnyOfKeyword.NAME, AnyOfKeyword::new),
             new SchemaArrayKeywordType(OneOfKeyword.NAME, OneOfKeyword::new),
+            new AffectedByKeywordType(
+                ThenKeyword.NAME,
+                List.of(new LinkedWith(IfKeyword.NAME, IfKeyword::new, LINKTYPE.VALID)),
+                new SubSchemaKeywordType(ThenKeyword.NAME, ThenKeyword::new)::createKeyword
+            ),
+            //if keyword as no meanings without then or else -> needs a better affects keywordtype
+            new SubSchemaKeywordType(
+                IfKeyword.NAME,
+                schema -> new ReplacingKeyword(new IfKeyword(schema), EnumSet.allOf(Keyword.KeywordCategory.class))
+            ),
+            new AffectedByKeywordType(
+                ElseKeyword.NAME,
+                List.of(new LinkedWith(IfKeyword.NAME, IfKeyword::new, LINKTYPE.INVALID)),
+                new SubSchemaKeywordType(ElseKeyword.NAME, ElseKeyword::new)::createKeyword
+            ),
             new SubSchemaKeywordType(NotKeyword.NAME, NotKeyword::new),
             new NamedJsonSchemaKeywordType(PropertiesKeyword.NAME, PropertiesKeyword::new),
             //nomally affectedBy ... but we had the needed function only in affects :(
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeyword.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeyword.java
new file mode 100644
index 0000000..5338662
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeyword.java
@@ -0,0 +1,67 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.jsonschema.JsonSchema;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import jakarta.json.JsonValue;
+import java.util.Objects;
+
+/**
+ * <b>else</b> : <i>Schema</i><br/>
+ * When if is present, and the instance fails to validate against its subschema, then validation succeeds against this
+ * keyword if the instance successfully validates against this keyword’s subschema.<br/>
+ * <b>kind</b>
+ * <ul>
+ * <li>Applicator</li>
+ * </ul>
+ *
+ * source: https://www.learnjsonschema.com/2020-12/applicator/else/
+ * spec: https://json-schema.org/draft/2020-12/json-schema-core.html#section-10.2.2.3
+ */
+class ElseKeyword implements Applicator {
+
+    static final String NAME = "else";
+    private final JsonSchema schema;
+
+    public ElseKeyword(final JsonSchema schema) {
+        this.schema = Objects.requireNonNull(schema);
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return Objects.equals(NAME, name);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return media.withValue(NAME, schema);
+    }
+
+    @Override
+    public boolean applyTo(final JsonValue instance) {
+        return schema.validator().isValid(instance);
+    }
+}
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeyword.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeyword.java
new file mode 100644
index 0000000..23fbf9b
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeyword.java
@@ -0,0 +1,67 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.jsonschema.JsonSchema;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import jakarta.json.JsonValue;
+import java.util.Objects;
+
+/**
+ * <b>if</b> : <i>Schema</i><br/>
+ * This keyword declares a condition based on the validation result of the given schema.<br/>
+ * <br/>
+ * <b>kind</b>
+ * <ul>
+ * <li>Applicator</li>
+ * </ul>
+ *
+ * source: https://www.learnjsonschema.com/2020-12/applicator/if/
+ * spec: https://json-schema.org/draft/2020-12/json-schema-core.html#section-10.2.2.1
+ */
+final class IfKeyword implements Applicator {
+
+    static final String NAME = "if";
+    private final JsonSchema schema;
+
+    public IfKeyword(final JsonSchema schema) {
+        this.schema = Objects.requireNonNull(schema);
+    }
+
+    @Override
+    public boolean applyTo(final JsonValue instance) {
+        return schema.validator().isValid(instance);
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return Objects.equals(NAME, name);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return media.withValue(NAME, schema);
+    }
+}
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeyword.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeyword.java
new file mode 100644
index 0000000..294e40b
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeyword.java
@@ -0,0 +1,68 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.jsonschema.JsonSchema;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import jakarta.json.JsonValue;
+import java.util.Objects;
+
+/**
+ * <b>then</b> : <i>Schema</i><br/>
+ * When if is present, and the instance successfully validates against its subschema, then validation succeeds against
+ * this keyword if the instance also successfully validates against this keyword’s subschema.<br/>
+ * <br/>
+ * <b>kind</b>
+ * <ul>
+ * <li>Applicator</li>
+ * </ul>
+ *
+ * source: https://www.learnjsonschema.com/2020-12/applicator/then/
+ * spec: https://json-schema.org/draft/2020-12/json-schema-core.html#section-10.2.2.2
+ */
+final class ThenKeyword implements Applicator {
+
+    static final String NAME = "then";
+    private final JsonSchema schema;
+
+    public ThenKeyword(final JsonSchema schema) {
+        this.schema = Objects.requireNonNull(schema);
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return Objects.equals(NAME, name);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return media.withValue(NAME, schema);
+    }
+
+    @Override
+    public boolean applyTo(final JsonValue instance) {
+        return schema.validator().isValid(instance);
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeywordTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeywordTest.java
new file mode 100644
index 0000000..f9a7db3
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedKeywordTest.java
@@ -0,0 +1,181 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.keyword.type;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.Matchers.is;
+
+import io.github.sebastiantoepfer.ddd.common.Media;
+import io.github.sebastiantoepfer.ddd.media.core.HashMapMedia;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.JsonValue;
+import java.util.Collection;
+import java.util.EnumSet;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+class LinkedKeywordTest {
+
+    @Test
+    void should_return_categories_from_both_keywords() {
+        assertThat(
+            new LinkedKeyword(new MockAnnotation(), LINKTYPE.VALID, new MockApplicator()).categories(),
+            containsInAnyOrder(Keyword.KeywordCategory.ANNOTATION, Keyword.KeywordCategory.APPLICATOR)
+        );
+    }
+
+    @Nested
+    class LinkTypeIsValid {
+
+        @Test
+        void should_valid_if_both_are_valid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(true), LINKTYPE.VALID, new MockApplicator(true))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(true)
+            );
+        }
+
+        @Test
+        void should_invalid_if_first_is_valid_and_second_is_invalid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(true), LINKTYPE.VALID, new MockApplicator(false))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(false)
+            );
+        }
+
+        @Test
+        void should_valid_if_first_is_invalid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(false), LINKTYPE.VALID, new MockApplicator(true))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(true)
+            );
+        }
+    }
+
+    @Nested
+    class LinkTypeIsInvalid {
+
+        @Test
+        void should_be_valid_if_first_is_valid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(true), LINKTYPE.INVALID, new MockApplicator(false))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(true)
+            );
+        }
+
+        @Test
+        void should_be_valid_if_first_is_invalid_and_second_is_valid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(false), LINKTYPE.INVALID, new MockApplicator(true))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(true)
+            );
+        }
+
+        @Test
+        void should_be_invalid_if_both_are_invalid() {
+            assertThat(
+                new LinkedKeyword(new MockApplicator(false), LINKTYPE.INVALID, new MockApplicator(false))
+                    .asApplicator()
+                    .applyTo(JsonValue.TRUE),
+                is(false)
+            );
+        }
+    }
+
+    @Test
+    void should_know_his_name() {
+        final Keyword keyword = new LinkedKeyword(new MockKeyword("if"), LINKTYPE.VALID, new MockKeyword("then"));
+
+        assertThat(keyword.hasName("if"), is(false));
+        assertThat(keyword.hasName("then"), is(true));
+    }
+
+    @Test
+    void should_use_second_to_print() {
+        assertThat(
+            new LinkedKeyword(new MockKeyword("if"), LINKTYPE.VALID, new MockKeyword("then")).printOn(
+                new HashMapMedia()
+            ),
+            is(new MockKeyword("then").printOn(new HashMapMedia()))
+        );
+    }
+
+    private static final class MockAnnotation implements Keyword {
+
+        @Override
+        public Collection<KeywordCategory> categories() {
+            return EnumSet.of(KeywordCategory.ANNOTATION, KeywordCategory.APPLICATOR);
+        }
+
+        @Override
+        public boolean hasName(String name) {
+            throw new UnsupportedOperationException("Not supported yet.");
+        }
+
+        @Override
+        public <T extends Media<T>> T printOn(T media) {
+            throw new UnsupportedOperationException("Not supported yet.");
+        }
+    }
+
+    private static final class MockApplicator implements Applicator {
+
+        private final boolean result;
+
+        public MockApplicator() {
+            this(true);
+        }
+
+        public MockApplicator(final boolean result) {
+            this.result = result;
+        }
+
+        @Override
+        public boolean applyTo(final JsonValue instance) {
+            return result;
+        }
+
+        @Override
+        public boolean hasName(String name) {
+            throw new UnsupportedOperationException("Not supported yet.");
+        }
+
+        @Override
+        public <T extends Media<T>> T printOn(T media) {
+            throw new UnsupportedOperationException("Not supported yet.");
+        }
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWithTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWithTest.java
new file mode 100644
index 0000000..c0f0925
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/LinkedWithTest.java
@@ -0,0 +1,68 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.keyword.type;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasItems;
+import static org.hamcrest.Matchers.not;
+
+import io.github.sebastiantoepfer.jsonschema.JsonSchemas;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.Json;
+import jakarta.json.JsonValue;
+import java.util.EnumSet;
+import org.junit.jupiter.api.Test;
+
+class LinkedWithTest {
+
+    @Test
+    void should_replace_keyword_if_previous_chain_link_not_available() {
+        assertThat(
+            new LinkedWith(
+                "if",
+                s -> new MockKeyword("if", EnumSet.of(Keyword.KeywordCategory.APPLICATOR)),
+                LINKTYPE.VALID
+            )
+                .findAffectedByKeywordIn(JsonSchemas.load(JsonValue.TRUE))
+                .apply(new MockKeyword("MOCK"))
+                .categories(),
+            not(hasItems(Keyword.KeywordCategory.ASSERTION, Keyword.KeywordCategory.APPLICATOR))
+        );
+    }
+
+    @Test
+    void should_chain_keyword_if_previous_chain_link_is_available() {
+        assertThat(
+            new LinkedWith(
+                "if",
+                s -> new MockKeyword("if", EnumSet.of(Keyword.KeywordCategory.APPLICATOR)),
+                LINKTYPE.VALID
+            )
+                .findAffectedByKeywordIn(JsonSchemas.load(Json.createObjectBuilder().add("if", JsonValue.TRUE).build()))
+                .apply(new ReplacingKeyword(new MockKeyword("MOCK"), EnumSet.of(Keyword.KeywordCategory.ASSERTION)))
+                .categories(),
+            hasItems(Keyword.KeywordCategory.APPLICATOR, Keyword.KeywordCategory.ANNOTATION)
+        );
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/MockKeyword.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/MockKeyword.java
index 35ba659..b1639ce 100644
--- a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/MockKeyword.java
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/keyword/type/MockKeyword.java
@@ -38,9 +38,15 @@
 final class MockKeyword implements Identifier, Assertion, Annotation, Applicator, ReservedLocation {
 
     private final String name;
+    private final Collection<KeywordCategory> categories;
 
     public MockKeyword(final String name) {
+        this(name, EnumSet.allOf(KeywordCategory.class));
+    }
+
+    public MockKeyword(final String name, final Collection<KeywordCategory> categories) {
         this.name = name;
+        this.categories = EnumSet.copyOf(categories);
     }
 
     @Override
@@ -65,7 +71,7 @@ public boolean applyTo(final JsonValue instance) {
 
     @Override
     public Collection<KeywordCategory> categories() {
-        return EnumSet.allOf(KeywordCategory.class);
+        return EnumSet.copyOf(categories);
     }
 
     @Override
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeywordTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeywordTest.java
new file mode 100644
index 0000000..4023f6c
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ElseKeywordTest.java
@@ -0,0 +1,82 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.is;
+
+import io.github.sebastiantoepfer.ddd.media.core.HashMapMedia;
+import io.github.sebastiantoepfer.jsonschema.JsonSchemas;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.Json;
+import jakarta.json.JsonValue;
+import org.hamcrest.Matcher;
+import org.junit.jupiter.api.Test;
+
+class ElseKeywordTest {
+
+    @Test
+    void should_know_his_name() {
+        final Keyword keyword = new ElseKeyword(JsonSchemas.load(JsonValue.TRUE));
+
+        assertThat(keyword.hasName("else"), is(true));
+        assertThat(keyword.hasName("test"), is(false));
+    }
+
+    @Test
+    void should_be_printable() {
+        assertThat(
+            new ElseKeyword(
+                JsonSchemas.load(
+                    Json.createObjectBuilder()
+                        .add(
+                            "properties",
+                            Json.createObjectBuilder().add("foo", Json.createObjectBuilder().add("type", "string"))
+                        )
+                        .add("required", Json.createArrayBuilder().add("foo"))
+                        .build()
+                )
+            ).printOn(new HashMapMedia()),
+            (Matcher) hasEntry(is("else"), hasKey("properties"))
+        );
+    }
+
+    @Test
+    void should_be_valid_if_instance_successful_validates_against_schema() {
+        assertThat(
+            new ElseKeyword(JsonSchemas.load(JsonValue.TRUE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_invalid_if_instance_not_successful_validates_against_schema() {
+        assertThat(
+            new ElseKeyword(JsonSchemas.load(JsonValue.FALSE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(false)
+        );
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeywordTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeywordTest.java
new file mode 100644
index 0000000..f9d8500
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/IfKeywordTest.java
@@ -0,0 +1,82 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.is;
+
+import io.github.sebastiantoepfer.ddd.media.core.HashMapMedia;
+import io.github.sebastiantoepfer.jsonschema.JsonSchemas;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.Json;
+import jakarta.json.JsonValue;
+import org.hamcrest.Matcher;
+import org.junit.jupiter.api.Test;
+
+class IfKeywordTest {
+
+    @Test
+    void should_know_his_name() {
+        final Keyword keyword = new IfKeyword(JsonSchemas.load(JsonValue.TRUE));
+
+        assertThat(keyword.hasName("if"), is(true));
+        assertThat(keyword.hasName("test"), is(false));
+    }
+
+    @Test
+    void should_be_printable() {
+        assertThat(
+            new IfKeyword(
+                JsonSchemas.load(
+                    Json.createObjectBuilder()
+                        .add(
+                            "properties",
+                            Json.createObjectBuilder().add("foo", Json.createObjectBuilder().add("type", "string"))
+                        )
+                        .add("required", Json.createArrayBuilder().add("foo"))
+                        .build()
+                )
+            ).printOn(new HashMapMedia()),
+            (Matcher) hasEntry(is("if"), hasKey("properties"))
+        );
+    }
+
+    @Test
+    void should_be_valid_if_instance_successful_validates_against_schema() {
+        assertThat(
+            new IfKeyword(JsonSchemas.load(JsonValue.TRUE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_invalid_if_instance_not_successful_validates_against_schema() {
+        assertThat(
+            new IfKeyword(JsonSchemas.load(JsonValue.FALSE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(false)
+        );
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeywordTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeywordTest.java
new file mode 100644
index 0000000..17d0e28
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ThenKeywordTest.java
@@ -0,0 +1,82 @@
+/*
+ * The MIT License
+ *
+ * Copyright 2024 sebastian.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package io.github.sebastiantoepfer.jsonschema.core.vocab.applicator;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.hasEntry;
+import static org.hamcrest.Matchers.hasKey;
+import static org.hamcrest.Matchers.is;
+
+import io.github.sebastiantoepfer.ddd.media.core.HashMapMedia;
+import io.github.sebastiantoepfer.jsonschema.JsonSchemas;
+import io.github.sebastiantoepfer.jsonschema.keyword.Keyword;
+import jakarta.json.Json;
+import jakarta.json.JsonValue;
+import org.hamcrest.Matcher;
+import org.junit.jupiter.api.Test;
+
+class ThenKeywordTest {
+
+    @Test
+    void should_know_his_name() {
+        final Keyword keyword = new ThenKeyword(JsonSchemas.load(JsonValue.TRUE));
+
+        assertThat(keyword.hasName("then"), is(true));
+        assertThat(keyword.hasName("test"), is(false));
+    }
+
+    @Test
+    void should_be_printable() {
+        assertThat(
+            new ThenKeyword(
+                JsonSchemas.load(
+                    Json.createObjectBuilder()
+                        .add(
+                            "properties",
+                            Json.createObjectBuilder().add("foo", Json.createObjectBuilder().add("type", "string"))
+                        )
+                        .add("required", Json.createArrayBuilder().add("foo"))
+                        .build()
+                )
+            ).printOn(new HashMapMedia()),
+            (Matcher) hasEntry(is("then"), hasKey("properties"))
+        );
+    }
+
+    @Test
+    void should_be_valid_if_instance_successful_validates_against_schema() {
+        assertThat(
+            new ThenKeyword(JsonSchemas.load(JsonValue.TRUE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_invalid_if_instance_not_successful_validates_against_schema() {
+        assertThat(
+            new ThenKeyword(JsonSchemas.load(JsonValue.FALSE)).asApplicator().applyTo(JsonValue.EMPTY_JSON_OBJECT),
+            is(false)
+        );
+    }
+}