diff --git a/core/pom.xml b/core/pom.xml
index 5fce5ef..590b5e6 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -157,6 +157,7 @@
                     <include>**/tests/draft2020-12/patternProperties.json</include>
                     <include>**/tests/draft2020-12/prefixItems.json</include>
                     <include>**/tests/draft2020-12/properties.json</include>
+                    <include>**/tests/draft2020-12/propertyNames.json</include>
                     <!--
                     needs allOf, $anchor and dynamicAnchor and some other stuff :(
                     <include>**/tests/draft2020-12/ref.json</include>
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/Keywords.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/Keywords.java
index df24336..d4c826f 100644
--- a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/Keywords.java
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/Keywords.java
@@ -59,7 +59,7 @@ final class Keywords {
             .collect(toMap(Vocabulary::id, Function.identity()));
 
         DEFAULT_VOCABS = List.of(
-            new ApplicatorVocabulary(),
+            new ApplicatorVocabulary(JsonProvider.provider()),
             new ValidationVocabulary(JsonProvider.provider()),
             new MetaDataVocabulary(),
             new FormatAnnotationVocabulary(),
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/OfficialVocabularies.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/OfficialVocabularies.java
index 78d5376..d3c8118 100644
--- a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/OfficialVocabularies.java
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/OfficialVocabularies.java
@@ -46,7 +46,7 @@ public final class OfficialVocabularies implements LazyVocabularies {
     static {
         OFFICEAL_VOCABS = List.of(
             new CoreVocabulary(JSONP),
-            new ApplicatorVocabulary(),
+            new ApplicatorVocabulary(JSONP),
             new ValidationVocabulary(JSONP),
             new MetaDataVocabulary(),
             new FormatAnnotationVocabulary(),
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 75384f9..9d542a8 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
@@ -36,6 +36,7 @@
 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.List;
 import java.util.Optional;
@@ -51,7 +52,7 @@ public final class ApplicatorVocabulary implements Vocabulary {
 
     private final Vocabulary vocab;
 
-    public ApplicatorVocabulary() {
+    public ApplicatorVocabulary(final JsonProvider provider) {
         this.vocab = new ListVocabulary(
             URI.create("https://json-schema.org/draft/2020-12/vocab/applicator"),
             new SchemaArrayKeywordType(AllOfKeyword.NAME, AllOfKeyword::new),
@@ -74,6 +75,7 @@ public ApplicatorVocabulary() {
             ),
             new NamedJsonSchemaKeywordType(PatternPropertiesKeyword.NAME, PatternPropertiesKeyword::new),
             new NamedJsonSchemaKeywordType(DependentSchemasKeyword.NAME, DependentSchemasKeyword::new),
+            new SubSchemaKeywordType(PropertyNames.NAME, s -> new PropertyNames(provider, s)),
             //this example shows my missunderstanding from affects, affectedBy and keywordtypes :(
             new AffectedByKeywordType(
                 ItemsKeyword.NAME,
diff --git a/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNames.java b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNames.java
new file mode 100644
index 0000000..8ced4ee
--- /dev/null
+++ b/core/src/main/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNames.java
@@ -0,0 +1,79 @@
+/*
+ * 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.InstanceType;
+import io.github.sebastiantoepfer.jsonschema.JsonSchema;
+import io.github.sebastiantoepfer.jsonschema.Validator;
+import io.github.sebastiantoepfer.jsonschema.keyword.Applicator;
+import jakarta.json.JsonObject;
+import jakarta.json.JsonValue;
+import jakarta.json.spi.JsonProvider;
+import java.util.Objects;
+
+/**
+ * <b>propertyNames</b> : <i>Schema</i><br/>
+ * Validation succeeds if the schema validates against every property name in the instance.<br/>
+ * <br/>
+ * <b>Kind</b><br/>
+ * <ul>
+ * <li>Applicator</li>
+ * </li>
+ * </ul>
+ *
+ * source: https://www.learnjsonschema.com/2020-12/applicator/propertynames/
+ * spec: https://json-schema.org/draft/2020-12/json-schema-core.html#section-10.3.2.4
+ */
+final class PropertyNames implements Applicator {
+
+    static final String NAME = "propertyNames";
+    private final JsonProvider provider;
+    private final JsonSchema names;
+
+    public PropertyNames(final JsonProvider provider, final JsonSchema names) {
+        this.provider = Objects.requireNonNull(provider);
+        this.names = Objects.requireNonNull(names);
+    }
+
+    @Override
+    public <T extends Media<T>> T printOn(final T media) {
+        return media.withValue(NAME, names);
+    }
+
+    @Override
+    public boolean hasName(final String name) {
+        return Objects.equals(NAME, name);
+    }
+
+    @Override
+    public boolean applyTo(final JsonValue instance) {
+        return !InstanceType.OBJECT.isInstance(instance) || allProperyNamesMatchesSchema(instance.asJsonObject());
+    }
+
+    private boolean allProperyNamesMatchesSchema(final JsonObject obj) {
+        final Validator validator = names.validator();
+        return obj.keySet().stream().map(provider::createValue).allMatch(validator::isValid);
+    }
+}
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabularyTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabularyTest.java
index 8ad288f..daa9b23 100644
--- a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabularyTest.java
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/ApplicatorVocabularyTest.java
@@ -27,6 +27,7 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 
 import io.github.sebastiantoepfer.jsonschema.keyword.KeywordType;
+import jakarta.json.spi.JsonProvider;
 import org.junit.jupiter.api.Test;
 
 class ApplicatorVocabularyTest {
@@ -34,7 +35,7 @@ class ApplicatorVocabularyTest {
     @Test
     void should_find_items_keyword() {
         assertThat(
-            new ApplicatorVocabulary().findKeywordTypeByName("items").map(KeywordType::name),
+            new ApplicatorVocabulary(JsonProvider.provider()).findKeywordTypeByName("items").map(KeywordType::name),
             isPresentAndIs("items")
         );
     }
diff --git a/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNamesTest.java b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNamesTest.java
new file mode 100644
index 0000000..e0e8a42
--- /dev/null
+++ b/core/src/test/java/io/github/sebastiantoepfer/jsonschema/core/vocab/applicator/PropertyNamesTest.java
@@ -0,0 +1,93 @@
+/*
+ * 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.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 jakarta.json.spi.JsonProvider;
+import org.hamcrest.Matcher;
+import org.hamcrest.Matchers;
+import org.junit.jupiter.api.Test;
+
+class PropertyNamesTest {
+
+    @Test
+    void should_be_know_his_name() {
+        final Keyword keyword = new PropertyNames(JsonProvider.provider(), JsonSchemas.load(JsonValue.TRUE));
+
+        assertThat(keyword.hasName("propertyNames"), is(true));
+        assertThat(keyword.hasName("test"), is(false));
+    }
+
+    @Test
+    void should_be_printable() {
+        assertThat(
+            new PropertyNames(JsonProvider.provider(), JsonSchemas.load(JsonValue.TRUE)).printOn(new HashMapMedia()),
+            hasEntry(is("propertyNames"), (Matcher) Matchers.anEmptyMap())
+        );
+    }
+
+    @Test
+    void should_be_valid_for_non_objects() {
+        assertThat(
+            new PropertyNames(JsonProvider.provider(), JsonSchemas.load(JsonValue.TRUE))
+                .asApplicator()
+                .applyTo(JsonValue.EMPTY_JSON_ARRAY),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_valid_if_schema_applies_to_all_propertyNames() {
+        assertThat(
+            new PropertyNames(
+                JsonProvider.provider(),
+                JsonSchemas.load(Json.createObjectBuilder().add("maxLength", 3).build())
+            )
+                .asApplicator()
+                .applyTo(Json.createObjectBuilder().add("foo", "foo").add("bar", 33).build()),
+            is(true)
+        );
+    }
+
+    @Test
+    void should_be_invalid_if_schema_does_not_applies_to_any_propertyName() {
+        assertThat(
+            new PropertyNames(
+                JsonProvider.provider(),
+                JsonSchemas.load(Json.createObjectBuilder().add("maxLength", 3).build())
+            )
+                .asApplicator()
+                .applyTo(Json.createObjectBuilder().add("name", "John Doe").add("age", 21).build()),
+            is(false)
+        );
+    }
+}