diff --git a/pom.xml b/pom.xml
index b7a5ba5..1dca9bc 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>de.arraying</groupId>
     <artifactId>Kotys</artifactId>
-    <version>0.5.2</version>
+    <version>0.6.0</version>
     <build>
         <plugins>
             <plugin>
diff --git a/src/main/java/de/arraying/kotys/JSON.java b/src/main/java/de/arraying/kotys/JSON.java
index 21da5b3..ce7794a 100644
--- a/src/main/java/de/arraying/kotys/JSON.java
+++ b/src/main/java/de/arraying/kotys/JSON.java
@@ -4,6 +4,7 @@
 import java.io.IOException;
 import java.io.StringReader;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * Copyright 2017 Arraying
@@ -23,10 +24,10 @@
 @SuppressWarnings({"WeakerAccess", "unused", "UnusedReturnValue"})
 public class JSON {
 
-    private final Map<String, Object> rawContent = new LinkedHashMap<>();
     private static final JSONUtil util = new JSONUtil();
-
-    private JSONMarshalFormat format = null;
+    private final Object writeLock = new Object();
+    private Map<String, Object> rawContent = new HashMap<>();
+    private JSONFormatter formatter = new JSONFormatter.DefaultImplementation();
 
     /**
      * Creates an empty JSON object.
@@ -118,6 +119,39 @@ public JSON(File file)
         this(util.getFileContent(file, true));
     }
 
+    /**
+     * Specifies the map type to use for internal storage.
+     * This is so that when marshalling some specific ordering is retained.
+     * This map will get cleared.
+     * Note that a {@link java.util.concurrent.ConcurrentHashMap} is not allowed.
+     * @param map The map.
+     */
+    public void use(Map<String, Object> map) {
+        if(map == null) {
+            throw new IllegalArgumentException("Provided map is null");
+        }
+        if(map instanceof ConcurrentHashMap) {
+            throw new IllegalArgumentException("ConcurrentHashMap not allowed");
+        }
+        Map<String, Object> cache = new HashMap<>(rawContent);
+        map.clear();
+        synchronized(writeLock) {
+            rawContent = map;
+            rawContent.putAll(cache);
+        }
+    }
+
+    /**
+     * Specifies the formatter to use when marshalling to a string.
+     * @param formatter A formatter instance.
+     */
+    public void use(JSONFormatter formatter) {
+        if(formatter == null) {
+            throw new IllegalArgumentException("Formatter is null");
+        }
+        this.formatter = formatter;
+    }
+
     /**
      * Adds an entry to the current JSON object.
      * This entry can either be a raw JSON data type, or a custom object.
@@ -132,7 +166,9 @@ public JSON put(String key, Object entry)
         if(key == null) {
             throw new IllegalArgumentException("Provided key is null");
         }
-        rawContent.put(key, util.getFinalValue(entry));
+        synchronized(writeLock) {
+            rawContent.put(key, util.getFinalValue(entry));
+        }
         return this;
     }
 
@@ -147,7 +183,9 @@ public JSON remove(String key)
         if(key == null) {
             throw new IllegalArgumentException("Provided key is null");
         }
-        rawContent.remove(key);
+        synchronized(writeLock) {
+            rawContent.remove(key);
+        }
         return this;
     }
 
@@ -286,27 +324,19 @@ public final int length() {
      * @return A string representation of the JSON object.
      */
     public final String marshal() {
-        JSONFormatter formatter = new JSONFormatter()
-                .startObject();
+        formatter.startObject();
         Iterator<Map.Entry<String, Object>> iterator = rawContent.entrySet().iterator();
         while(iterator.hasNext()) {
             Map.Entry<String, Object> entry = iterator.next();
             formatter.objectKey(entry.getKey());
             Object valueRaw = entry.getValue();
-            if(valueRaw instanceof JSON) {
-                formatter.object(((JSON) valueRaw).marshal());
-            } else if(valueRaw instanceof JSONArray) {
-                formatter.array(((JSONArray) valueRaw).marshal());
-            } else {
-                formatter.value(valueRaw);
-            }
+            util.format(formatter, valueRaw);
             if(iterator.hasNext()) {
                 formatter.comma();
             }
         }
         formatter.endObject();
-
-        return format != null ? format.format(formatter.result()) : formatter.result();
+        return formatter.result();
     }
 
     /**
@@ -336,16 +366,6 @@ public final <T> T marshal(Class<T> clazz, String... ignoredKeys)
         return new JSONORM<>(clazz).mapTo(this, ignoredKeys);
     }
 
-    /**
-     * Set formatting to be applied for String marshal()
-     * @param format - Format to be applied to String marshal()
-     */
-
-    public JSON setFormat(JSONMarshalFormat format) {
-        this.format = format;
-        return this;
-    }
-
     /**
      * Converts the JSON object to a string.
      * This method invokes the {@link #marshal()} method.
diff --git a/src/main/java/de/arraying/kotys/JSONArray.java b/src/main/java/de/arraying/kotys/JSONArray.java
index e8c3ea7..6bd0042 100644
--- a/src/main/java/de/arraying/kotys/JSONArray.java
+++ b/src/main/java/de/arraying/kotys/JSONArray.java
@@ -24,8 +24,10 @@
 @SuppressWarnings({"WeakerAccess", "unused", "UnusedReturnValue"})
 public class JSONArray implements Iterator<Object> {
 
-    private final List<Object> rawContent = new ArrayList<>();
     private static final JSONUtil util = new JSONUtil();
+    private final Object writeLock = new Object();
+    private final List<Object> rawContent = new ArrayList<>();
+    private JSONFormatter formatter = new JSONFormatter.DefaultImplementation();
 
     /**
      * Creates an empty JSON array.
@@ -88,6 +90,16 @@ public JSONArray(File file)
             throws IOException, IllegalStateException {
         this(util.getFileContent(file, false));
     }
+    /**
+     * Specifies the formatter to use when marshalling to a string.
+     * @param formatter A formatter instance.
+     */
+    public void use(JSONFormatter formatter) {
+        if(formatter == null) {
+            throw new IllegalArgumentException("Formatter is null");
+        }
+        this.formatter = formatter;
+    }
 
     /**
      * Appends a value to the array.
@@ -98,8 +110,10 @@ public JSONArray(File file)
      */
     public JSONArray append(Object... values)
             throws IllegalArgumentException {
-        for(Object object : values) {
-            rawContent.add(util.getFinalValue(object));
+        synchronized(writeLock) {
+            for(Object object : values) {
+                rawContent.add(util.getFinalValue(object));
+            }
         }
         return this;
     }
@@ -110,7 +124,9 @@ public JSONArray append(Object... values)
      * @return The object that was removed from the Array.
      */
     public Object delete(int index) {
-        return rawContent.remove(index);
+        synchronized(writeLock) {
+            return rawContent.remove(index);
+        }
     }
 
     /**
@@ -243,17 +259,10 @@ public final Object[] toArray() {
      * @return A string representation of the JSON array.
      */
     public final String marshal() {
-        JSONFormatter formatter = new JSONFormatter()
-                .startArray();
+        formatter.startArray();
         for(int i = 0; i < length(); i++) {
                 Object valueRaw = rawContent.get(i);
-                if(valueRaw instanceof JSON) {
-                    formatter.object(((JSON) valueRaw).marshal());
-                } else if(valueRaw instanceof JSONArray) {
-                    formatter.array(((JSONArray) valueRaw).marshal());
-                } else {
-                    formatter.value(valueRaw);
-                }
+                util.format(formatter, valueRaw);
             if(i + 1 < length()) {
                 formatter.comma();
             }
diff --git a/src/main/java/de/arraying/kotys/JSONDefaultMarshalFormat.java b/src/main/java/de/arraying/kotys/JSONDefaultMarshalFormat.java
deleted file mode 100644
index 4aa6aa6..0000000
--- a/src/main/java/de/arraying/kotys/JSONDefaultMarshalFormat.java
+++ /dev/null
@@ -1,85 +0,0 @@
-package de.arraying.kotys;
-
-/**
- * Copyright 2019 ipr0james
- * <p>
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * <p>
- * http://www.apache.org/licenses/LICENSE-2.0
- * <p>
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-public class JSONDefaultMarshalFormat implements JSONMarshalFormat {
-
-    @Override
-    public String format(String json) {
-        StringBuilder builder = new StringBuilder();
-        int indentLevel = 0;
-        boolean inQuote = false;
-
-        for(char type : json.toCharArray()) {
-            switch(type) {
-                case '"':
-                    // switch the quoting status
-                    inQuote = !inQuote;
-                    builder.append(type);
-                    break;
-                case ' ':
-                    // For space: ignore the space if it is not being quoted.
-                    if(inQuote) {
-                        builder.append(type);
-                    }
-                    break;
-                case '{':
-                case '[':
-                    // Starting a new block: increase the indent level
-                    builder.append(type);
-                    if(!inQuote) {
-                        indentLevel++;
-                        appendIndentedNewLine(indentLevel, builder);
-                    }
-                    break;
-                case '}':
-                case ']':
-                    // Ending a new block; decrese the indent level
-                    if(!inQuote) {
-                        indentLevel--;
-                        appendIndentedNewLine(indentLevel, builder);
-                    }
-                    builder.append(type);
-                    break;
-                case ',':
-                    // Ending a json item; create a new line after
-                    builder.append(type);
-                    if(!inQuote) {
-                        appendIndentedNewLine(indentLevel, builder);
-                    }
-                    break;
-                case ':':
-                    if(!inQuote) {
-                        builder.append(": ");
-                    }
-                    break;
-                default:
-                    builder.append(type);
-            }
-        }
-        return builder.toString();
-    }
-
-    /**
-     * Print a new line with indention at the beginning of the new line.
-     */
-    private void appendIndentedNewLine(int indentLevel, StringBuilder builder) {
-        builder.append("\n");
-        for(int i = 0; i < indentLevel; i++) {
-            builder.append("  ");
-        }
-    }
-}
diff --git a/src/main/java/de/arraying/kotys/JSONFormatter.java b/src/main/java/de/arraying/kotys/JSONFormatter.java
index c9d7056..bfc10ea 100644
--- a/src/main/java/de/arraying/kotys/JSONFormatter.java
+++ b/src/main/java/de/arraying/kotys/JSONFormatter.java
@@ -16,110 +16,186 @@
  * limitations under the License.
  */
 @SuppressWarnings("UnusedReturnValue")
-final class JSONFormatter {
-
-    private final StringBuilder builder = new StringBuilder();
+public interface JSONFormatter {
 
     /**
      * Starts a new JSON object.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter startObject() {
-        builder.append("{");
-        return this;
-    }
+    JSONFormatter startObject();
 
     /**
      * Ends the JSON object.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter endObject() {
-        builder.append("}");
-        return this;
-    }
+    JSONFormatter endObject();
 
     /**
      * Starts a new JSON array.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter startArray() {
-        builder.append("[");
-        return this;
-    }
+    JSONFormatter startArray();
 
     /**
      * Ends the JSON array.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter endArray() {
-        builder.append("]");
-        return this;
-    }
+    JSONFormatter endArray();
 
     /**
      * Appends a comma.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter comma() {
-        builder.append(",");
-        return this;
-    }
+    JSONFormatter comma();
 
     /**
      * Appends an object.
      * @param object The object.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter object(String object) {
-        builder.append(object);
-        return this;
-    }
+    JSONFormatter object(String object);
 
     /**
      * Appends an array.
      * @param array The array.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter array(String array) {
-        builder.append(array);
-        return this;
-    }
+    JSONFormatter array(String array);
 
     /**
      * Appends an object key.
      * @param key The key of the object.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter objectKey(String key) {
-        builder.append("\"")
-                .append(key)
-                .append("\"")
-                .append(":");
-        return this;
-    }
+    JSONFormatter objectKey(String key);
 
     /**
      * Appends the value.
      * @param value The value of the object.
      * @return The formatter for chaining purposes.
      */
-    JSONFormatter value(Object value) {
-        if(value instanceof String) {
-            builder.append("\"")
-                    .append(value)
-                    .append("\"");
-        } else {
-            builder.append(value);
-        }
-        return this;
-    }
+    JSONFormatter value(Object value);
 
     /**
      * Gets the result of the formatting.
      * @return The resultant string.
      */
-    String result() {
-        return builder.toString();
+    String result();
+
+    /**
+     * Default implementation, minimal JSON formatter.
+     */
+    final class DefaultImplementation implements JSONFormatter {
+
+        private final StringBuilder builder = new StringBuilder();
+
+        /**
+         * Adds an opening brace.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter startObject() {
+            builder.append("{");
+            return this;
+        }
+
+        /**
+         * Adds a closing brace.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter endObject() {
+            builder.append("}");
+            return this;
+        }
+
+        /**
+         * Adds an opening bracket.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter startArray() {
+            builder.append("[");
+            return this;
+        }
+
+        /**
+         * Adds a closing bracket.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter endArray() {
+            builder.append("]");
+            return this;
+        }
+
+        /**
+         * Adds a comma.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter comma() {
+            builder.append(",");
+            return this;
+        }
+
+        /**
+         * Adds a JSON object.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter object(String object) {
+            builder.append(object);
+            return this;
+        }
+
+        /**
+         * Adds a JSON array.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter array(String array) {
+            builder.append(array);
+            return this;
+        }
+
+        /**
+         * Adds an object key, a string enclosed in quotation marks followed by a colon.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter objectKey(String key) {
+            builder.append("\"")
+                    .append(key)
+                    .append("\"")
+                    .append(":");
+            return this;
+        }
+
+        /**
+         * Adds a numerical of textual value.
+         * @return This.
+         */
+        @Override
+        public JSONFormatter value(Object value) {
+            if(value instanceof String) {
+                builder.append("\"")
+                        .append(value)
+                        .append("\"");
+            } else {
+                builder.append(value);
+            }
+            return this;
+        }
+
+        /**
+         * @return The resultant string.
+         */
+        @Override
+        public String result() {
+            return builder.toString();
+        }
+
     }
 
 }
diff --git a/src/main/java/de/arraying/kotys/JSONMarshalFormat.java b/src/main/java/de/arraying/kotys/JSONMarshalFormat.java
deleted file mode 100644
index 5cda93e..0000000
--- a/src/main/java/de/arraying/kotys/JSONMarshalFormat.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package de.arraying.kotys;
-
-/**
- * Copyright 2019 ipr0james
- * <p>
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * <p>
- * http://www.apache.org/licenses/LICENSE-2.0
- * <p>
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-public interface JSONMarshalFormat {
-
-    String format(String json);
-}
diff --git a/src/main/java/de/arraying/kotys/JSONUtil.java b/src/main/java/de/arraying/kotys/JSONUtil.java
index e1b7ec8..ae7deb3 100644
--- a/src/main/java/de/arraying/kotys/JSONUtil.java
+++ b/src/main/java/de/arraying/kotys/JSONUtil.java
@@ -62,6 +62,22 @@ String getFileContent(File file, boolean object)
         return new String(Files.readAllBytes(file.toPath()));
     }
 
+    /**
+     * Applies a raw JSON object to the formatter.
+     * This method exists such that there's no duplicate method.
+     * @param formatter The formatter instance.
+     * @param valueRaw The raw value.
+     */
+    void format(JSONFormatter formatter, Object valueRaw) {
+        if(valueRaw instanceof JSON) {
+            formatter.object(((JSON) valueRaw).marshal());
+        } else if(valueRaw instanceof JSONArray) {
+            formatter.array(((JSONArray) valueRaw).marshal());
+        } else {
+            formatter.value(valueRaw);
+        }
+    }
+
     /**
      * Checks if the specified object is a valid JSON data type.
      * This presumes that all arrays have already been parsed.