diff --git a/assembly/encoder.ts b/assembly/encoder.ts
index 467e29f..8028f6d 100644
--- a/assembly/encoder.ts
+++ b/assembly/encoder.ts
@@ -1,131 +1,119 @@
-const START_SIZE = 32;
-// Growth should be aggressive as we don't free old buffer
-const GROWTH_MULT = 2;
-
 declare function logStr(str: string): void;
 declare function logF64(val: f64): void;
 
-export class BSONEncoder {
-    offsets: Array<i32> = new Array<i32>();
-    buffer: Uint8Array = new Uint8Array(START_SIZE)
-    writeIndex: i32 = 4  // Make place for total size 
+export class JSONEncoder {
+    private isFirstKey: boolean = true
+    private inObject: Array<boolean> = [false]
+    private result: string = ""
 
     serialize(): Uint8Array {
-        this.writeByte(0);
-        this.int32(this.writeIndex, 0);
-        return this.buffer.subarray(0, this.writeIndex);
+        // TODO: Write directly to UTF8 bytes
+        let utf8ptr = this.result.toUTF8();
+        let buffer = new Uint8Array(this.result.lengthUTF8);
+        for (let i = 0; i <  buffer.length; i++) {
+            buffer[i] = load<u8>(utf8ptr + i);
+        }
+        return buffer.subarray(0, buffer.length - 1);
     }
 
     setString(name: string, value: string): void {
-        this.writeByte(0x02);           // BSON type: String
-        this.cstring(name);
-        let startOffset = this.writeIndex;
-        this.writeIndex += 4;
-        this.cstring(value);
-        this.int32(this.writeIndex - startOffset - 4, startOffset);
+        this.writeKey(name);
+        this.writeString(value);
     }
 
     setBoolean(name: string, value: bool): void {
-        this.writeByte(0x08);           // BSON type: Boolean
-        this.cstring(name);
-        this.writeByte(value ? 1 : 0);
+        this.writeKey(name);
+        this.writeBoolean(value);
     }
 
     setNull(name: string): void {
-        this.writeByte(0x0A);             // BSON type: Null
-        this.cstring(name);
+        this.writeKey(name);
+        this.write("null");
     }
 
     setInteger(name: string, value: i32): void {
-        this.writeByte(0x10);       // BSON type: int32
-        this.cstring(name);
-        this.int32(value);
+        this.writeKey(name);
+        this.writeInteger(value);
     }
 
-    setUint8Array(name: string, value: Uint8Array): void {
-        this.writeByte(0x05);           // BSON type: Binary data
-        this.cstring(name);
-        this.int32(value.length);
-        this.writeByte(0);              // use generic binary subtype 0
-        for (let i = 0; i < value.length; i++) {
-            this.writeByte(value[i]);
-        }
-    }
-
-    pushArray(name: string): void {
-        this.writeByte(0x04);           // BSON type: Array
-        this.cstring(name);
-        this.offsets.push(this.writeIndex);
-        this.writeIndex += 4;
+    pushArray(name: string): bool {
+        this.writeKey(name);
+        this.write("[");
+        this.isFirstKey = true
+        this.inObject.push(false);
+        return true;
     }
 
     popArray(): void {
-        this.writeByte(0);
-        let startOffset = this.offsets.pop();
-        this.int32(this.writeIndex - startOffset, startOffset);
+        this.write("]");
     }
 
-    pushObject(name: string): void {
-        this.writeByte(0x03);           // BSON type: Document
-        this.cstring(name);
-        this.offsets.push(this.writeIndex);
-        this.writeIndex += 4;
+    pushObject(name: string): bool {
+        this.writeKey(name);
+        this.write("{");
+        this.isFirstKey = true
+        this.inObject.push(true);
+        return true;
     }
 
     popObject(): void {
-        this.writeByte(0);
-        let startOffset = this.offsets.pop();
-        this.int32(this.writeIndex - startOffset, startOffset);
+        this.write("}");
     }
 
-    private cstring(str: string): void {
-        // TODO: Handle newlines properly
-        // str = str.replace(/\r\n/g, '\n');
-        // TODO: Maybe use AssemblyScript std Unicode conversion?
-        for (let i = 0, len = str.length; i < len; i++) {
-            let c = str.charCodeAt(i);
-            if (c < 128) {
-                this.writeByte(c);
-            } else if (c < 2048) {
-                this.writeByte((c >>> 6) | 192);
-                this.writeByte((c & 63) | 128);
-            } else {
-                this.writeByte((c >>> 12) | 224);
-                this.writeByte(((c >>> 6) & 63) | 128);
-                this.writeByte((c & 63) | 128);
+    private writeKey(str: string): void {
+        if (!this.isFirstKey ) {
+            this.write(",");
+        } else {
+            this.isFirstKey = false;
+        }
+        if (str != null) {
+            this.writeString(str);
+            this.write(":");
+        }
+    }
+
+    private writeString(str: string): void {
+        this.write('"');
+        let savedIndex = 0;
+        for (let i = 0; i < str.length; i++) {
+            let char = str.charCodeAt(i);
+            let needsEscaping = char < 0x20 || char == '"'.charCodeAt(0) || char == '\\'.charCodeAt(0);
+            if (needsEscaping) {
+                this.write(str.substring(savedIndex, i));
+                savedIndex = i + 1;
+                if (char == '"'.charCodeAt(0)) {
+                    this.write('\\"');
+                } else if (char == "\\".charCodeAt(0)) {
+                    this.write("\\\\");
+                } else if (char == "\b".charCodeAt(0)) {
+                    this.write("\\b");
+                } else if (char == "\n".charCodeAt(0)) {
+                    this.write("\\n");
+                } else if (char == "\r".charCodeAt(0)) {
+                    this.write("\\r");
+                } else if (char == "\t".charCodeAt(0)) {
+                    this.write("\\t");
+                } else {
+                    // TODO: Implement encoding for other contol characters
+                    assert(false, "Unsupported control chracter");
+                }
             }
         }
-        this.writeByte(0);
+        this.write(str.substring(savedIndex, str.length));
+        this.write('"');
     }
 
-    private int32(num: i32, offset: i32 = -1): void {
-        if (offset == -1) {
-            this.growIfNeeded(4);
-            offset = this.writeIndex;
-            this.writeIndex += 4;
-        }
-        this.buffer[offset] = (num) & 0xff;
-        this.buffer[offset + 1] = (num >>> 8) & 0xff;
-        this.buffer[offset + 2] = (num >>> 16) & 0xff;
-        this.buffer[offset + 3] = (num >>> 24) & 0xff;
+    private writeBoolean(value: bool): void {
+        this.write(value ? "true" : "false");
     }
 
-    private writeByte(b: u32): void {
-        this.growIfNeeded(1);
-        this.buffer[this.writeIndex++] = b;
+    private writeInteger(value: i32): void {
+        // TODO: More efficient encoding
+        let arr: Array<i32> = [value];
+        this.write(arr.toString());
     }
 
-    private growIfNeeded(numBytes: i32): void {
-        if (this.buffer.length >= this.writeIndex + numBytes) {
-            return;
-        }
-
-        let oldBuffer = this.buffer;
-        this.buffer = new Uint8Array(this.buffer.length * GROWTH_MULT);
-        for (let i = 0; i < oldBuffer.length; i++) {
-            this.buffer[i] = oldBuffer[i];
-        }
+    private write(str: string): void {
+        this.result += str;
     }
-}
-
-
+}
\ No newline at end of file
diff --git a/tests/assembly/roundtrip.spec.as.ts b/tests/assembly/roundtrip.spec.as.ts
index 5a0d221..a7e5f45 100644
--- a/tests/assembly/roundtrip.spec.as.ts
+++ b/tests/assembly/roundtrip.spec.as.ts
@@ -1,126 +1,19 @@
 import "allocator/arena";
 
-import { JSONDecoder, JSONHandler } from "../../assembly/decoder";
+import { JSONDecoder } from "../../assembly/decoder";
+import { JSONEncoder } from "../../assembly/encoder";
 
 declare function logStr(str: string): void;
 declare function logF64(val: f64): void;
 
-class JSONTestHandler extends JSONHandler {
-    isFirstKey: boolean = true
-    inObject: Array<boolean> = [false]
-    result: string = ""
-
-    setString(name: string, value: string): void {
-        this.writeKey(name);
-        this.writeString(value);
-    }
-
-    setBoolean(name: string, value: bool): void {
-        this.writeKey(name);
-        this.writeBoolean(value);
-    }
-
-    setNull(name: string): void {
-        this.writeKey(name);
-        this.write("null");
-    }
-
-    setInteger(name: string, value: i32): void {
-        this.writeKey(name);
-        this.writeInteger(value);
-    }
-
-    pushArray(name: string): bool {
-        this.writeKey(name);
-        this.write("[");
-        this.isFirstKey = true
-        this.inObject.push(false);
-        return true;
-    }
-
-    popArray(): void {
-        this.write("]");
-    }
-
-    pushObject(name: string): bool {
-        this.writeKey(name);
-        this.write("{");
-        this.isFirstKey = true
-        this.inObject.push(true);
-        return true;
-    }
-
-    popObject(): void {
-        this.write("}");
-    }
-
-    private writeKey(str: string): void {
-        if (!this.isFirstKey ) {
-            this.write(",");
-        } else {
-            this.isFirstKey = false;
-        }
-        if (str != null) {
-            this.writeString(str);
-            this.write(":");
-        }
-    }
-
-    private writeString(str: string): void {
-        this.write('"');
-        let savedIndex = 0;
-        for (let i = 0; i < str.length; i++) {
-            let char = str.charCodeAt(i);
-            let needsEscaping = char < 0x20 || char == '"'.charCodeAt(0) || char == '\\'.charCodeAt(0);
-            if (needsEscaping) {
-                this.write(str.substring(savedIndex, i));
-                savedIndex = i + 1;
-                if (char == '"'.charCodeAt(0)) {
-                    this.write('\\"');
-                } else if (char == "\\".charCodeAt(0)) {
-                    this.write("\\\\");
-                } else if (char == "\b".charCodeAt(0)) {
-                    this.write("\\b");
-                } else if (char == "\n".charCodeAt(0)) {
-                    this.write("\\n");
-                } else if (char == "\r".charCodeAt(0)) {
-                    this.write("\\r");
-                } else if (char == "\t".charCodeAt(0)) {
-                    this.write("\\t");
-                } else {
-                    // TODO: Implement encoding for other contol characters
-                    assert(false, "Unsupported control chracter");
-                }
-            }
-        }
-        this.write(str.substring(savedIndex, str.length));
-        this.write('"');
-    }
-
-    private writeBoolean(value: bool): void {
-        this.write(value ? "true" : "false");
-    }
-
-    private writeInteger(value: i32): void {
-        // TODO: More efficient encoding
-        let arr: Array<i32> = [value];
-        this.write(arr.toString());
-    }
-
-    private write(str: string): void {
-        this.result += str;
-    }
-}
-
-
 export class StringConversionTests {
-    private static handler : JSONTestHandler = new JSONTestHandler();
+    private static handler : JSONEncoder = null;
 
     static setUp(): void {
-        this.handler = new JSONTestHandler();
+        this.handler = new JSONEncoder();
     }
 
-    static createDecoder(): JSONDecoder<JSONTestHandler> {
+    static createDecoder(): JSONDecoder<JSONEncoder> {
         return new JSONDecoder(this.handler);
     }
 
@@ -208,24 +101,10 @@ export class StringConversionTests {
             buffer[i] = load<u8>(utf8ptr + i);
         }
         this.createDecoder().deserialize(buffer);
-        assert(this.handler.result == expectedString,
-            "Expected:\n" + expectedString + "\n" + "Actual:\n" + this.handler.result);
+        let resultBuffer = this.handler.serialize();
+        let resultString = String.fromUTF8(resultBuffer.buffer.data, resultBuffer.length);
+        assert(resultString == expectedString,
+            "Expected:\n" + expectedString + "\n" + "Actual:\n" + resultString)
         return true;
     }
-}
-
-function bytes2array(typedArr: Uint8Array): Array<u8> {
-    let arr = new Array<u8>();
-    for (let i = 0; i < typedArr.length; i++) {
-        arr.push(typedArr[i]);
-    }
-    return arr;
-}
-
-function hex2bin(hex: string): Uint8Array {
-    let bin = new Uint8Array(hex.length >>> 1);
-    for (let i = 0, len = hex.length >>> 1; i < len; i++) {
-        bin[i] = u32(parseInt(hex.substr(i << 1, 2), 16));
-    }
-    return bin;
 }
\ No newline at end of file