diff --git a/src/transaction_builder.ts b/src/transaction_builder.ts
index ee3d894..22bcb21 100644
--- a/src/transaction_builder.ts
+++ b/src/transaction_builder.ts
@@ -18,9 +18,10 @@ import {
     toByteArray,
     uint8ArrayToHex
 } from "./utils.js";
+import TE from "./typed_encoding.js"
 import { deriveAddress, deriveKeyPair, sign } from "./crypto.js";
 
-const VERSION = 2
+const VERSION = 3
 
 function getTransactionTypeId(type: UserTypeTransaction): number {
     switch (type) {
@@ -359,10 +360,7 @@ export default class TransactionBuilder {
                     // address
                     address)
             } else {
-                // we need to order object keys ASC because that's what elixir does
-                const orderedArgs = args.map((arg) => sortObjectKeysASC(arg))
-                const jsonArgs = JSON.stringify(orderedArgs)
-                const bufJsonLength = toByteArray(jsonArgs.length)
+                const serializedArgs = args.map((arg) => TE.serialize(arg))
 
                 return concatUint8Arrays(
                     // 1 = named action
@@ -372,10 +370,10 @@ export default class TransactionBuilder {
                     // action
                     Uint8Array.from([action.length]),
                     new TextEncoder().encode(action),
+                    // args count
+                    Uint8Array.from([serializedArgs.length]),
                     // args
-                    Uint8Array.from([bufJsonLength.length]),
-                    bufJsonLength,
-                    new TextEncoder().encode(jsonArgs),
+                    ...serializedArgs
                 )
 
             }
diff --git a/src/typed_encoding.ts b/src/typed_encoding.ts
new file mode 100644
index 0000000..d19a9d2
--- /dev/null
+++ b/src/typed_encoding.ts
@@ -0,0 +1,166 @@
+import {
+    concatUint8Arrays,
+    toBigInt,
+    fromBigInt,
+    sortObjectKeysASC,
+    deserializeString,
+    serializeString,
+    nextUint8
+} from "./utils.js"
+
+import VarInt from "./varint.js"
+
+export default {
+    serialize,
+    deserialize
+}
+
+/**
+ * Serialize any data
+ * @param data
+ * @returns the data encoded
+ */
+function serialize(data: any, version: number = 1): Uint8Array {
+    // we need to order object keys ASC because that's what elixir does
+    data = sortObjectKeysASC(data)
+
+    switch (version) {
+        default:
+            return do_serialize_v1(data)
+    }
+}
+/**
+ * Deserialize an encoded data
+ * @param encoded_data
+ * @returns the data decoded
+ */
+function deserialize(encoded_data: Uint8Array, version: number = 1): any {
+    const iter = encoded_data.entries()
+
+    switch (version) {
+        default:
+            return do_deserialize_v1(iter)
+    }
+}
+
+
+const TYPE_INT = 0
+const TYPE_FLOAT = 1
+const TYPE_STR = 2
+const TYPE_LIST = 3
+const TYPE_MAP = 4
+const TYPE_BOOL = 5
+const TYPE_NIL = 6
+
+
+function do_serialize_v1(data: any): Uint8Array {
+    if (data === null) {
+        return Uint8Array.from([TYPE_NIL])
+    } else if (data === true) {
+        return Uint8Array.from([TYPE_BOOL, 1])
+    } else if (data === false) {
+        return Uint8Array.from([TYPE_BOOL, 0])
+    } else if (Number(data) === data) {
+        const sign = data >= 0
+
+        if (Number.isInteger(data)) {
+            return concatUint8Arrays(
+                Uint8Array.from([TYPE_INT]),
+                Uint8Array.from([sign ? 1 : 0]),
+                VarInt.serialize(Math.abs(data))
+            )
+        } else {
+            return concatUint8Arrays(
+                Uint8Array.from([TYPE_FLOAT]),
+                Uint8Array.from([sign ? 1 : 0]),
+                VarInt.serialize(toBigInt(Math.abs(data)))
+            )
+        }
+    } else if (typeof data === 'string') {
+        return concatUint8Arrays(
+            Uint8Array.from([TYPE_STR]),
+            VarInt.serialize(byte_size(data)),
+            serializeString(data)
+        )
+    } else if (Array.isArray(data)) {
+        const serializedItems = data.map((item) => do_serialize_v1(item))
+        return concatUint8Arrays(
+            Uint8Array.from([TYPE_LIST]),
+            VarInt.serialize(data.length),
+            ...serializedItems
+        )
+    } else if (typeof data == "object") {
+        const serializedKeyValues =
+            Object.keys(data)
+                .reduce(function (acc: Uint8Array[], key: any) {
+                    acc.push(do_serialize_v1(key))
+                    acc.push(do_serialize_v1(data[key]))
+                    return acc
+                }, []);
+
+        return concatUint8Arrays(
+            Uint8Array.from([TYPE_MAP]),
+            VarInt.serialize(Object.keys(data).length),
+            ...serializedKeyValues
+        )
+    } else {
+        throw new Error("Unhandled data type")
+    }
+}
+
+function do_deserialize_v1(iter: IterableIterator<[number, number]>): any {
+    switch (nextUint8(iter)) {
+        case TYPE_NIL:
+            return null
+
+        case TYPE_BOOL:
+            return nextUint8(iter) == 1
+
+        case TYPE_INT:
+            return nextUint8(iter) == 1
+                ? VarInt.deserialize(iter)
+                : VarInt.deserialize(iter) * -1
+
+        case TYPE_FLOAT:
+            return nextUint8(iter) == 1
+                ? fromBigInt(VarInt.deserialize(iter))
+                : fromBigInt(VarInt.deserialize(iter) * -1)
+
+
+        case TYPE_STR:
+            const strLen = VarInt.deserialize(iter)
+
+            let bytes = []
+            for (let i = 0; i < strLen; i++) {
+                bytes.push(nextUint8(iter))
+            }
+
+            return deserializeString(Uint8Array.from(bytes))
+
+        case TYPE_LIST:
+            const listLen = VarInt.deserialize(iter)
+
+            let list = []
+            for (let i = 0; i < listLen; i++) {
+                list.push(do_deserialize_v1(iter))
+            }
+
+            return list
+
+        case TYPE_MAP:
+            const keysLen = VarInt.deserialize(iter)
+
+            // we use a map here because keys can be of any type
+            let map = new Map()
+            for (let i = 0; i < keysLen; i++) {
+                map.set(do_deserialize_v1(iter), do_deserialize_v1(iter))
+            }
+
+            return Object.fromEntries(map.entries())
+
+    }
+}
+
+function byte_size(str: string) {
+    return (new TextEncoder().encode(str)).length
+}
\ No newline at end of file
diff --git a/src/utils.ts b/src/utils.ts
index 8c184e3..5df506c 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -45,6 +45,12 @@ export function sortObjectKeysASC(term: any): any {
     if (Array.isArray(term))
         return term.map((item: any) => sortObjectKeysASC(item))
 
+    if (term instanceof Map)
+        // we can't sort keys of a map
+        // because the keys aren't strings
+        // FIXME: this might cause an issue because elixir order & javascript order may differ
+        return term
+
     // object: sort and map over elements
     if (isObject(term))
         return Object.keys(term).sort().reduce((newObj: any, key: string) => {
@@ -206,12 +212,53 @@ export function base64url(arraybuffer: ArrayBuffer): string {
  * Convert any number into a byte array
  */
 export function toByteArray(number: number): Uint8Array {
-    if (!number) return Uint8Array.from([0]);
-    const a = [];
-    a.unshift(number & 255);
+    if (number === 0) return Uint8Array.from([0]);
+
+    const arr = [];
     while (number >= 256) {
-        number = number >>> 8;
-        a.unshift(number & 255);
+        arr.push(number % 256);
+        number = Math.floor(number / 256);
     }
-    return Uint8Array.from(a);
+
+    arr.push(number % 256)
+
+    return Uint8Array.from(arr.reverse());
+}
+
+/**
+ * Alias of uint8ArrayToInt
+ *
+ * @param bytes
+ * @returns the number
+ */
+export function fromByteArray(bytes: Uint8Array): number {
+    return uint8ArrayToInt(bytes)
+}
+
+/**
+ * Return the next Uint8 from an iterator of Uint8Array
+ * There is an assumption on success
+ * @param iter
+ * @returns
+ */
+export function nextUint8(iter: IterableIterator<[number, number]>): number {
+    return iter.next().value[1]
 }
+
+/**
+ * String to Uint8Array
+ * @param str
+ * @returns
+ */
+export function serializeString(str: string): Uint8Array {
+    return new TextEncoder().encode(str)
+}
+
+/**
+ * Uint8Array to String
+ * @param str
+ * @returns
+ */
+export function deserializeString(encoded_str: Uint8Array): string {
+    return new TextDecoder().decode(encoded_str)
+}
\ No newline at end of file
diff --git a/src/varint.ts b/src/varint.ts
new file mode 100644
index 0000000..4ee527c
--- /dev/null
+++ b/src/varint.ts
@@ -0,0 +1,26 @@
+import { toByteArray, concatUint8Arrays, nextUint8, fromByteArray } from "./utils.js"
+
+export default {
+    serialize,
+    deserialize
+}
+
+function serialize(int: number): Uint8Array {
+    const buff = toByteArray(int)
+
+    return concatUint8Arrays(
+        Uint8Array.from([buff.length]),
+        buff
+    )
+}
+
+function deserialize(iter: IterableIterator<[number, number]>): number {
+    const length = nextUint8(iter)
+
+    let bytes = []
+    for (let i = 0; i < length; i++) {
+        bytes.push(nextUint8(iter))
+    }
+
+    return fromByteArray(Uint8Array.from(bytes))
+}
\ No newline at end of file
diff --git a/tests/transaction_builder.test.ts b/tests/transaction_builder.test.ts
index c12831f..c2657a2 100644
--- a/tests/transaction_builder.test.ts
+++ b/tests/transaction_builder.test.ts
@@ -9,6 +9,9 @@ import {
     uint8ArrayToHex,
 } from "../src/utils";
 import { Curve } from "../src/types";
+import TE from "../src/typed_encoding";
+
+const VERSION = 3
 
 // all assert should be transformed to jest expect
 describe("Transaction builder", () => {
@@ -207,7 +210,7 @@ describe("Transaction builder", () => {
 
             const expected_binary = concatUint8Arrays(
                 //Version
-                intToUint8Array(2),
+                intToUint8Array(VERSION),
                 tx.address,
                 Uint8Array.from([253]),
                 //Code size
@@ -327,7 +330,7 @@ describe("Transaction builder", () => {
 
             const expected_binary = concatUint8Arrays(
                 //Version
-                intToUint8Array(2),
+                intToUint8Array(VERSION),
                 tx.address,
                 Uint8Array.from([253]),
                 //Code size
@@ -395,13 +398,10 @@ describe("Transaction builder", () => {
                 Uint8Array.from([14]),
                 // action value
                 new TextEncoder().encode("vote_for_mayor"),
-                // args
-                // args size bytes
-                Uint8Array.from([1]),
                 // args size
-                Uint8Array.from([13]),
+                Uint8Array.from([1]),
                 // args value
-                new TextEncoder().encode("[\"Ms. Smith\"]"),
+                TE.serialize("Ms. Smith")
             );
             expect(payload).toEqual(expected_binary);
 
@@ -424,7 +424,7 @@ describe("Transaction builder", () => {
 
             const expected_binary = concatUint8Arrays(
                 //Version
-                intToUint8Array(2),
+                intToUint8Array(VERSION),
                 tx.address,
                 Uint8Array.from([253]),
                 //Code size
@@ -457,13 +457,10 @@ describe("Transaction builder", () => {
                 Uint8Array.from([10]),
                 // action value
                 new TextEncoder().encode("set_geopos"),
-                // args
-                // args size bytes
-                Uint8Array.from([1]),
                 // args size
-                Uint8Array.from([19]),
+                Uint8Array.from([1]),
                 // args value
-                new TextEncoder().encode(`[{"lat":1,"lng":2}]`),
+                TE.serialize({ "lng": 2, "lat": 1 })
             );
             expect(payload).toEqual(expected_binary);
 
@@ -585,7 +582,7 @@ describe("Transaction builder", () => {
             const payload = tx.originSignaturePayload();
             const expected_binary = concatUint8Arrays(
                 //Version
-                intToUint8Array(2),
+                intToUint8Array(VERSION),
                 tx.address,
                 Uint8Array.from([253]),
                 //Code size
@@ -750,7 +747,7 @@ describe("Transaction builder", () => {
             const txRPC = tx.toRPC();
 
             // @ts-ignore
-            expect(txRPC.version).toStrictEqual(2);
+            expect(txRPC.version).toStrictEqual(VERSION);
             // @ts-ignore
             expect(txRPC.data.ledger.uco.transfers[0]).toStrictEqual(
                 {
diff --git a/tests/typed_encoding.test.ts b/tests/typed_encoding.test.ts
new file mode 100644
index 0000000..c1d4bed
--- /dev/null
+++ b/tests/typed_encoding.test.ts
@@ -0,0 +1,34 @@
+import TE from "../src/typed_encoding"
+
+describe("TE", () => {
+    it("should serialize/deserialize a null", () => {
+        expect(TE.deserialize(TE.serialize(null))).toBeNull()
+    })
+    it("should serialize/deserialize a bool", () => {
+        expect(TE.deserialize(TE.serialize(true))).toBe(true)
+        expect(TE.deserialize(TE.serialize(false))).toBe(false)
+    })
+    it("should serialize/deserialize an integer", () => {
+        expect(TE.deserialize(TE.serialize(0))).toBe(0)
+        expect(TE.deserialize(TE.serialize(1))).toBe(1)
+        expect(TE.deserialize(TE.serialize(2 ** 40))).toBe(2 ** 40)
+    })
+    it("should serialize/deserialize a float", () => {
+        expect(TE.deserialize(TE.serialize(1.00000001))).toBe(1.00000001)
+        expect(TE.deserialize(TE.serialize(1.99999999))).toBe(1.99999999)
+    })
+    it("should serialize/deserialize a str", () => {
+        expect(TE.deserialize(TE.serialize("hello"))).toBe("hello")
+        expect(TE.deserialize(TE.serialize("world"))).toBe("world")
+        expect(TE.deserialize(TE.serialize("un été à l'ombre"))).toBe("un été à l'ombre")
+    })
+    it("should serialize/deserialize a list", () => {
+        expect(TE.deserialize(TE.serialize([]))).toStrictEqual([])
+        expect(TE.deserialize(TE.serialize([1, 2, 3]))).toStrictEqual([1, 2, 3])
+        expect(TE.deserialize(TE.serialize(["1", true, 14]))).toStrictEqual(["1", true, 14])
+    })
+    it("should serialize/deserialize an object", () => {
+        expect(TE.deserialize(TE.serialize({}))).toStrictEqual({})
+        expect(TE.deserialize(TE.serialize({ a: 1, foo: "bar" }))).toStrictEqual({ a: 1, foo: "bar" })
+    })
+})
diff --git a/tests/utils.test.ts b/tests/utils.test.ts
index 63cc39b..8ea74cc 100644
--- a/tests/utils.test.ts
+++ b/tests/utils.test.ts
@@ -8,7 +8,8 @@ import {
     toByteArray,
     toBigInt,
     fromBigInt,
-    sortObjectKeysASC
+    sortObjectKeysASC,
+    uint8ArrayToInt
 } from "../src/utils.js"
 
 describe("Utils", () => {
@@ -67,10 +68,32 @@ describe("Utils", () => {
     describe("toByteArray", () => {
         it("should encode an integer into a UnInt8Array", () => {
             expect(toByteArray(0)).toStrictEqual(new Uint8Array([0]))
-            expect(toByteArray(123)).toStrictEqual(new Uint8Array([123]))
-            expect(toByteArray(258)).toStrictEqual(new Uint8Array([1, 2]))
-            expect(toByteArray(65535)).toStrictEqual(new Uint8Array([255, 255]))
-            expect(toByteArray(65536)).toStrictEqual(new Uint8Array([1, 0, 0]))
+            expect(toByteArray(2 ** 8 - 1)).toStrictEqual(new Uint8Array([255]))
+            expect(toByteArray(2 ** 8)).toStrictEqual(new Uint8Array([1, 0]))
+            expect(toByteArray(2 ** 16 - 1)).toStrictEqual(new Uint8Array([255, 255]))
+            expect(toByteArray(2 ** 16)).toStrictEqual(new Uint8Array([1, 0, 0]))
+            expect(toByteArray(2 ** 24 - 1)).toStrictEqual(new Uint8Array([255, 255, 255]))
+            expect(toByteArray(2 ** 24)).toStrictEqual(new Uint8Array([1, 0, 0, 0]))
+            expect(toByteArray(2 ** 32 - 1)).toStrictEqual(new Uint8Array([255, 255, 255, 255]))
+            expect(toByteArray(2 ** 32)).toStrictEqual(new Uint8Array([1, 0, 0, 0, 0]))
+            expect(toByteArray(2 ** 40 - 1)).toStrictEqual(new Uint8Array([255, 255, 255, 255, 255]))
+            expect(toByteArray(2 ** 40)).toStrictEqual(new Uint8Array([1, 0, 0, 0, 0, 0]))
+        })
+    })
+
+    describe("uint8ArrayToInt / fromByteArray", () => {
+        it("should decode an integer from a UnInt8Array", () => {
+            expect(uint8ArrayToInt(new Uint8Array([0]))).toStrictEqual(0)
+            expect(uint8ArrayToInt(new Uint8Array([255]))).toStrictEqual(2 ** 8 - 1)
+            expect(uint8ArrayToInt(new Uint8Array([1, 0]))).toStrictEqual(2 ** 8)
+            expect(uint8ArrayToInt(new Uint8Array([255, 255]))).toStrictEqual(2 ** 16 - 1)
+            expect(uint8ArrayToInt(new Uint8Array([1, 0, 0]))).toStrictEqual(2 ** 16)
+            expect(uint8ArrayToInt(new Uint8Array([255, 255, 255]))).toStrictEqual(2 ** 24 - 1)
+            expect(uint8ArrayToInt(new Uint8Array([1, 0, 0, 0]))).toStrictEqual(2 ** 24)
+            expect(uint8ArrayToInt(new Uint8Array([255, 255, 255, 255]))).toStrictEqual(2 ** 32 - 1)
+            expect(uint8ArrayToInt(new Uint8Array([1, 0, 0, 0, 0]))).toStrictEqual(2 ** 32)
+            expect(uint8ArrayToInt(new Uint8Array([255, 255, 255, 255, 255]))).toStrictEqual(2 ** 40 - 1)
+            expect(uint8ArrayToInt(new Uint8Array([1, 0, 0, 0, 0, 0]))).toStrictEqual(2 ** 40)
         })
     })
 
diff --git a/tests/varint.test.ts b/tests/varint.test.ts
new file mode 100644
index 0000000..ffd61e5
--- /dev/null
+++ b/tests/varint.test.ts
@@ -0,0 +1,17 @@
+import VarInt from "../src/varint"
+
+describe("VarInt", () => {
+    it("should serialize/deserialize", () => {
+        expect(VarInt.deserialize(VarInt.serialize(0).entries())).toBe(0)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 8 - 1).entries())).toBe(2 ** 8 - 1)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 8).entries())).toBe(2 ** 8)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 16 - 1).entries())).toBe(2 ** 16 - 1)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 16).entries())).toBe(2 ** 16)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 24 - 1).entries())).toBe(2 ** 24 - 1)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 24).entries())).toBe(2 ** 24)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 32 - 1).entries())).toBe(2 ** 32 - 1)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 32).entries())).toBe(2 ** 32)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 40 - 1).entries())).toBe(2 ** 40 - 1)
+        expect(VarInt.deserialize(VarInt.serialize(2 ** 40).entries())).toBe(2 ** 40)
+    })
+})
\ No newline at end of file