diff --git a/package-lock.json b/package-lock.json
index 22240adf..1ed34914 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "fluence",
-  "version": "0.7.103",
+  "version": "0.7.106",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index a6fa8bfd..d85b1b13 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fluence",
-  "version": "0.7.106",
+  "version": "0.7.107",
   "description": "the browser js-libp2p client for the Fluence network",
   "main": "./dist/fluence.js",
   "typings": "./dist/fluence.d.ts",
diff --git a/src/aqua/index.d.ts b/src/aqua/index.d.ts
index a80675aa..d51c0144 100644
--- a/src/aqua/index.d.ts
+++ b/src/aqua/index.d.ts
@@ -9,7 +9,7 @@
  * @param {string} log_level
  * @returns {string}
  */
-export function invoke(wasm: any, init_user_id: string, aqua: string, prev_data: string, data: string, log_level: string): string;
+export function invoke(wasm: any, init_user_id: string, aqua: string, prev_data: Uint8Array, data: Uint8Array, log_level: string): string;
 export function ast(wasm: any, script: string): string;
 export function return_current_peer_id(wasm: any, peerId: string, arg0: any): void;
 export function return_call_service_result(wasm: any, ret: string, arg0: any): void;
diff --git a/src/aqua/index_bg.js b/src/aqua/index_bg.js
index 4561bf0e..68c40f49 100644
--- a/src/aqua/index_bg.js
+++ b/src/aqua/index_bg.js
@@ -91,6 +91,14 @@ cachedTextDecoder.decode();
 export function getStringFromWasm0(wasm, ptr, len) {
     return cachedTextDecoder.decode(getUint8Memory0(wasm).subarray(ptr, ptr + len));
 }
+
+function passArray8ToWasm0(wasm, arg, malloc) {
+    const ptr = malloc(arg.length * 1);
+    getUint8Memory0(wasm).set(arg, ptr / 1);
+    WASM_VECTOR_LEN = arg.length;
+    return ptr;
+}
+
 /**
  * @param {any} wasm
  * @param {string} init_user_id
@@ -106,9 +114,9 @@ export function invoke(wasm, init_user_id, aqua, prev_data, data, log_level) {
         var len0 = WASM_VECTOR_LEN;
         var ptr1 = passStringToWasm0(wasm, aqua, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
         var len1 = WASM_VECTOR_LEN;
-        var ptr2 = passStringToWasm0(wasm, prev_data, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
+        var ptr2 = passArray8ToWasm0(wasm, prev_data, wasm.__wbindgen_malloc);
         var len2 = WASM_VECTOR_LEN;
-        var ptr3 = passStringToWasm0(wasm, data, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
+        var ptr3 = passArray8ToWasm0(wasm, data, wasm.__wbindgen_malloc);
         var len3 = WASM_VECTOR_LEN;
         var ptr4 = passStringToWasm0(wasm, log_level, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
         var len4 = WASM_VECTOR_LEN;
diff --git a/src/fluenceClient.ts b/src/fluenceClient.ts
index 64f18205..98960463 100644
--- a/src/fluenceClient.ts
+++ b/src/fluenceClient.ts
@@ -66,7 +66,7 @@ export class FluenceClient {
                     log.info(`Particle expired. Now: ${now}, ttl: ${particle.ttl}, ts: ${particle.timestamp}`);
                 } else {
                     // if there is no subscription yet, previous data is empty
-                    let prevData = [];
+                    let prevData: Uint8Array = Buffer.from([]);
                     let prevParticle = this.subscriptions.get(particle.id);
                     if (prevParticle) {
                         prevData = prevParticle.data;
@@ -79,8 +79,8 @@ export class FluenceClient {
                     let stepperOutcomeStr = this.interpreter(
                         particle.init_peer_id,
                         particle.script,
-                        JSON.stringify(prevData),
-                        JSON.stringify(particle.data),
+                        prevData,
+                        particle.data,
                     );
                     let stepperOutcome: StepperOutcome = JSON.parse(stepperOutcomeStr);
 
@@ -131,7 +131,7 @@ export class FluenceClient {
         let _this = this;
 
         return async (particle: Particle) => {
-            let data = particle.data;
+            let data: any = particle.data;
             let error: any = data['protocol!error'];
             if (error !== undefined) {
                 log.error('error in external particle: ');
diff --git a/src/fluenceConnection.ts b/src/fluenceConnection.ts
index ffb0a658..0cc3f996 100644
--- a/src/fluenceConnection.ts
+++ b/src/fluenceConnection.ts
@@ -23,7 +23,7 @@ import pipe from 'it-pipe';
 import Multiaddr from 'multiaddr';
 import PeerId from 'peer-id';
 import * as log from 'loglevel';
-import { build, parseParticle, Particle, stringifyParticle } from './particle';
+import { build, parseParticle, Particle, toAction } from './particle';
 
 export const PROTOCOL_NAME = '/fluence/faas/1.0.0';
 
@@ -121,8 +121,9 @@ export class FluenceConnection {
     async sendParticle(particle: Particle): Promise<void> {
         this.checkConnectedOrThrow();
 
-        let particleStr = stringifyParticle(particle);
-        log.debug('send particle: \n' + JSON.stringify(particle, undefined, 2));
+        let action = toAction(particle)
+        let particleStr = JSON.stringify(action);
+        log.debug('send particle: \n' + JSON.stringify(action, undefined, 2));
 
         // create outgoing substream
         const conn = (await this.node.dialProtocol(this.address, PROTOCOL_NAME)) as {
diff --git a/src/particle.ts b/src/particle.ts
index 699ded67..c3b0a6a1 100644
--- a/src/particle.ts
+++ b/src/particle.ts
@@ -15,6 +15,7 @@
  */
 
 import { v4 as uuidv4 } from 'uuid';
+import { fromByteArray } from 'base64-js';
 import PeerId from 'peer-id';
 import { encode } from 'bs58';
 import { addData } from './dataStorage';
@@ -29,7 +30,21 @@ export interface Particle {
     script: string;
     // sign upper fields
     signature: string;
-    data: any;
+    data: Uint8Array;
+}
+
+/**
+ * Represents particle action to send to a node
+ */
+interface ParticleAction {
+    action: 'Particle'
+    id: string;
+    init_peer_id: string;
+    timestamp: number;
+    ttl: number;
+    script: string;
+    signature: number[];
+    data: string;
 }
 
 function wrapScript(selfPeerId: string, script: string, fields: string[]): string {
@@ -63,7 +78,7 @@ export async function build(peerId: PeerId, script: string, data: Map<string, an
         ttl: ttl,
         script: script,
         signature: '',
-        data: [],
+        data: Buffer.from([]),
     };
 
     particle.signature = await signParticle(peerId, particle);
@@ -72,16 +87,20 @@ export async function build(peerId: PeerId, script: string, data: Map<string, an
 }
 
 /**
- * Copies a particle and stringify it.
+ * Creates an action to send to a node.
  */
-export function stringifyParticle(call: Particle): string {
-    let obj: any = { ...call };
-    obj.action = 'Particle';
-
-    // delete it after signatures will be implemented on nodes
-    obj.signature = [];
-
-    return JSON.stringify(obj);
+export function toAction(particle: Particle): ParticleAction {
+    return {
+        action: "Particle",
+        id: particle.id,
+        init_peer_id: particle.init_peer_id,
+        timestamp: particle.timestamp,
+        ttl: particle.ttl,
+        script: particle.script,
+        // TODO: copy signature from a particle after signatures will be implemented on nodes
+        signature: [],
+        data: fromByteArray(particle.data)
+    };
 }
 
 export function parseParticle(str: string): Particle {
diff --git a/src/stepper.ts b/src/stepper.ts
index f36f29b0..fbbf3ddf 100644
--- a/src/stepper.ts
+++ b/src/stepper.ts
@@ -26,7 +26,7 @@ import Instance = WebAssembly.Instance;
 import Exports = WebAssembly.Exports;
 import ExportValue = WebAssembly.ExportValue;
 
-export type InterpreterInvoke = (init_user_id: string, script: string, prev_data: string, data: string) => string;
+export type InterpreterInvoke = (init_user_id: string, script: string, prev_data: Uint8Array, data: Uint8Array) => string;
 type ImportObject = {
     './aquamarine_client_bg.js': {
         // fn call_service_impl(service_id: String, fn_name: String, args: String, security_tetraplets: String) -> String;
@@ -173,7 +173,7 @@ export async function instantiateInterpreter(peerId: PeerId): Promise<Interprete
     });
     let instance = await interpreterInstance(cfg);
 
-    return (init_user_id: string, script: string, prev_data: string, data: string) => {
+    return (init_user_id: string, script: string, prev_data: Uint8Array, data: Uint8Array) => {
         let logLevel = log.getLevel();
         let logLevelStr = 'info';
         if (logLevel === 0) {
diff --git a/src/stepperOutcome.ts b/src/stepperOutcome.ts
index ae674e69..9109d99e 100644
--- a/src/stepperOutcome.ts
+++ b/src/stepperOutcome.ts
@@ -16,6 +16,6 @@
 
 export interface StepperOutcome {
     ret_code: number;
-    data: number[];
+    data: Uint8Array;
     next_peer_pks: string[];
 }