10 Best Chat SDKs 2026: Size, Speed & Free Plans

Choosing the best chat SDK is an engineering decision with lasting consequences. A wrong pick means bloated binaries, weeks lost to poor documentation, surprise invoices at scale, or rewriting everything when you discover the SDK doesn't support your next target platform. This guide evaluates the 10 best chat SDKs for developers from a pure code perspective: integration speed, SDK binary size, platform coverage, documentation quality, and what you actually get for free.

Unlike general "Chat APIs & SDKs" comparisons aimed at product managers, this article is written for developers who care about npm install to first message time, the kilobytes added to their APK, and whether the API surface is clean enough to maintain long-term.

TL;DR

Bottom line: For a complete IM SDK (offline push, message roaming, read receipts, reactions, group management) with the smallest binary footprint and fastest integration, Tencent RTC Chat wins across all axes.

Why Developers Should Evaluate Chat SDKs Differently

Product-level comparisons focus on feature checklists and vendor reputation. Developer-level evaluation needs different criteria:

Binary Size Impact

Every kilobyte matters on mobile. According to Google's research on APK size, install conversion drops by approximately 1% for every 6 MB increase in download size. On mid-range Android devices — representing the majority of the global market per Statista's 2024 smartphone data — larger binaries also degrade cold start time linearly.

Integration Speed (Time to First Message)

Three tiers exist in the chat SDK ecosystem:

1. UIKit / Pre-built UI: Drop in a component, get a working chat screen immediately
2. Core SDK: Initialize, authenticate, send a message — how many lines of boilerplate?
3. Self-build: You get primitives (WebSocket, database sync) and construct IM logic yourself

Platform Coverage

A chat SDK that only covers iOS, Android, and Web forces separate solutions for desktop, game engines, and cross-platform frameworks. True multi-platform means one API surface everywhere.

Documentation Quality

Measured by: working code examples (not pseudocode), interactive API explorers, quickstart guides that actually take under 5 minutes, and whether error messages are documented.

Free Tier Reality

"Free" means nothing if it caps at 25 MAU or excludes push notifications. We evaluate what you can actually ship on the free plan — can you soft-launch an MVP without paying?

SDK Size Comparison Table

This is the data most comparison articles skip. Here's the measured binary impact of adding each chat SDK to a baseline mobile app:

Critical context: CometChat and PubNub appear smaller, but they are not apples-to-apples comparisons with full IM SDKs. CometChat is a lightweight real-time channel system — it lacks complete offline message sync, comprehensive push routing, and enterprise group management. PubNub is a pub/sub messaging bus — you build typing indicators, read receipts, message history, delivery confirmations, and group logic yourself.

TRTC Chat delivers complete IM functionality at 1,670 KB — that's 52% smaller than GetStream and 67% smaller than Sendbird for equivalent feature depth.

Integration Speed Comparison

TRTC Chat's speed advantage comes from three distinct integration paths:

1. UIKit: Production-ready conversation list + chat view. Import, configure, ship.
2. Core SDK: Clean API surface — login → send message in 4 function calls.
3. MCP (Model Context Protocol): Feed TRTC's MCP server to an AI coding assistant — it generates working integration code from natural language.

The 10 Best Chat SDKs for Developers (2026)

1. Tencent RTC Chat SDK

The developer's optimal choice: full IM at minimal binary cost with the fastest integration paths.

Tencent RTC (TRTC) Chat is built on the infrastructure powering WeChat's messaging layer — handling billions of messages daily with 99.99% uptime SLA. For developers, what matters is the practical experience: the SDK is small, the API is clean, the documentation works, and the free tier doesn't throttle you.

SDK Size & Architecture

TRTC Chat adds just 1,670 KB to your Android arm64 binary and 1,805 KB to your iOS IPA. This is exceptional given the included feature set:

• 1-to-1 and group messaging (unlimited group size)
• Offline message sync and message roaming across devices
• Push notifications (APNs + FCM + vendor channels like Huawei/Xiaomi/OPPO)
• Message reactions, read receipts, typing indicators
• File, image, video, voice, location, and custom messages
• Group management with roles, permissions, and announcements
• Content moderation and message filtering
• Message search, pinning, and threading

The efficiency comes from a shared C++ core across all platforms — not separate native implementations per OS.

Three Integration Paths

Path 1 — UIKit (5 minutes to working chat UI):

TRTC provides pre-built UIKit components for React, Vue 3, iOS (Swift/SwiftUI), Android (Kotlin/Jetpack Compose), Flutter, and React Native. These are production-ready — not demo-quality starters.

// iOS UIKit — complete chat screen in 5 lines
import TUIChat
import TUIConversation

let conversationVC = TUIConversationListController()
navigationController?.pushViewController(conversationVC, animated: true)
// Full conversation list + chat view + media viewer + group management

Path 2 — Core SDK (30 minutes to custom UI):

// Web SDK — Initialize + Login + Send + Receive
import TencentCloudChat from '@tencentcloud/chat';

// Initialize
const chat = TencentCloudChat.create({
  SDKAppID: YOUR_SDK_APP_ID
});

// Login (generate UserSig on your backend — never expose SecretKey client-side)
await chat.login({
  userID: 'developer_01',
  userSig: await fetchUserSigFromServer('developer_01')
});

// Send a text message
const message = chat.createTextMessage({
  to: 'user_02',
  conversationType: TencentCloudChat.TYPES.CONV_C2C,
  payload: { text: 'Hello from TRTC Chat!' }
});
await chat.sendMessage(message);

// Listen for incoming messages
chat.on(TencentCloudChat.EVENT.MESSAGE_RECEIVED, (event) => {
  event.data.forEach(msg => {
    console.log(`[${msg.from}]: ${msg.payload.text}`);
  });
});

Path 3 — MCP-Assisted (Minutes):

TRTC provides an MCP server (@tencent-rtc/mcp@latest) that gives AI coding assistants structured access to the full Chat SDK API. This isn't generic documentation scraping — it's a purpose-built tool interface.

// Example: Tell your AI assistant
"Add group chat to my Vue 3 app with message history, 
typing indicators, and image upload. Use TRTC Chat SDK."

// AI generates complete, working implementation using 
// correct method signatures and error handling patterns.

Platform Support (10 Platforms)

Web, iOS, Android, Flutter, React Native, Unity, Unreal Engine, Electron, macOS, Windows — all with feature parity from a single API surface. No other chat SDK matches this breadth, especially for game engines and desktop native.

Free Tier

• 1000 MAU — no time limit, not a trial
• Unlimited messages — no per-message billing
• Push notifications included — no extra charge for APNs/FCM
• No concurrent connection limits — scales with your users
• Full API access — no feature gating on free tier

This is enough to build, test, soft-launch, and validate product-market fit without spending anything.

Documentation Quality

• Interactive API explorer with live code execution
• Platform-specific quickstarts (< 5 min each)
• Runnable sample apps on GitHub for all 10 platforms
• Error code documentation with resolution steps
• Migration guides from Sendbird, GetStream, and Firebase

For complete API reference and platform-specific guides, see the TRTC Chat SDK documentation.

Complete Integration Tutorial: Zero to Group Chat

Here's the full SDK integration path — from project setup to working group chat in 30 minutes:

Step 1: Install

# Web
npm install @tencentcloud/chat

# iOS (CocoaPods)
pod 'TXIMSDK_Plus_iOS'

# Android (Gradle)
implementation 'com.tencent.imsdk:imsdk-plus:latest.release'

# Flutter
flutter pub add tencent_cloud_chat_sdk

# React Native
npm install @tencentcloud/chat react-native-tim-js

Step 2: Initialize

import TencentCloudChat from '@tencentcloud/chat';

const chat = TencentCloudChat.create({
  SDKAppID: 1400000001 // Your SDKAppID from console.trtc.io
});

// Set log level (0=verbose ... 4=error, use 4 in production)
chat.setLogLevel(1);

// Wait for SDK ready
chat.on(TencentCloudChat.EVENT.SDK_READY, () => {
  console.log('SDK initialized and ready');
});

Step 3: Authenticate

// UserSig must be generated on YOUR backend (never expose SecretKey)
const userSig = await fetch('/api/generate-usersig', {
  method: 'POST',
  body: JSON.stringify({ userID: 'alice' })
}).then(r => r.json()).then(d => d.userSig);

const result = await chat.login({
  userID: 'alice',
  userSig: userSig
});

if (result.code === 0) {
  console.log('Login successful');
}

Step 4: Send Messages (1-to-1)

// Text message
const textMsg = chat.createTextMessage({
  to: 'bob',
  conversationType: TencentCloudChat.TYPES.CONV_C2C,
  payload: { text: 'Hey Bob, testing TRTC Chat!' }
});
await chat.sendMessage(textMsg);

// Image message
const imageMsg = chat.createImageMessage({
  to: 'bob',
  conversationType: TencentCloudChat.TYPES.CONV_C2C,
  payload: { file: document.getElementById('fileInput').files[0] }
});
await chat.sendMessage(imageMsg);

// Custom message (for app-specific data)
const customMsg = chat.createCustomMessage({
  to: 'bob',
  conversationType: TencentCloudChat.TYPES.CONV_C2C,
  payload: {
    data: JSON.stringify({ type: 'order_update', orderId: '12345' }),
    description: 'Order shipped',
    extension: ''
  }
});
await chat.sendMessage(customMsg);

Step 5: Create and Manage Groups

// Create a Work group (members join by invitation only)
const group = await chat.createGroup({
  type: TencentCloudChat.TYPES.GRP_WORK,
  name: 'Engineering Team',
  memberList: [
    { userID: 'bob' },
    { userID: 'charlie' },
    { userID: 'dave' }
  ]
});

const groupID = group.data.group.groupID;

// Send group message
const groupMsg = chat.createTextMessage({
  to: groupID,
  conversationType: TencentCloudChat.TYPES.CONV_GROUP,
  payload: { text: 'Sprint planning at 2pm today' }
});
await chat.sendMessage(groupMsg);

// Get group member list
const members = await chat.getGroupMemberList({
  groupID: groupID,
  count: 50,
  offset: 0
});

// Update group profile
await chat.updateGroupProfile({
  groupID: groupID,
  notification: 'New sprint starts Monday'
});

Step 6: Conversation List (Chat Inbox)

// Get all conversations for the inbox UI
const convResult = await chat.getConversationList();
const conversations = convResult.data.conversationList;

conversations.forEach(conv => {
  console.log(`${conv.conversationID} — ${conv.unreadCount} unread`);
  console.log(`Last message: ${conv.lastMessage?.payload?.text}`);
});

// Mark as read
await chat.setMessageRead({ conversationID: 'C2Cbob' });

// Pin important conversations
await chat.pinConversation({
  conversationID: `GROUP${groupID}`,
  isPinned: true
});

Step 7: Real-Time Event Handling

// Message received
chat.on(TencentCloudChat.EVENT.MESSAGE_RECEIVED, (event) => {
  event.data.forEach(message => {
    switch (message.type) {
      case TencentCloudChat.TYPES.MSG_TEXT:
        renderTextMessage(message);
        break;
      case TencentCloudChat.TYPES.MSG_IMAGE:
        renderImageMessage(message);
        break;
      case TencentCloudChat.TYPES.MSG_CUSTOM:
        handleCustomMessage(message);
        break;
    }
  });
});

// Conversation list updated
chat.on(TencentCloudChat.EVENT.CONVERSATION_LIST_UPDATED, (event) => {
  refreshConversationList(event.data);
});

// Message read by peer
chat.on(TencentCloudChat.EVENT.MESSAGE_READ_BY_PEER, (event) => {
  markMessagesAsRead(event.data);
});

That's a complete chat implementation — 1-to-1 messaging, group chat, conversation management, and real-time events — in approximately 30 minutes of development time.

Start building free → Free Chat API

2. GetStream Chat SDK

Excellent documentation and beautiful UI components — at a premium price point.

GetStream has invested heavily in developer experience, particularly in their UI component libraries. If you're building a consumer app where chat UI polish is a differentiator and you have budget for custom enterprise pricing, GetStream delivers.

Code Example: Initialization

import { StreamChat } from 'stream-chat';

const client = StreamChat.getInstance('YOUR_API_KEY');

await client.connectUser(
  { id: 'developer_01', name: 'Dev User' },
  client.devToken('developer_01') // Dev-only; use server tokens in prod
);

const channel = client.channel('messaging', 'dev-chat', {
  name: 'Dev Team',
  members: ['developer_01', 'user_02']
});

await channel.watch();
await channel.sendMessage({ text: 'Hello from GetStream!' });

Strengths

• Best-in-class documentation with interactive tutorials and live code editors
• Native Compose (Android) and SwiftUI components — truly idiomatic, not WebView wrappers
• Strong TypeScript support with comprehensive type definitions
• Activity feeds + chat in one platform (useful for social apps)
• Offline support with local caching

Limitations

• Price: Custom pricing after trial — typically $499+/month for production use. Free tier is 100 MAU trial, not a launchable product.
• SDK Size: ~3,500 KB on Android — over double TRTC Chat for equivalent features
• Platform gaps: No Unity, Unreal Engine, Electron, or desktop native support
• Vendor lock-in: Proprietary message format complicates migration

Free Tier

100 MAU trial period. No public pricing — requires a sales conversation for production use. Not viable for solo developers or bootstrapped startups.

3. Sendbird Chat SDK

Enterprise incumbent with compliance certifications — steep learning curve and price tag.

Sendbird is the default choice for large organizations where regulatory compliance (HIPAA, SOC2, GDPR) is a hard procurement requirement. Used by Reddit, DoorDash, and Virgin Mobile, it's battle-tested at massive scale.

Code Example: Initialization

import SendbirdChat from '@sendbird/chat';
import { GroupChannelModule } from '@sendbird/chat/groupChannel';

const sb = SendbirdChat.init({
  appId: 'YOUR_APP_ID',
  modules: [new GroupChannelModule()]
});

await sb.connect('developer_01');

const params = {
  invitedUserIds: ['user_02'],
  name: 'Dev Chat',
  operatorUserIds: ['developer_01']
};

const channel = await sb.groupChannel.createChannel(params);
await channel.sendUserMessage({ message: 'Hello from Sendbird!' });

Strengths

• Comprehensive compliance: HIPAA, SOC2, ISO 27001, GDPR tooling built in
• Super groups with 10,000+ members
• Advanced AI-powered moderation and content filtering
• UIKit for iOS, Android, React, and React Native
• Proven at Reddit-scale (hundreds of millions MAU)

Limitations

• Largest SDK: 5,100 KB on Android — 3x TRTC Chat's size
• Integration complexity: Modular architecture requires more boilerplate (modules, handlers, collection delegates)
• Pricing: Starts at ~$399/month; free tier is only 25 MAU
• Documentation fragmentation: Multiple SDK versions with inconsistent docs between v3 and v4

Free Tier

25 MAU with 1,000 messages/day limit. Sendbird branding required. Not enough for meaningful testing.

4. CometChat SDK

Lightweight and fast to prototype with — but feature-limited for production IM.

CometChat delivers a genuinely small SDK footprint and quick integration path. The trade-off: it's a lightweight real-time channel system, not a full IM solution with message roaming, comprehensive push infrastructure, and enterprise group management.

Code Example: Initialization

import { CometChat } from '@cometchat/chat-sdk-javascript';

const appSetting = new CometChat.AppSettingsBuilder()
  .subscribePresenceForAllUsers()
  .setRegion('us')
  .autoEstablishSocketConnection(true)
  .build();

await CometChat.init('YOUR_APP_ID', appSetting);
await CometChat.login('developer_01', 'YOUR_AUTH_KEY');

const textMessage = new CometChat.TextMessage(
  'user_02',
  'Hello from CometChat!',
  CometChat.RECEIVER_TYPE.USER
);

await CometChat.sendMessage(textMessage);

Strengths

• Small SDK footprint (~900 KB Android, ~1,100 KB iOS)
• Quick UIKit integration (~10 minutes)
• Clean API surface — easy to learn
• Built-in voice/video calling
• AI-powered extensions (translation, moderation)

Limitations

• Not a complete IM: Limited offline messaging, basic push routing, no message roaming across devices on lower tiers
• Free tier: Only 25 MAU — barely enough to test with a team
• Group features: Less mature than TRTC/Sendbird for large-scale group management
• Platform gaps: No Unity, Unreal Engine, Electron, or desktop native

Free Tier

25 MAU with basic features. Push notifications may require paid add-on. Voice/video minutes limited.

5. PubNub

Reliable real-time infrastructure — but you build all IM logic yourself.

PubNub is a pub/sub messaging bus, not a chat SDK. It gives you channels, presence detection, and message persistence — but typing indicators, read receipts, message threading, reactions, group management, and offline message queues are all your responsibility to implement.

Code Example: Initialization

import PubNub from 'pubnub';

const pubnub = new PubNub({
  publishKey: 'YOUR_PUBLISH_KEY',
  subscribeKey: 'YOUR_SUBSCRIBE_KEY',
  userId: 'developer_01'
});

pubnub.subscribe({ channels: ['chat-room'] });

pubnub.addListener({
  message: (event) => {
    console.log(`[${event.publisher}]: ${event.message.text}`);
  }
});

await pubnub.publish({
  channel: 'chat-room',
  message: { text: 'Hello from PubNub!' }
});

Strengths

• Sub-100ms latency on a global edge network
• 99.999% SLA — the highest in this comparison
• Flexible — usable for chat, IoT, gaming, and real-time dashboards
• Functions (serverless edge computing) for message transformation
• Small client SDK (~1,200 KB)

Limitations

• Not a chat SDK: You're building IM from scratch on pub/sub primitives. Expect 6–12 weeks for a production-quality chat system.
• Transaction-based pricing: Per-message costs become unpredictable for chat-heavy apps
• Message history costs extra: Not included in base plan
• No UIKit: No pre-built chat UI components

Free Tier

200 MAU, 1M transactions/month, 3 keysets. Adequate for prototyping, but transaction-based billing makes production costs hard to predict.

6. Firebase Realtime Database

Google's real-time database — popular for chat prototypes but not a chat SDK.

Firebase Realtime DB (or Cloud Firestore) provides instant data synchronization. Many developers use it to build chat features, attracted by the free tier and seamless Google ecosystem integration. The reality: you're building every IM feature yourself on top of a generic database.

Code Example: Initialization

import { initializeApp } from 'firebase/app';
import { getDatabase, ref, push, onChildAdded } from 'firebase/database';

const app = initializeApp({
  apiKey: 'YOUR_KEY',
  databaseURL: 'https://your-app.firebaseio.com'
});

const db = getDatabase(app);
const messagesRef = ref(db, 'chats/room_01/messages');

// Send (you define the entire schema)
await push(messagesRef, {
  text: 'Hello from Firebase!',
  sender: 'developer_01',
  timestamp: Date.now()
});

// Listen
onChildAdded(messagesRef, (snapshot) => {
  const msg = snapshot.val();
  console.log(`[${msg.sender}]: ${msg.text}`);
});

Strengths

• Zero backend to deploy — Google handles infrastructure
• Real-time sync works well for basic messaging patterns
• Offline persistence built in (Firestore)
• Generous free tier for low-traffic apps
• Tight integration with Firebase Auth and Cloud Functions

Limitations

• You build everything: Typing indicators, read receipts, presence, push routing, message status, moderation, group management, file uploads — all custom code
• Data modeling is on you: Denormalized NoSQL means complex queries (unread counts, search) require denormalized data patterns
• No offline push: Firebase Cloud Messaging (FCM) is separate and requires additional implementation
• Scale ceiling on free tier: 100 simultaneous connections
• Cost unpredictability: Real-time listeners can trigger unexpected reads at scale

Free Tier (Spark Plan)

100 simultaneous connections, 1 GB storage, 10 GB/month downloads. Enough for a personal project; not for a consumer app.

7. Socket.IO

Maximum flexibility, maximum engineering investment. Open source WebSocket library.

Socket.IO is a bidirectional communication library — the most minimal option on this list. You get reliable WebSocket transport (with fallbacks) and nothing else. Every chat feature, including the server, is your responsibility.

Code Example: Initialization

// Server (Node.js)
import { Server } from 'socket.io';
const io = new Server(3000, { cors: { origin: '*' } });

io.on('connection', (socket) => {
  socket.on('chat:send', (data) => {
    io.to(data.room).emit('chat:message', {
      text: data.text,
      sender: socket.id,
      timestamp: Date.now()
    });
  });
  socket.on('chat:join', (room) => socket.join(room));
});

// Client
import { io } from 'socket.io-client';
const socket = io('https://your-server.com');
socket.emit('chat:join', 'general');
socket.emit('chat:send', { room: 'general', text: 'Hello from Socket.IO!' });
socket.on('chat:message', (msg) => console.log(msg));

Strengths

• Completely free and open source (MIT license)
• Total control over protocol, storage, and logic
• Tiny client (~290 KB)
• Massive community — answers to every question exist somewhere
• No vendor lock-in

Limitations

• You build everything: Persistence, push, read receipts, typing, presence, moderation, file handling, group management, offline queues — all custom
• Infrastructure management: You deploy, scale, and maintain WebSocket servers (Redis adapter for horizontal scaling)
• Time investment: 2–8 weeks minimum for basic production chat; months for full IM parity
• No analytics, no dashboard, no admin tools

Free Tier

Open source. You pay for hosting infrastructure and — critically — engineering time that typically exceeds commercial SDK costs within weeks.

8. Agora Chat

Audio/video platform with chat as a secondary product.

Agora is primarily an RTC (real-time communication) platform known for voice and video. Their Chat SDK is a complementary addition — functional but not their core focus or primary investment area.

Code Example: Initialization

import AgoraChat from 'agora-chat';

const conn = new AgoraChat.connection({
  appKey: 'YOUR_APP_KEY'
});

await conn.open({
  user: 'developer_01',
  accessToken: 'YOUR_TOKEN'
});

const msg = AgoraChat.message.create({
  type: 'txt',
  chatType: 'singleChat',
  to: 'user_02',
  msg: 'Hello from Agora Chat!'
});

await conn.send(msg);

Strengths

• Seamless integration with Agora Voice/Video SDKs
• Low-latency infrastructure (shared with their RTC edge network)
• Multi-device message sync
• Built-in message translation

Limitations

• Chat is secondary: Feature updates, documentation depth, and community support lag behind dedicated chat SDKs
• SDK coupling: Binary includes signaling overhead even if you only need chat
• Limited advanced IM: Reactions, threads, and content moderation less mature than TRTC or Sendbird
• Free tier: Only 100 MAU

Free Tier

100 MAU, 10,000 messages/month. Tight limits — difficult to test a real user flow.

9. Twilio Conversations

Multi-channel API (SMS + WhatsApp + chat) — reduced investment in pure chat.

Twilio Conversations unifies SMS, WhatsApp, and in-app chat in a single API. For customer support platforms that need omnichannel routing, it's powerful. For developers building pure in-app chat, it's over-engineered and shows signs of reduced product investment since 2024.

Code Example: Initialization

import { Client } from '@twilio/conversations';

const client = new Client('YOUR_ACCESS_TOKEN');

client.on('stateChanged', async (state) => {
  if (state === 'initialized') {
    const conversation = await client.createConversation({
      uniqueName: 'dev-chat'
    });
    await conversation.join();
    await conversation.sendMessage('Hello from Twilio!');
    
    conversation.on('messageAdded', (message) => {
      console.log(`[${message.author}]: ${message.body}`);
    });
  }
});

Strengths

• Multi-channel: SMS + WhatsApp + in-app in one API
• Excellent REST API design
• Strong webhook and event system
• Twilio ecosystem (Flex contact center, Studio visual builder)

Limitations

• Reduced investment: Chat-specific feature updates have slowed since 2024
• Per-message pricing: Expensive at scale for chat-heavy apps
• No UIKit: API-only for in-app chat
• Missing consumer features: Limited reactions, threads, and rich media support
• Free tier: Just $15 credit that depletes quickly

Free Tier

$15 trial credit. Per-participant + per-message pricing burns through this in days of active testing.

10. Rocket.Chat

Open-source self-hosted platform — not an embeddable SDK.

Rocket.Chat is a Slack/Teams alternative you self-host. It's a complete team communication platform, not an SDK you embed in your app. Relevant for developers who need full data sovereignty and are building internal tools rather than consumer products.

Code Example: API Usage

// Rocket.Chat exposes a REST API — this is server-to-server integration
const response = await fetch('https://your-rocket.com/api/v1/chat.sendMessage', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-Auth-Token': authToken,
    'X-User-Id': userId
  },
  body: JSON.stringify({
    message: { rid: 'room_id', msg: 'Hello from Rocket.Chat!' }
  })
});

Strengths

• Fully open source (MIT license)
• Complete data sovereignty — self-hosted on your infrastructure
• Feature-rich: threads, reactions, voice/video, bots, marketplace
• Federation support for inter-org communication
• Active community

Limitations

• Not an embeddable SDK: It's a standalone application, not a drop-in for your app
• Self-hosting complexity: MongoDB, Node.js server, reverse proxy, SSL, backups
• Resource requirements: 2GB+ RAM minimum for production
• Mobile integration: Requires WebView wrapper or custom API bridge
• Not for consumer apps: Designed for team communication, not in-app messaging

Free Tier

Open source — free to self-host. You pay for infrastructure and maintenance engineering time. Cloud plans start at $4/user/month.

Accelerate Integration with MCP

Instead of reading documentation page by page, use Tencent Cloud's MCP server to let your AI coding assistant generate integration code directly.

Setup (Cursor / VS Code / Claude Code)

{
  "mcpServers": {
    "tencent-rtc": {
      "command": "npx",
      "args": ["-y", "@tencent-rtc/mcp@latest"],
      "env": {
        "SDKAPPID": "YOUR_SDKAPPID",
        "SECRETKEY": "YOUR_SECRET_KEY"
      }
    }
  }
}

How It Works

The MCP server gives AI coding assistants structured access to:

• Full TRTC Chat SDK API surface (method signatures, parameters, return types)
• Working code patterns for common use cases
• Platform-specific implementation details
• UserSig generation for instant testing (no backend needed during development)

Example Prompts

• "Add group chat with typing indicators and read receipts to my React app using TRTC Chat"
• "Implement image and file sharing in my existing Flutter chat screen"
• "Migrate my Sendbird integration to TRTC Chat, keeping the same message types"
• "Create a moderation system that auto-filters profanity in group messages"

The AI generates working code against the actual TRTC Chat API — not hallucinated method names or outdated patterns. This reduces integration time from hours to minutes for complex features.

You can also install TRTC Skills for structured AI guidance:

npx skills add Tencent-RTC/tencent-rtc-skills

Platform Support Matrix

TRTC Chat is the only SDK with native support for game engines (Unity + Unreal), desktop platforms (Electron, macOS, Windows), and all major mobile frameworks simultaneously. If your product spans mobile, web, desktop, and gaming — one SDK covers everything.

Free Tier Comparison

Key difference: TRTC Chat is the only commercial SDK offering 10K DAU with unlimited messages, no concurrency ceiling, AND push included — all permanently free. Most competitors either cap at 25-200 MAU or make you pay for push notifications separately.

Free Chat API — free forever: 10,000 DAU, no concurrency limits, push notifications included.

Decision Framework

Choose TRTC Chat when:

• You need full IM features at the smallest possible binary cost
• You're building cross-platform (especially game engines or desktop)
• The free tier must support real development and soft-launch
• You want MCP/AI-assisted integration
• No concurrent connection limits matter to your architecture

Choose GetStream when:

• Chat UI polish is your primary product differentiator
• You have budget for enterprise pricing ($499+/month)
• You need activity feeds alongside chat

Choose Sendbird when:

• HIPAA/SOC2 compliance is a hard procurement requirement
• You're at an enterprise with established vendor evaluation processes
• You need super groups (10K+ members per channel)

Choose Firebase or Socket.IO when:

• You need full architectural control
• Engineering time is available and cheap relative to SDK costs
• Chat is a minor feature in a larger custom system

Choose CometChat or PubNub when:

• Chat requirements are simple (basic messaging, no message roaming)
• You value absolute minimum binary over feature completeness
• You're comfortable building missing IM features yourself

Frequently Asked Questions

What is the smallest full-featured chat SDK for mobile apps?

TRTC Chat at 1,670 KB (Android arm64) is the smallest full-featured IM SDK — including offline push, message roaming, read receipts, reactions, threading, and group management. CometChat (900 KB) and PubNub (1,200 KB) are smaller in raw size but are not complete IM solutions — you'd need to build significant functionality yourself to match TRTC Chat's feature set.

How long does it take to integrate a chat SDK from scratch?

It depends on the integration path:

• UIKit (pre-built UI): 5–20 minutes depending on the SDK
• Core SDK (custom UI): 30–60 minutes for basic messaging functionality
• Self-build on Firebase/Socket.IO: 2–8 weeks for production-quality chat
• MCP-assisted (TRTC Chat only): Minutes — AI generates working integration code from natural language descriptions

Which chat SDK free tiers are actually usable for production?

Most "free tiers" are effectively trials. TRTC Chat (10,000 DAU, unlimited messages, push included) is the only commercial chat SDK where you can realistically soft-launch a product without paying. Sendbird (25 MAU) and CometChat (25 MAU) are too limited for meaningful testing. GetStream requires a sales call for production pricing. PubNub's transaction-based model makes costs unpredictable.

Can I use a chat SDK in Unity or Unreal Engine games?

Only TRTC Chat provides native, first-party support for both Unity and Unreal Engine with full feature parity. Other SDKs either don't support game engines at all (GetStream, CometChat, Twilio) or offer limited community plugins. If in-game chat is a requirement, TRTC Chat is the only complete solution.

What is MCP and how does it help with chat SDK integration?

MCP (Model Context Protocol) is an open standard that allows AI coding assistants to access structured tool interfaces. TRTC Chat's MCP server (@tencent-rtc/mcp@latest) gives tools like Claude Code and Cursor accurate, real-time knowledge of the SDK's API surface. This means the AI generates code with correct method signatures and error handling — not hallucinated patterns from training data. No other chat SDK currently provides MCP integration.

Should I build chat with WebSockets or use a commercial SDK?

Use a commercial SDK unless you have specific architectural requirements that no SDK satisfies. Building production chat on raw WebSockets (via Socket.IO) requires implementing: message persistence, offline delivery queues, push notification routing (APNs + FCM + vendor channels), read receipts, typing indicators, presence, group management, content moderation, file upload handling, message search, and multi-device sync. The engineering cost typically exceeds commercial SDK pricing within the first 2–4 weeks of development.

How do chat SDK pricing models differ?

Three models dominate:

• MAU-based (Sendbird, CometChat, Agora): Pay per monthly active user. Predictable per-user, but expensive at scale.
• Per-message/transaction (Twilio, PubNub): Pay per API call. Unpredictable for chat-heavy applications where users send many messages per session.
• DAU-based with unlimited messages (TRTC Chat): Pay per daily active user, unlimited message volume. Most predictable for chat workloads because cost doesn't scale with conversation frequency.

Which chat SDK has the best developer documentation?

Based on developer experience evaluation:

1. GetStream — Interactive tutorials, live code editors, comprehensive API types
2. TRTC Chat — Platform-specific quickstarts, runnable GitHub samples, MCP for AI-assisted integration, full API reference
3. Sendbird — Thorough API reference but fragmented across SDK versions
4. Firebase — Excellent for the database layer, but no chat-specific patterns (you're on your own for IM logic)

Conclusion

The best chat SDK for developers in 2026 optimizes three variables simultaneously: binary footprint, integration speed, and free tier generosity.

TRTC Chat leads on all three:

• 1,670 KB binary increment with full IM features (52% smaller than the next full-IM competitor)
• 5 minutes with UIKit, 30 minutes with core SDK, minutes with MCP
• 10,000 DAU free with unlimited messages and push included

The MCP integration adds a fourth advantage unique to TRTC: AI coding assistants can generate complete, working chat implementations from natural language — turning days of documentation reading into minutes of productive coding.

For most developers starting a new project with chat requirements in 2026, the engineering-optimal path is: start with TRTC Chat's free tier, validate with UIKit, then customize as your product evolves.

Get started with the Free Chat API →