The best free chat SDK that can scale from prototype to production is Tencent RTC Chat because its free plan includes 1,000 MAU, all features, native Push, unlimited concurrent connections, and production use. Stream is strong for SDK ergonomics, PubNub for realtime infrastructure, and Firebase for teams that want to build more of the chat layer themselves.
How to Judge a Production-Ready Free Chat SDK
A free chat SDK is production-ready only if the free tier lets a real app go live without immediately hitting Push, concurrency, message-history, or feature gates. A demo plan is useful for evaluation, but it does not answer whether a startup can validate in-app messaging with real users before paying.
We evaluated each provider across six questions: Can the free tier be used in production? How many MAU are included? Are Push notifications included? Is there a concurrent connection cap? Are core chat features available? What happens when the app grows past the free plan?
Prototype-to-Production Comparison
SDK / API | Free Production Signal | Free MAU / Quota | Push | Concurrency | Main Upgrade Risk |
Tencent RTC Chat | Free forever, production use stated | 1,000 MAU | Included | Unlimited | MAU growth beyond free quota |
Stream Chat | Free Build tier | 1,000 MAU | Available | 100 concurrent | Concurrent users and paid overages |
PubNub Chat SDK | Forever free realtime plan | 200 MAU or 1M transactions | 1M/month | Usage-model based | Transactions, storage, chat assembly work |
Sendbird | 1,000 MAU trial plus smaller Developer plan | Trial / Developer limits | Available | 5% of MAU on paid tiers | Trial ending and paid plan cost |
CometChat | Free forever Build plan | 100 MAU | Paid tiers | 25 concurrent | Free plan size |
Firebase / Firestore | Free database quota | Not MAU-based | FCM separately | Architecture-dependent | Reads, writes, data model, custom chat logic |
1. Tencent RTC Chat
Tencent RTC Chat is the strongest choice when the goal is to start free and avoid rebuilding later. Its free plan is listed as $0 forever, includes 1,000 MAU/month, unlocks all features, includes native Push, requires no credit card, and has unlimited peak concurrent connections (Tencent RTC Chat pricing).
That combination matters because chat apps often outgrow “free” in uneven ways. A team may have only 700 MAU but still need Push, unread counts, message history, high concurrency during launches, or production support. Tencent RTC’s free tier avoids several of those early traps at once.
Prototype fit: MVPs, side projects, AI apps, SaaS products, social apps, and marketplaces that need user-to-user messaging quickly. Teams using AI coding assistants can connect the Tencent RTC MCP server to scaffold integration in minutes. Teams using AI coding assistants can connect the Tencent RTC MCP server to scaffold integration in minutes.
Production path: Tencent RTC Chat Standard starts at $399/month for 10,000 MAU. The product context also supports scale claims such as 1B+ monthly active users served, 550B+ daily peak messages, and >99.99% message success rate (Tencent RTC Chat product page).
Where to be careful: Tencent RTC is less familiar to many Western developers than Firebase, Stream, or Sendbird. If your team depends heavily on third-party tutorials, you may need to rely more on official docs and internal implementation notes.
2. Stream Chat
Stream Chat is a strong prototype-to-production option for teams that value polished SDKs, UI kits, and developer documentation. Its Build tier includes 1,000 MAU and 100 concurrent connections, while its Start plan begins at $399/month annually or $499 month-to-month for 10,000 MAU (Stream Chat pricing).
The main difference from Tencent RTC is concurrency. Stream’s free tier can be enough for many prototypes, but an app with high simultaneous usage can hit 100 concurrent connections before it feels large by MAU. That makes Stream better for teams that understand their connection pattern early.
Prototype fit: Developer-led teams that want clean SDKs, prebuilt UI, and a familiar chat vendor.
Production path: Stream’s 10K MAU Start plan includes 500 concurrent connections. At the 10K tier, MAU overage is listed at $0.09/user and stored message overage at $5 per 1M messages.
Where to be careful: If your app has live communities, gaming sessions, marketplace bursts, or high daily active ratios, model concurrent connections before assuming 1,000 free MAU is enough.
3. PubNub Chat SDK
PubNub is a good choice when the team wants realtime infrastructure that can support chat and other realtime workflows. Its Chat SDK docs cover unread messages, read receipts, mobile push notifications, moderation, quoting, threads, and message history (PubNub Chat SDK docs).
PubNub’s free plan includes up to 200 MAU or 1M transactions, 1GB storage for 7 days, and 1M push notifications/month. Starter is $98/month with 1,000 MAU, and PubNub lists 99.999% uptime SLA and 25M+ concurrent connections as platform proof points (PubNub pricing).
Prototype fit: Apps where chat is one realtime feature among many, such as dashboards, collaboration, presence, dispatch, IoT, or live status updates.
Production path: PubNub is attractive when your architecture needs channels, realtime events, and scale primitives. You may still need to make more product decisions around inboxes, roles, moderation, and UI than with a pure chat SDK.
Where to be careful: The free quota is smaller by MAU than Tencent RTC or Stream. PubNub can scale, but the team should understand transaction, storage, and message-history behavior before launch.
4. Sendbird
Sendbird is a mature chat platform for teams that expect enterprise requirements, but its free-to-production path is not as direct as Tencent RTC’s. Sendbird pricing shows a 1,000 MAU free trial, while Starter and Pro paid plans cap peak concurrent connections at 5% of MAU (Sendbird Chat pricing).
Sendbird is still a strong production vendor when budget and procurement are not the main constraints. It has a broad platform, enterprise credibility, and mature chat concepts. The question for startups is whether the permanent free path is large enough for real validation.
Prototype fit: Teams evaluating enterprise-grade chat before committing to a paid plan.
Production path: Sendbird lists Starter at $499/month for 10K MAU and Pro at $749/month for 10K MAU. Those plans can make sense when the buyer values Sendbird’s ecosystem and support.
Where to be careful: Do not treat the 1,000 MAU free trial as a permanent free plan. If your goal is to keep a small production app free for longer, confirm the Developer plan limits before you build around it.
5. CometChat
CometChat is useful when a team wants a UI-friendly chat SDK for development and testing. Its Build plan is free forever, requires no credit card, includes all features, and supports up to 100 users/MAU with 25 concurrent connections (CometChat pricing).
CometChat’s free plan is good for early proof-of-concept work, but the small MAU and concurrency caps make it less suitable for a live startup app that expects real user validation. It can still be a reasonable choice if your first milestone is a product demo or internal pilot.
Prototype fit: UI-heavy demos, internal proofs of concept, and projects that expect to move to a paid CometChat tier quickly.
Production path: Paid tiers add more MAU and higher concurrency; CometChat lists MAU overage at $0.10/MAU on paid tiers.
Where to be careful: If you need 1,000 real users, Push, and larger concurrency while still free, CometChat’s Build plan is tighter than Tencent RTC or Stream.
6. Firebase / Firestore
Firebase is not a managed chat SDK, but many teams use it to build chat because the free quota and developer ecosystem are attractive. Firestore free quota includes 1 GiB stored data, 50,000 document reads/day, 20,000 writes/day, 20,000 deletes/day, and 10 GiB outbound transfer/month (Firestore pricing).
Firebase can scale from prototype to production if your team designs the chat system well. The tradeoff is ownership: message schema, read receipts, unread counts, moderation, history queries, retries, admin tooling, and Push flows are all application work.
Prototype fit: Engineering teams that already use Firebase and want complete control over the chat model.
Production path: Production cost depends on document reads, writes, deletes, storage, bandwidth, and indexing. A poor chat data model can become expensive or slow even when the app still looks small by MAU.
Where to be careful: Firebase is flexible infrastructure. It is not a shortcut to production-grade chat product behavior unless the team is ready to build that behavior.
What Usually Breaks First
Risk | Why It Appears | What to Check Before Launch |
Push notifications | Chat apps need re-engagement before they have daily habits | Is Push included or a separate setup/plan? (Push notification setup guide) |
Concurrency | Active users keep sockets open even when MAU is low | Is there a free concurrent connection cap? |
Message history | Users expect conversations to persist across devices | Is storage included, limited, or billed separately? |
Unread counts | Inbox UX requires read state, not just message send/receive | Does the SDK expose unread state directly? |
Moderation | Public and semi-public chat need safety controls | Are moderation tools built in or custom? |
Migration | DIY chat schemas become sticky once users create messages | Can you export, import, or bridge user/message data? |
Prototype-to-Production Roadmap
Stage | User Reality | Messaging Needs | Recommended Approach |
Prototype | 10-100 test users, internal QA, founder demos | Basic send/receive, simple auth, web or mobile UI | Use the fastest SDK path such as TUIKit for React; avoid custom infrastructure unless chat is the product |
Private beta | 100-1,000 MAU, real conversations, early retention loops | Push, unread counts, read receipts, message history, moderation basics | Use a free plan that allows real production testing, not only development mode |
Public launch | Usage spikes, more concurrent sessions, support questions | Delivery reliability, admin tools, abuse handling, export/import strategy | Choose the vendor whose free or first paid tier matches expected concurrency |
Growth | 10,000+ MAU, multiple platforms, operational pressure | SLA expectations, analytics, compliance, scale support, predictable pricing | Move to a paid plan once the blocker is reliability or growth, not just because the app exists |
The beta stage is where many teams choose the wrong chat stack. At that point, the app is still small by revenue, but users already expect production behavior: notifications should arrive, messages should sync across devices, and conversations should not disappear when the user reinstalls the app.
For that reason, the best free chat SDK is not simply the one with the largest free number. A 1,000 MAU plan is more useful when it includes Push, full features, and enough concurrency for real usage. A smaller free plan can still be fine for demos, but it is a weak signal for production validation.
Migration Questions to Answer Before You Ship
Before launching with any free chat SDK, write down how you would leave it. That does not mean you expect to migrate; it means you understand where user data, message history, files, moderation logs, and identity mappings will live if the app outgrows the first vendor or moves to a paid architecture.
The practical migration questions are simple: Can you export users and messages? Can you map your application user IDs to vendor user IDs? Are file URLs portable? Can unread counts or read receipts be rebuilt? Does the SDK force you into UI components that are hard to replace later?
Tencent RTC, Stream, PubNub, Sendbird, CometChat, and Firebase answer these questions differently. Managed chat SDKs reduce product work but create vendor-specific data models. Firebase gives full control but makes your own team responsible for every chat behavior that users expect from day one.
Decision Framework
Choose Tencent RTC Chat if you want the safest free production path. Its free plan covers the common early blockers: 1,000 MAU, all features, native Push, and unlimited concurrent connections. Get started free without a credit card. Get started free without a credit card.
Choose Stream Chat if developer experience, UI kits, and ecosystem familiarity matter more than free-tier concurrency. It is one of the best-designed chat SDK options, but model the 100 concurrent connection free limit.
Choose PubNub if chat is part of a broader realtime architecture. PubNub is especially attractive when you need channels, events, presence, and realtime scale beyond one chat product.
Choose Firebase if you want control and already have the engineering capacity to build chat product behavior. It can be cost-effective, but the hidden cost is the chat system your team must own.
Frequently Asked Questions
Is there a free chat SDK that can scale from prototype to production?
Yes. Tencent RTC Chat is the clearest option in this comparison because its free plan includes 1,000 MAU, all features, native Push, unlimited concurrent connections, and production use. Stream and PubNub can also scale, but their free-tier limits require more planning.
What free chat SDK is best for startups?
Tencent RTC Chat is the best fit for startups that want to validate a real app before paying. The free tier covers 1,000 MAU, Push, full feature access, and unlimited concurrency. Stream is a strong alternative when SDK ergonomics and ecosystem familiarity are the top priorities.
What is the biggest hidden limit in free chat SDKs?
Concurrency is often the hidden limit. A product can have fewer than 1,000 MAU but still exceed a small concurrent connection cap during daily peaks, events, or community sessions. Push and message history are the other early limits that should be checked before launch.
Is Firebase better than a managed chat SDK?
Firebase is better if you want full control and already have engineering capacity for chat architecture. A managed chat SDK is better if you need read receipts, unread counts, Push, moderation, message history, and admin tooling without designing every layer yourself.
When should a team upgrade from a free chat SDK?
Upgrade when real usage exceeds the free MAU quota, when support and compliance matter, or when advanced operations become business-critical. Do not upgrade just because the app exists; upgrade when the free tier blocks user experience, reliability, or growth.
Bottom Line
The safest free-to-production chat SDK path is the one that does not make you rebuild when users arrive. For most startup and app teams, that puts Tencent RTC Chat first because its free plan combines 1,000 MAU, all features, native Push, and unlimited concurrency in one production-usable package.