Chat21
Chat21: A self-hosted Firebase chat SDK for teams building basic mobile and web messaging. Ranked #17 of 26 in Chat Api by our editors (7.0/10); pricing: Free plan; best for small teams seeking open-source basic messaging.
At a glance
- Editor score7.0 / 10
- PricingFree plan
- Best forSmall teams seeking open-source basic messaging
- Free planYes
- Paid fromFree
- Group chatYes
- Facts checked24 Sep 2026
Where it wins
- Direct and group chat with offline message history
- Android, iOS, web and Ionic SDK coverage
- Receipts, presence, contacts, push and UI components included
Where it doesn't
- Firebase is the documented backend and integration
- Self-hosted deployment requires backend installation and operation
- AGPLv3 licensing may require a commercial licence for some use cases
Our verdict on Chat21
Chat21 is an open-source SDK for developers embedding real-time messaging in mobile and web applications. It supports Android, iOS and web, with Ionic also included in the documented SDK list. The feature set covers one-to-one conversations, group chat, text, image and binary messages, offline message history, delivery and read receipts, presence status, contact synchronization and search, push notifications, and ready-to-use UI components. Small and mid-market teams that need core chat capabilities without building every messaging layer from scratch are the clearest fit.
The project is described as free and open source, with source code distributed under AGPLv3. The vendor also states that a commercial licence is available. Deployment is self-hosted: teams can install the backend in their own Firebase project, using the provided Firebase cloud functions and backend installation instructions. That approach gives developers control over deployment, but it also makes backend setup and ongoing operation part of the implementation responsibility. Teams wanting a managed service should look for a different deployment model.
Firebase is the documented integration, so Chat21 fits best when that backend is already part of the application architecture. Its SDK and UI coverage span the main mobile and web targets, while the product remains focused on foundational messaging rather than a broad integration ecosystem or advanced automation. Email is the listed support channel. Choose Chat21 when open-source control, self-hosting and essential chat functions matter most; consider alternatives if you need many third-party integrations, managed hosting or a wider feature set beyond basic messaging.
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Chat21 pricing
Chat21 fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| Group chat | Yes |
| Self-hosted option | Yes |
| End-to-end encryption | Not verified |
| Moderation tools | Not verified |
| SDK platforms | Android, iOS, Web, Ionic |
| Group size limit | Not verified |
| Deployment | Self-hosted |
| Platforms | Web, Android, iOS |
| Support | |
| Built for | Small business, Mid-market (editorial estimate) |
| Integrations | 1 integrations: Firebase |
| Pricing | Free plan |
| Website | chat21.org |
| Facts checked | 24 Sep 2026 |
Chat21 integrations
Chat21 lists 1 integrations on its own site.
- Firebase
Alternatives to Chat21
- Twilio ConversationsA developer-focused messaging API spanning chat, SMS, MMS, WhatsApp, and Messenger.9.2
- Sendbird ChatA feature-rich chat API for teams that can accommodate paid plans starting at $349 per month.8.8
- Stream ChatBroad chat features and SDK coverage, with paid plans starting at $399 per month billed annually.8.7
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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