Cossistant

Cossistant ships a support chat widget as React components you compose, rather than a script tag that injects someone else's interface into your page. The approach is code-first and API-driven, with headless hooks and primitives, real-time messaging, and the backend to run all of it, documented for developers and the AI tools they use.

Two packages carry the client side. The React SDK provides the headless hooks and primitives, and a companion package adds Next.js bindings and utilities. Behind them sits a Turborepo monorepo running on Bun, with Hono and tRPC for the API, Drizzle ORM for the database, Better Auth for sessions, WebSockets for live messages, and Docker running Postgres and Redis locally.

The split between widget and infrastructure shapes what you actually get.

• Headless components: styling and layout stay yours, because the SDK ships behavior rather than a fixed look.
• Real-time messaging: conversations travel over WebSockets instead of polling an endpoint.
• Full backend: the API, database and auth are part of the project, not a hosted dependency you rent.
• Next.js package: a separate module covers the framework-specific bindings and utilities.
• Documentation: a quickstart for adding it to an app and a contributors guide.

The project is licensed AGPL-3.0 for non-commercial use, and commercial deployments need a license from the maintainers. It is part of the Vercel open source program and runs a program of its own for other open source projects. It suits a team that wants support chat in their product without handing the conversation to a third party.