Join the Beta
The beliefs SDK is in active beta. We're onboarding developers building agents that need to track what they believe, how confident they are, and why things changed across many turns.
Early software, stable core. We ship weekly. Breaking changes are rare and always communicated in advance, with migration help for anyone affected.
Ready to get started? Sign up for the beta → and we'll get you access within 48 hours.
What You Get
- Full SDK access.
beliefspackage with built-in adapters for Vercel AI SDK and Claude Agent SDK. - Founder Studio. The visual workspace for exploring and managing belief states.
- Direct line to the team. Private channel with engineering for support, feedback, and feature requests.
- Early influence. The API surface is not locked. Your feedback shapes what ships in 1.0.
What Beta Means
- The core loop (
before/after, belief extraction, fusion) is stable. It's running in production agents today. - The API surface is still evolving. We communicate breaking changes in advance and help you migrate.
- We ship updates weekly. You'll see things move fast.
- Rough edges exist, and we want to hear about every one of them.
Who This Is For
- Agent builders who need structured state across multi-turn conversations
- Research and analysis teams building decision-support or investigation agents
- Developers who have outgrown simple memory and RAG and want traceable, probabilistic belief tracking
- Anyone curious about giving agents a real world model
Sign Up
Tell us what you're building and we'll get you set up.
You can also reach us directly at devs@thinkn.ai.