/legacy. Everything that used to be at
docs.thesys.dev/<page> is served at docs.thesys.dev/legacy/<page>, and the old URLs
redirect to the OpenUI docs.
Building something new?
OpenUI is the actively developed successor to C1. Start there.
If you already run C1
C1 and its APIs keep working, and these pages keep describing them. Nothing here is being removed — it is just no longer the default entry point.- Setup — install the SDK and call the C1 API
- API reference — endpoints, models, rate limits, errors
- React reference —
C1Component,C1Chat,ThemeProvider - Agent Builder — embed widget and BYOI
- Troubleshooting
Moving to OpenUI
The OpenUI migration guide maps the old component props ontoAgentInterface. For questions specific to your setup,
talk to us or ask in Discord.