C1 by Thesys

About C1 by Thesys

C1 by Thesys is a Generative UI API that lets large language models return interactive user interface elements - charts, forms, cards and dashboards - instead of plain text. It integrates with existing LLMs and frameworks using a minimal setup (advertised as just two lines of code) so responses can include live UI components in real time.

Review

This tool targets developers who want to move beyond text-only model outputs and build richer AI-driven applications faster. In practice, C1 focuses on making model responses directly usable as UI, with features like streaming support, error handling, and the ability to plug in custom React components.

Key Features

• Generative UI outputs: models can return interactive charts, forms, cards and dashboards instead of plain text.
• Minimal setup: an advertised two-line integration and a one-line starter command (npx create-c1-app) to get going quickly.
• Compatibility: works with OpenAI-compatible stacks and most frameworks or MCPs, and supports tool calls to databases, documents and APIs.
• Production-ready behaviors: built-in handling for streaming, error states, configurable actions, callbacks and workflows.
• Extensibility: ability to plug in custom React components with state, logic and validation for bespoke UIs.

Pricing and Value

The launch information highlights free options and a promotional offer to claim 5M free tokens for new users. Detailed commercial pricing and enterprise tiers were not published on the launch page, so teams should consult the official site or sales channels for usage-based or volume pricing. For teams that need to compress UI development time and reduce front-end boilerplate, C1's API approach can offer strong time savings if the integration and token costs align with project budgets.

Pros

• Speeds up development by moving UI generation into the model response flow, reducing hard-coded interfaces.
• Broad compatibility with different LLMs and frameworks makes it flexible for existing stacks.
• Supports streaming, error handling and configurable workflows for real-world application needs.
• Allows custom React components, which is useful for teams that require specific UI behavior or branding.

Cons

• Launch-stage product with relatively few public reviews and case studies, so long-term behavior and edge cases are still being proven.
• Teams without React experience may face a learning curve to fully customize components.
• Commercial pricing details are sparse on the launch page, making total cost estimates harder without contacting the provider.

Overall, C1 by Thesys is best suited for developer teams building AI-native applications that need interactive, data-driven interfaces and want to reduce the time spent wiring up UI elements. It's a practical option for projects where integrating model-driven UI responses and custom React components will cut development effort, but evaluate pricing and maturity against project requirements before committing.

Open 'C1 by Thesys' Website