Review of Thesys
Thesys offers C1, a Generative UI API that transforms LLM responses (OpenAI, Anthropic, Gemini…) into interactive UI components: forms, tables, charts, and dynamic layouts. OpenAI-compatible, C1 plugs into any framework via its React SDK. The C1 Artifacts API enables the generation of complete slides and reports directly inside your applications. A no-code Agent Builder is also available for teams wanting to prototype agents that respond with UI rather than plain text. The freemium model with $10 free credits on sign-up makes onboarding frictionless.
Thesys: L'API qui convertit les sorties de n'importe quel LLM en interfaces utilisateur vivantes et adaptatives.
Best for
- AI agent developers wanting UI-based responses
- SaaS startups integrating LLMs into their products
- Teams building adaptive AI dashboards
- Builders looking to go beyond text-based chatbots
Not ideal for
- Non-developers without API or coding skills
- Projects that don't require dynamic interfaces
- SMBs without dedicated technical resources
- Simple use cases needing plain text responses only
Pros & cons
- ✅ Generative UI: transforms LLM outputs into interactive UI components
- ✅ OpenAI-compatible endpoint, integrates in just a few lines of code
- ✅ Works with all major LLMs including OpenAI, Anthropic, and Gemini
- ✅ C1 Artifacts API for generating slides and reports in real time
- ✅ Free tier with $10 credits, no credit card required
- ✅ No-code Agent Builder to create visual AI agents without coding
- ⚠️ Tool aimed at developers, not accessible to non-technical users
- ⚠️ Documentation still maturing with limited examples for advanced cases
- ⚠️ Usage-based billing can become costly at high volume
- ⚠️ Interface and resources available in English only
Our verdict
Thesys fills an important gap in the AI agent ecosystem: the ability to respond with a dynamic user interface rather than plain text. This approach, called Generative UI, represents a natural evolution of chatbots and AI assistants, which can now present data and results as interactive tables, charts, or forms. Thesys's main strength is its OpenAI compatibility: any existing application using the OpenAI API can migrate to C1 with minimal modifications. The React SDK makes it easy to render generated components on the client side. The C1 Artifacts API adds another dimension by enabling the creation of structured documents — slides, reports — in real time directly within applications. The pricing model is particularly attractive for startups: $10 free credits to get started, then pay-as-you-go. The first 100 artifact pages per month are free. This freemium-to-PAYG positioning fits growing projects well. Thesys is primarily aimed at developers building next-generation AI agents, internal tools, or SaaS products that want to go beyond the limitations of text-only chatbots.
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FAQ
What is Generative UI?
Generative UI is an approach where AI generates interface components — tables, charts, forms — in response to queries, rather than plain text responses.
Is Thesys free?
Yes, Thesys offers $10 in free credits with no credit card required. Usage-based billing starts once credits are used up.
Is Thesys compatible with Anthropic models?
Yes, C1 works with all major LLMs including Anthropic Claude, OpenAI GPT, Google Gemini, and others.
What is the C1 Artifacts API?
The C1 Artifacts API lets you generate slides, reports, and structured documents in real time, directly inside your applications.
Can Thesys be used without coding?
A no-code Agent Builder is available for prototyping, but full C1 API integration requires developer skills.