Models & Pricing
C1 is family of API endpoints that use different underlying LLM models. The pricing is based on the model family and the amount of tokens used. Pricing is based on model name irrespective of the kind of endpoint you use. For example, using the embed endpoint withc1/anthropic/claude-sonnet-4/v-* is priced the same as using the visualize
endpoint with the same model.
Generally speaking, a model name is more than just the model of the LLM it uses.
It also includes the version of the model, the set of components available for use in the UI,
and any other metadata.
This guide is called “Models” and not “API Versions” because typically you’d pass
the API version to the model parameter in the request to the LLM compatible
endpoints of C1.
Model Versions & SDK Requirements
Thesys supports all major models — including every model from OpenAI, Anthropic, and Google, as well as the full catalog of models available via OpenRouter. All models use the same model string format:c1/provider/model/v-*
c1prefix: marks the request as a C1 Generative UI requestprovider/model: standard provider/model path (follows the OpenRouter naming convention)v-*: the Thesys API version — see API Changelog for details on each release
Only
v-20251230 is currently supported for OpenRouter models.Model Coverage
OpenAI, Anthropic & Google are accessed through first-party APIs, giving you full compliance coverage, zero data retention guarantees, and rigorous quality assurance. These are the primary recommended providers and the ones we actively test and optimise against. See the Recommended Models section for a curated list. For example, to use Claude Opus 4.6:c1/anthropic/claude-opus-4.6/v-20251230.
All other models are available via OpenRouter — any model in the OpenRouter catalog works with the same c1/provider/model/v-* format. You can configure provider constraints such as ZDR and data residency via the provider parameter in your API request — see OpenRouter Provider Routing. For example, to use Qwen 3.5: c1/qwen/qwen3.5-397b-a17b/v-20251230.
Recommended Models
Embed Endpoint Models
Claude Sonnet 4
Model:
c1/anthropic/claude-sonnet-4/v-20251230Install Dependencies:GPT-5.2
Model:
c1/openai/gpt-5.2/v-20251230Install Dependencies:GPT-5
Model:
c1/openai/gpt-5/v-20251230Install Dependencies:Gemini 3 Pro
Model:
c1/google/gemini-3-pro/v-20251230Install Dependencies:Gemini 3 Flash
Model:
c1/google/gemini-3-flash/v-20251230Install Dependencies:Visualize Endpoint Model
Claude Sonnet 4
Model:
c1/anthropic/claude-sonnet-4/v-20251230Install Dependencies:Artifact Endpoint Model
Artifacts Model
Model:
c1/artifact/v-20260130Install Dependencies:Other Model Versions
Deprecated Models
Deprecated Models
| C1 Model (Latest Version) | genui-sdk | react-ui | react-core |
|---|---|---|---|
c1/anthropic/claude-3.5-sonnet/v-20250709 | ~0.6.27 | ~0.8.14 | ~0.7.6 |
c1/anthropic/claude-3.7-sonnet/v-20250709 | ~0.6.27 | ~0.8.14 | ~0.7.6 |
c1-latest | — | — | — |
c1-202504XX* | — | — | — |
Model Specifications
These specifications apply to all versions of each model family.| C1 Model | LLM | Input Price / M tokens | Cached Input (Read) | Cached Input (Write) | Output Price / M tokens | Context Window | Max Output |
|---|---|---|---|---|---|---|---|
c1/anthropic/claude-sonnet-4 | Sonnet 4 | $3.00 | $0.30 | $3.75 | $15.00 | 200K | 64K |
c1/openai/gpt-5.2 | GPT 5.2 | $1.75 | $0.175 | — | $14.00 | 400K | 128K |
c1/openai/gpt-5 | GPT 5 | $1.25 | $0.125 | — | $10.50 | 400K | 128K |
c1-exp/anthropic/claude-sonnet-4.5 | Sonnet 4.5 | $3.00 | $0.30 | $3.75 | $15.00 | 200K | 64K |
c1-exp/anthropic/claude-haiku-4.5 | Haiku 4.5 | $1.00 | $0.10 | $1.25 | $5.00 | 200K | 64K |
c1-exp/anthropic/claude-3.5-haiku | 3.5 Haiku | $0.80 | $0.80 | $1.00 | $4.00 | 200K | 8192 |
c1-exp/openai/gpt-4.1 | GPT 4.1 | $2.00 | $0.50 | — | $8.00 | 1M | 32K |