Thesys
C1 Claude Sonnet 4
Default
Advanced Claude model with 1M token context and enhanced capabilities
Intelligence
Speed
Price
$3.00 • $15.00
Input
Output

C1 Claude Sonnet 4 is advanced claude model with 1m token context and enhanced capabilities. Learn more in our C1 Claude Sonnet 4 usage guide.

1,000,000 context window
8,192 max output tokens
Aug 2025 knowledge cutoff
Pricing
Pricing is based on the number of tokens used. For tool-specific models, like search and computer use, there's a fee per tool call. See details in the pricing page.
Text tokens
Per 1M tokens
Batch API price
Input
$3.00
Cached input
$0.30
Output
$15.00
Quick comparison
Input
Cached input
Output
C1 Claude Sonnet 4
$3.00
Modalities
Text
Input and output
Image
Input only
Audio
Not supported
Endpoints
Chat Completions
v1/chat/completions
Responses
v1/responses
Batch
v1/batch
Realtime
v1/realtime
Assistants
v1/assistants
Fine-tuning
v1/fine-tuning
Embeddings
v1/embeddings
Image Generation
v1/images/generations
Image Edit
v1/images/edits
Speech Generation
v1/audio/speech
Transcription
v1/audio/transcriptions
Translation
v1/translations
Moderation
v1/moderations
Completions (legacy)
v1/completions
Features
Streaming
Supported
Function calling
Supported
Structured outputs
Not supported
Fine-tuning
Not supported
Distillation
Not supported
Fast response
Not supported
Cost efficient
Not supported
Tools
Tools supported by this model when using the Responses API.
Web search
Supported
Code interpreter
Supported
File search
Not supported
Image generation
Not supported
MCP
Not supported
Snapshots
Snapshots let you lock in a specific version of the model so that performance and behavior remain consistent. Below is a list of all available snapshots and aliases for C1 Claude Sonnet 4.
Thesys
c1-claude-sonnet-4
claude-sonnet-4-20250514
Rate limits
Rate limits ensure fair and reliable access to the API by placing specific caps on requests or tokens used within a given time period. Your usage tier determines how high these limits are set and automatically increases as you send more requests and spend more on the API.
TierRPMTPMBatch queue limit
FreeNot supported
Tier 15040,000200,000
Tier 21000100,000500,000
Tier 32000200,0001,000,000
Tier 44000400,0002,000,000
Tier 54000400,0002,000,000