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OpenAI · Language model

o3 Pro

openai/o3-pro
  • Language
Released Jun 10, 2025

The o-series of models are trained with reinforcement learning to think before they answer and perform complex reasoning. The o3-pro model uses more compute to think harder and provide consistently...

Specifications

Context window
200,000 tokens
Max output
100,000 tokens
Input
text, file, image
Output
text
Reasoning
supported
Tokenizer
GPT
Knowledge cutoff
2024-06-30
Moderation
provider-moderated

Supported parameters

Accepted by the model and forwarded as-is by the gateway.

  • max_tokens
  • reasoning
  • response_format
  • seed
  • structured_outputs
  • tool_choice
  • tools

Use it

POST /api/v1/chat/completions · MCP chat · full reference

curl https://omnirail.org/api/v1/chat/completions \
  -H "Authorization: Bearer $OMNIRAIL_KEY" -H "Content-Type: application/json" \
  -d '{"model":"openai/o3-pro","messages":[{"role":"user","content":"Hello"}],"max_tokens":300}'