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OpenAI · Language model

GPT-5 Mini

openai/gpt-5-mini
  • Language
Released Aug 7, 2025

GPT-5 Mini is a compact version of GPT-5, designed to handle lighter-weight reasoning tasks. It provides the same instruction-following and safety-tuning benefits as GPT-5, but with reduced latency and cost....

Specifications

Context window
400,000 tokens
Max output
128,000 tokens
Input
text, image, file
Output
text
Reasoning effort
high, medium, low, minimal (always on)
Tokenizer
GPT
Knowledge cutoff
2024-05-31
Moderation
provider-moderated

Supported parameters

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

  • max_completion_tokens
  • max_tokens
  • reasoning
  • reasoning_effort
  • 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/gpt-5-mini","messages":[{"role":"user","content":"Hello"}],"max_tokens":300}'