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GPT-5.4 Mini

openaiopenai/gpt-5.4-mini

API guide

Chat completion

GPT-5.4 Mini supports the full chat completions API including tool calls, structured output, streaming, and reasoning effort control.

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4-mini",
    "messages": [
      {"role": "system", "content": "You are a helpful coding assistant."},
      {"role": "user", "content": "Write a Python function to merge two sorted lists."}
    ],
    "reasoning_effort": "medium"
  }'

Streaming

Stream responses token-by-token for real-time UX in coding assistants and chat applications.

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4-mini",
    "messages": [{"role": "user", "content": "Explain recursion in one sentence."}],
    "stream": true
  }'

Tool calling

GPT-5.4 Mini excels at tool-calling workflows β€” 57.7% on MCP Atlas and 93.4% on Ο„2-bench, making it reliable for complex orchestration.

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4-mini",
    "messages": [{"role": "user", "content": "What is the weather in Tokyo?"}],
    "tools": [{
      "type": "function",
      "function": {
        "name": "get_weather",
        "description": "Get current weather for a city",
        "parameters": {
          "type": "object",
          "properties": {
            "city": {"type": "string"},
            "units": {"type": "string", "enum": ["celsius", "fahrenheit"]}
          },
          "required": ["city"]
        }
      }
    }],
    "tool_choice": "auto"
  }'

Vision (image input)

GPT-5.4 Mini accepts image inputs alongside text for multimodal reasoning β€” screenshot analysis, document OCR, UI automation.

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4-mini",
    "messages": [{
      "role": "user",
      "content": [
        {"type": "text", "text": "Describe this image."},
        {"type": "image_url", "image_url": {"url": "https://therouter.ai/assets/vision-sample.png"}}
      ]
    }]
  }'

Reasoning effort

Control how deeply GPT-5.4 Mini thinks before answering. Use low for speed, xhigh for maximum quality on complex coding and reasoning tasks.

cURL
curl https://api.therouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $THEROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.4-mini",
    "messages": [{"role": "user", "content": "Solve this coding problem step by step."}],
    "reasoning_effort": "xhigh"
  }'
Fact ledger β€” every claim on this page traces here
sourceURLretrieved
Release dateopenai.com β†—2026-05-29verified
OpenAI model iddevelopers.openai.com β†—2026-05-29verified
Training cutoffβ€”β€”unknown
Reasoning effort levelsopenai.com β†—2026-05-29verified
Cached input pricingdevelopers.openai.com β†—2026-05-29verified
Availabilityopenai.com β†—2026-05-29verified
Licenseβ€”β€”verified
SWE-bench Proopenai.com β†—2026-05-29verified
Terminal-Bench 2.0openai.com β†—2026-05-29verified
GPQA Diamondopenai.com β†—2026-05-29verified
OSWorld-Verifiedopenai.com β†—2026-05-29verified
Toolathlonopenai.com β†—2026-05-29verified
MCP Atlasopenai.com β†—2026-05-29verified
Ο„2-bench (telecom)openai.com β†—2026-05-29verified
HLE w/ toolopenai.com β†—2026-05-29verified
MMMUPro w/ Pythonopenai.com β†—2026-05-29verified
Graphwalks BFS 0K–128Kopenai.com β†—2026-05-29verified
OpenAI launches GPT-5.4 Mini and Nanoopenai.com β†—2026-05-29verified
How does GPT-5.4 Mini compare to GPT-5.4?openai.com β†—2026-05-29to verify
What reasoning effort levels does GPT-5.4 Mini support?openai.com β†—2026-05-29to verify
Is GPT-5.4 Mini available on ChatGPT Free?help.openai.com β†—2026-05-29to verify
Can I use GPT-5.4 Mini in Codex?openai.com β†—2026-05-29to verify
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