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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 Ο2-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
| source | URL | retrieved | |
|---|---|---|---|
| Release date | openai.com β | 2026-05-29 | verified |
| OpenAI model id | developers.openai.com β | 2026-05-29 | verified |
| Training cutoff | β | β | unknown |
| Reasoning effort levels | openai.com β | 2026-05-29 | verified |
| Cached input pricing | developers.openai.com β | 2026-05-29 | verified |
| Availability | openai.com β | 2026-05-29 | verified |
| License | β | β | verified |
| SWE-bench Pro | openai.com β | 2026-05-29 | verified |
| Terminal-Bench 2.0 | openai.com β | 2026-05-29 | verified |
| GPQA Diamond | openai.com β | 2026-05-29 | verified |
| OSWorld-Verified | openai.com β | 2026-05-29 | verified |
| Toolathlon | openai.com β | 2026-05-29 | verified |
| MCP Atlas | openai.com β | 2026-05-29 | verified |
| Ο2-bench (telecom) | openai.com β | 2026-05-29 | verified |
| HLE w/ tool | openai.com β | 2026-05-29 | verified |
| MMMUPro w/ Python | openai.com β | 2026-05-29 | verified |
| Graphwalks BFS 0Kβ128K | openai.com β | 2026-05-29 | verified |
| OpenAI launches GPT-5.4 Mini and Nano | openai.com β | 2026-05-29 | verified |
| How does GPT-5.4 Mini compare to GPT-5.4? | openai.com β | 2026-05-29 | to verify |
| What reasoning effort levels does GPT-5.4 Mini support? | openai.com β | 2026-05-29 | to verify |
| Is GPT-5.4 Mini available on ChatGPT Free? | help.openai.com β | 2026-05-29 | to verify |
| Can I use GPT-5.4 Mini in Codex? | openai.com β | 2026-05-29 | to verify |