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GPT-5 Nano
openaiopenai/gpt-5-nano
API guide
Chat completion
GPT-5 Nano is called via the standard chat completions endpoint through TheRouter, exactly like any OpenAI-compatible model. All GPT-5 parameters are supported.
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-nano",
"messages": [
{"role": "user", "content": "Classify this text as positive, negative, or neutral: \"The service was okay but nothing special.\""}
],
"reasoning_effort": "minimal",
"response_format": { "type": "json_object" }
}'Streaming
GPT-5 Nano supports streaming for real-time token-by-token output. Combined with minimal reasoning effort, this gives near-instant start-of-response for classification and summary tasks.
cURL
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-H "Accept: text/event-stream" \
-d '{
"model": "openai/gpt-5-nano",
"messages": [
{"role": "user", "content": "Summarize this article in three bullet points: <article text>"}
],
"reasoning_effort": "low",
"stream": true
}'Reasoning effort
GPT-5 Nano supports the full reasoning_effort spectrum: minimal for instant classification, low for balanced extraction tasks, medium as the default, and high for deeper analysis on longer inputs.
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-nano",
"messages": [
{"role": "user", "content": "Extract all entities, dates, and monetary values from this invoice."}
],
"reasoning_effort": "low",
"response_format": { "type": "json_object" }
}'Tool calling
GPT-5 Nano supports parallel tool calls and custom_tools with grammar constraints at the lowest GPT-5 tier pricing.
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-nano",
"messages": [{"role": "user", "content": "What's the weather in Tokyo and what's the current time?"}],
"tools": [{
"type": "function",
"function": {
"name": "get_weather",
"description": "Get current weather for a city",
"parameters": {
"type": "object",
"properties": {
"location": {"type": "string", "description": "City name"}
},
"required": ["location"]
}
}
}],
"parallel_tool_calls": true
}'Fact ledger β every claim on this page traces here
| source | URL | retrieved | |
|---|---|---|---|
| Release date | openai.com β | 2026-05-29 | verified |
| Knowledge cutoff | openrouter.ai β | 2026-05-29 | to verify |
| OpenAI model id | platform.openai.com β | 2026-05-29 | to verify |
| License | β | β | verified |
| SWE-bench Verified | openai.com β | 2026-05-29 | to verify |
| AIME 2025 | openai.com β | 2026-05-29 | to verify |
| MMMU (Multimodal) | openai.com β | 2026-05-29 | to verify |
| GPT-5 family launch β GPT-5, Mini, and Nano | openai.com β | 2026-05-29 | verified |
| How does GPT-5 Nano compare to GPT-5 Mini? | openai.com β | 2026-05-29 | to verify |
| Does GPT-5 Nano support vision? | platform.openai.com β | 2026-05-29 | to verify |
| Is GPT-5 Nano still available after GPT-5.4 Nano was released? | platform.openai.com β | 2026-05-29 | to verify |
| What are the cache-read pricing benefits? | platform.openai.com β | 2026-05-29 | to verify |