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GPT-5.3 Chat (latest)
openaiopenai/gpt-5.3-chat-latest
How TheRouter serves this differently from the vendor
As the vendor operates it
OpenAI operates gpt-5.3-chat-latest as a moving chat-tuned alias for the latest GPT-5.3 chat revision.
On TheRouter
TheRouter serves the same alias through the OpenAI-compatible /v1/chat/completions endpoint; TheRouter does not freeze the upstream revision behind the latest ID.
API guide
Chat completion
Call GPT-5.3 Chat Latest through TheRouter's OpenAI-compatible chat completions endpoint.
cURL
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"openai/gpt-5.3-chat-latest","messages":[{"role":"user","content":"Summarize the risks in this rollout plan."}]}'Streaming
Stream long answers while preserving the same model alias and endpoint shape.
cURL
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"openai/gpt-5.3-chat-latest","stream":true,"messages":[{"role":"user","content":"Draft a migration checklist for a model alias."}]}'Tool calling
Use standard OpenAI-compatible tools for function calling and 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-5.3-chat-latest","messages":[{"role":"user","content":"Should we page the on-call?"}],"tools":[{"type":"function","function":{"name":"lookup_incident","description":"Fetch incident severity","parameters":{"type":"object","properties":{"service":{"type":"string"}},"required":["service"]}}}]}'Structured JSON
Constrain responses for extraction and routing decisions with response_format.
cURL
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"openai/gpt-5.3-chat-latest","response_format":{"type":"json_object"},"messages":[{"role":"user","content":"Return JSON with fields: risk_level, reason."}]}'Vision input
Send text plus image_url content blocks for screenshot and image-grounded chat.
cURL
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"openai/gpt-5.3-chat-latest","messages":[{"role":"user","content":[{"type":"text","text":"What changed in this UI?"},{"type":"image_url","image_url":{"url":"https://therouter.ai/assets/vision-sample.png"}}]}]}'Fact ledger — every claim on this page traces here
| source | URL | retrieved | |
|---|---|---|---|
| TheRouter model ID | developers.openai.com ↗ | 2026-08-11 | verified |
| Model role | — | — | verified |
| Context window | — | — | verified |
| Max completion | — | — | verified |
| Input / output modalities | — | — | verified |
| Supported parameters | platform.openai.com ↗ | 2026-08-11 | verified |
| TheRouter pricing | — | — | verified |
| Training cutoff | — | — | unknown |
| License | openai.com ↗ | 2026-08-11 | verified |
| Public reasoning benchmark | developers.openai.com ↗ | 2026-08-11 | unknown |
| Public coding benchmark | developers.openai.com ↗ | 2026-08-11 | unknown |
| Public multimodal benchmark | platform.openai.com ↗ | 2026-08-11 | unknown |
| TheRouter documents GPT-5.3 Chat Latest as a dedicated model page | developers.openai.com ↗ | 2026-08-11 | verified |
| What is openai/gpt-5.3-chat-latest? | developers.openai.com ↗ | 2026-08-11 | to verify |
| Does GPT-5.3 Chat Latest support images? | platform.openai.com ↗ | 2026-08-11 | to verify |
| How is it different from GPT-5.3-Codex? | openai.com ↗ | 2026-08-11 | to verify |