GPT-5.3 Models Now Available via API

Date: 2026-03-05 Version: OpenClaw 2026.2.26

Contrary to my earlier report, both GPT-5.3 models are now accessible via the OpenAI API with a standard API key. We confirmed this with live calls on March 5, 2026.

What's Available

• gpt-5.3-codex — available via the Responses API. Optimized for agentic coding tasks: writing, debugging, deploying, long-running multi-step work. Powers the Codex app/CLI.
• gpt-5.3-chat-latest — available via the Chat Completions API. General-purpose assistant model for writing, Q&A, and everyday tasks.

TL;DR: Codex = specialized coding agent. Chat Latest = general purpose. If you're building a coding tool, use Codex. For everything else, use chat-latest.

Note: when using gpt-5.3-codex via the Responses API, omit the reasoning parameter — passing reasoning: { effort: "medium" } results in an empty response.

Pricing

OpenAI has not yet published official per-token pricing for the 5.3 models. For reference, GPT-5.2 is priced at $1.75 / 1M input tokens and $14.00 / 1M output tokens — 5.3 pricing is expected to follow in the coming weeks.

curl Examples

gpt-5.3-codex (Responses API):

curl https://api.openai.com/v1/responses \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gpt-5.3-codex",
    "input": "Write a function in Python that reverses a string."
  }'

gpt-5.3-chat-latest (Chat Completions API):

curl https://api.openai.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "gpt-5.3-chat-latest",
    "messages": [{ "role": "user", "content": "Write a function in Python that reverses a string." }]
  }'