| Signal | Result | Reference |
|---|---|---|
| Tokenizer signature | Not measured | – |
| API surface | No other entry shares this exact contract | api_d55f5d09 |
| Context and output | 400,000 context · 128,000 max output | declared |
| Reasoning contract | Mandatory | declared |
| Serving providers observed | None recorded yet | – |
GPT-5-Codex is a specialized version of GPT-5 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....
Supported parameters
include_reasoningmax_tokensreasoningresponse_formatseedstructured_outputstool_choicetools
defaults: {"temperature":null,"top_p":null,"frequency_penalty":null}
Cite this page as the evidence record for OpenAI: GPT-5 Codex (batch): the URL is stable, measurements are dated, and revisions append to the history above. Method: tokenizer fingerprinting, v1, 50 strings. The raw data behind every figure is on the data page.
