OpenAI Chat Completions — Event Reference

This page documents the streaming frames emitted by POST /api/openai/v1/chat/completions when stream: true.

Frame shape

Each line is an SSE data: JSON object.

Notes:

• Initial chunk includes role: "assistant".
• Text arrives via choices[0].delta.content.
• Tool calling deltas use choices[0].delta.tool_calls[].function.arguments.
• The terminal chunk sets finish_reason to stop, length, or tool_calls.
• When stream_options.include_usage is true, an extra usage-only chunk precedes [DONE].

See also

• OpenAI Chat Completions
• OpenAI Responses
• Generations lookup
• Error codes