Quick reference for known differences vs the official OpenAI API. Validate against reference pages before production.
Generally compatible
| Area | Notes |
|---|
| Chat Completions | messages, stream, tools / tool_calls |
| Embeddings | model + input |
| Files | Upload, list, delete, download |
| Audio speech | model, input, voice, formats |
| Errors | { error: { message, type, param, code } } |
Catalog and model ids
| Item | RouterBrain | OpenAI |
|---|
| List API | GET /models, OpenRouter-like data[] | OpenAI catalog |
model value | Catalog id (e.g. vendor/model) | gpt-4o, etc. |
| List auth | No key required | Usually required |
Catalog pricing is indicative — billing is in the console.
Gateway-only fields
| Field | Description |
|---|
pdf_preprocess | PDF handling |
extra_body | Merged upstream JSON |
stream_options.include_usage | Usage on streams |
User content parts
| Supported | Notes |
|---|
text, image_url, input_audio, file | file type expects nested file object: file_data + filename |
SDK
For embeddings and similar, use HTTP directly. See Limitations for what the SDK wraps.
Migration
From OpenAI · From OpenRouter