One sentence conclusion
"OpenAI Compatible" usually means that some request formats can be reused, but it does not mean that Chat Completions, Responses API, tool calls, images, videos, and Anthropic Messages are all compatible.
If you encounter "OpenAI SDK can make requests, but the actual business still fails", first useOpenAI Compatible Base URL CheckerCheck the final path before usingModel Quality CheckVerify model declarations, SSE and tool calls and finally pressAPI Error Troubleshooting GuideLocate specific status codes.
API capability matrix
AIFast Link offers only GPT and Claude models. The table describes protocols that must be verified separately; it does not mean every model supports every capability.
| Capabilities | Common uses | Verification key points | You cannot judge based on what |
|---|---|---|---|
| Chat Completions | Dialog, text generation | messages、model, streaming return |
/v1/models success |
| Responses API | Codex, tool tasks, unified response events | Event structure, tool invocation, output analysis | Chat request successful |
| Anthropic Messages | Claude Code, Claude Client | Anthropic path, request header, message structure | OpenAI address available |
| SSE Streaming Output | Display generated content in real time | text/event-stream, proxy buffering, disconnection |
Non-streaming request successful |
| Tool Calls | Agent, function call, workflow | Parameter structure, tool result return, multi-round status | Normal text answer is normal |
AIFast Link does not provide standalone image generation, video, embedding or reranking models. Verify image input for each GPT or Claude model; image input is not image generation.
Recommended verification sequence
1. Verify certification and model list
curl https://www.aifast.link/v1/models \
-H "Authorization: Bearer $AIFAST_API_KEY"2. Verify minimal Chat request
curl https://www.aifast.link/v1/chat/completions \
-H "Authorization: Bearer $AIFAST_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "real model copied from model listID",
"messages": [{"role": "user", "content": "Reply with only OK"}]
}'3. Individually verify the capabilities required by the target client
- Codex: Focus on validating Responses API and tool events.
- Claude Code: Focus on verifying the Anthropic Messages entry and authentication variables.
- Dify: Validates the selected model type, credentials, and workflow nodes.
- OpenWebUI, Chatbox, Cherry Studio: Verify Base URL auto-splicing and model ID.
- Agent: Individually tests tool calls, long tasks, timeouts and failure recovery.
Online Judgment Criteria
Only when all the capabilities actually used by the target business pass, can the access be judged to be suitable for production. It is recommended to save:
- Final request URL and status code.
- response
Content-Type. - Request ID or error text.
- Actual model ID.
- Client version and configuration method.
- Streaming, tool invocation, and timeout test results.