OpenRouter vs StepFun API

OpenRouter

Public OpenAPI document, llms.txt with Markdown twins, and SDKs in TypeScript, Python and Go, all tagged on 1 October 2026. No machine payment. USDC top-ups go to a prepaid balance.

StepFun API

StepFun's API serves Step 5 Preview with a 1M-token context, video input, strict JSON Schema output and published per-token prices, documented in Markdown with an llms.txt. The model is a preview with no release date found, there's no free allowance or SLA, and the terms and privacy policy leave room to train on customer data.

OpenRouter

1. Set provider.data_collection: "deny" or provider.zdr: true when the prompt holds anything private
2. Pass a models list so a failed provider falls through to the next one
3. Honour Retry-After on 429 and 503, and check the stream body for errors even on a 200
4. Set max_price so a routed request can't land on an expensive provider
5. Free models allow 50 requests a day until $10 of credit has been bought. Check GET /api/v1/key for what's left

StepFun API

1. Set max_tokens yourself. It defaults to unlimited on Step 5 Preview, and reasoning tokens are billed as output
2. Use response_format with type: json_schema and strict: true when the shape matters. JSON Mode alone isn't schema-checked
3. Back off and retry on 429, 500, 503 and 504. The docs give no Retry-After header or backoff schedule
4. Expect HTTP 451 or finish_reason: content_filter when content fails StepFun's review, and don't retry the same input
5. Use api.stepfun.ai for the international platform. api.stepfun.com is the China platform with yuan pricing