Conclusion
- Free agent APIs are useful for smoke tests, not uncontrolled loops.
- OpenAI compatibility lets you switch base_url, key, and model without rewriting the agent.
- Agents need stricter budgets because retries and tool loops can burn credits quickly.
- The safest production path adds logs, rate limits, and fallback before users depend on the agent.
What to do next
- Pick a no-card or credit-backed provider and create a test key.
- Run one single-turn prompt, then one tool-using agent task with max iterations capped.
- Record cost, latency, rate-limit errors, and whether streaming/tool-call output is compatible.
- Set max tokens, max steps, and daily budget before any scheduled agent run.
- Add a paid fallback or gateway when the prototype becomes user-facing.
Recommended paths
| Provider | Free / credits | Best for |
|---|---|---|
| OpenRouter | Free model routes vary | Fast no-card agent prototype |
| SiliconFlow | Free models/credits vary | China-direct compatible endpoint |
| Qwen | Signup credits vary | Coding and long-context agent tests |
| Zhipu GLM | Signup tokens vary | Domestic GLM agent tests |
| Groq | Developer limits vary | Fast lightweight agent calls |
Global developer checklist
- Confirm whether signup, billing, and API keys work from your country before writing production code.
- Prefer OpenAI-compatible endpoints when you may need to switch models, regions, or providers later.
- Test free credits with a real smoke prompt and record latency, error shape, streaming behavior, and quota burn.
- Keep at least one fallback route for provider outages, model deprecations, and regional access changes.
Production handoff
Turn your free agent test into a stable route
Keep the OpenAI-compatible interface, then add budget caps, logs, and fallback behind one production key.
FAQ
Can I run autonomous agents on free APIs?
Only with strict caps. Free limits are easy to exhaust when agents retry, browse, or call tools repeatedly.
Which free route is best from mainland China?
SiliconFlow, Zhipu, and Qwen are the practical first tests because they are China-friendly and commonly support compatible endpoint patterns.
What should I test besides a hello-world prompt?
Test streaming, tool calls, JSON output, rate-limit headers, context length, and recovery from failed tool results.
When should I stop using the free route?
When real users, scheduled jobs, or customer data are involved. Move to paid billing with logs and fallback.