Update 20251203:
In fact, even if you top up, the free models have many restrictions, and it’s easy to hit usage limits.
The relevant documentation states the following: 20 requests per minute, which can be easily exceeded.
There are a few rate limits that apply to certain types of requests, regardless of account status:
- Free usage limits: If you’re using a free model variant (with an ID ending in
:free), you can make up to 20 requests per minute. The following per-day limits apply:
- If you have purchased less than 10 credits, you’re limited to 50
:freemodel requests per day.- If you purchase at least 10 credits, your daily limit is increased to 1000
:freemodel requests per day.
- DDoS protection: Cloudflare’s DDoS protection will block requests that dramatically exceed reasonable usage.
API Rate Limits | Configure Usage Limits in OpenRouter | OpenRouter | Documentation
Update 20251020:
OpenRouter is not unlimited free (of course), without recharging, you will quickly reach the free quota (I don’t know the exact amount).
At this point, requests will report errors:
Job exception: {"error":{"message":"Rate limit exceeded: free-models-per-day. Add 10 credits to unlock 1000 free model requests per day","code":429,"metadata":{"headers":{"X-RateLimit-Limit":"50","X-RateLimit-Remaining":"0","X-RateLimit-Reset":"xxxxx"},"provider_name":null}},"user_id":"user_xxxxx"}
If you recharge $10, you can then make 1000 free model requests per day again.
Introduction to OpenRouter
Through OpenRouter, you can use various large models on the market, all with one key.
For details about OpenRouter, see: Essential Tools for Individual Developers: OpenRouter Makes Market Large Models Accessible
Currently, OpenRouter provides the free quota for deepseek v3.1, which is sufficient for daily testing needs.
Introduction to dify
Dify is an AI agent construction tool, allowing you to easily create your own AI agents.
Learn more about dify here: Getting Started with AI Agents: dify Super Fast AI Agent Construction - Zhihu
Using OpenRouter’s free deepseek v3.1 in dify
Open settings in dify
Select model provider, and search for openrouter
Fill in the key obtained from OpenRouter, click here to get it
After configuring, you’ll see a large number of models supported by OpenRouter
But note, among these default models, deepseek v3.1 is paid.
You need to add manually
Copy this model name: deepseek/deepseek-chat-v3.1:free
Use the key you previously applied for.
Keep other settings as default; don’t change if unsure.
Verify
It works normally in dify
Cost in OpenRouter shows 0
Done 
More
OpenRouter provides many free models, such as qwen3, kimi k2, etc., with similar usage processes.
See details: Models: ‘free’ | OpenRouter
There is also a free embedding service available at 免费的embedding服务