OpenRouter is the quickest way to try many LLMs
behind one API — and its :free model variants make that genuinely $0. Here’s the
whole setup, including the limits that trip people up.
Step 1 — create an account and an API key
Sign up at openrouter.ai and generate an API key — OpenRouter says its Free plan “works without a payment method”. The API is
OpenAI-compatible, so most existing SDKs work by changing the base URL to
https://openrouter.ai/api/v1 and setting your key.
Step 2 — pick a ‘:free’ model
Free variants have model IDs ending in :free. Browse the models page filtered to
zero price (openrouter.ai/models?max_price=0) and copy the exact ID. Two things to
expect from the catalogue: it’s rotating — models come and go — and free
variants may be slower or more contended than their paid twins. Build with a
fallback model ID rather than hard-coding one.
Step 3 — know your limits before you hit them
The verified numbers from OpenRouter’s pricing page:
- 20 requests per minute on free variants;
- 50 free-model requests per day if you’ve purchased less than $10 in credits;
- 1,000 free-model requests per day once you’ve purchased at least $10 — a one-time lifetime threshold, not a recurring fee.
That $10 unlock is the best value jump in the free-LLM world: a single top-up multiplies your daily free allowance 20x, and the credits you bought remain spendable on paid models.
Step 4 — handle errors like the quota is precious
OpenRouter states that “Failed attempts count toward that daily cap”. Practical consequences: use
exponential backoff on 429s, don’t retry non-retryable errors, and consider
checking your remaining allowance programmatically via OpenRouter’s key endpoint
(GET /api/v1/key) instead of discovering the limit by burning it.
Step 5 — pair it with other free tiers
OpenRouter’s 50/day is a variety buffet, not a volume plan. For heavier free usage, route bulk traffic to Groq or Cloudflare Workers AI and keep OpenRouter for model experimentation — their quotas are independent. The free LLM routers page tracks the current options, and the rate-limits guide covers staying under every provider’s caps.