Claude Opus 5.5 API free: up to $10 promotional usage
Use the Claude Opus 5.5 API free with up to $10 in promotional API usage through an independent Anthropic-compatible or OpenAI-compatible gateway. Verify the live catalogue, then connect your application.
Get $5 by connecting Telegram and another $5 by joining the LLMsRelay channel. This free access is promotional usage, not cash or unlimited access.
Open the free usage flow- Model ID
- claude-opus-5-5
- Endpoint
- POST /v1/messages
- Authentication
- x-api-key
Availability is key-dependent. Call GET /v1/models after creating a key; the response is the source of truth for your account.
- 1. Create an account and an API key.
- 2. Call GET /v1/models to confirm the model is enabled.
- 3. Send a request to the model endpoint.
curl https://api.llmsrelay.com/v1/messages \
-H "x-api-key: YOUR_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "content-type: application/json" \
-d '{
"model": "claude-opus-5-5",
"max_tokens": 1024,
"messages": [{"role": "user", "content": "Review this architecture"}]
}'Questions about Claude Opus 5.5
Is Claude Opus 5.5 free to use?
LLMsRelay can provide up to $10 in promotional API usage through the reward flow. This is promotional usage, not cash and not unlimited access. Model availability still depends on the API key.
How do I call Claude Opus 5.5?
Use POST /v1/messages with model ID claude-opus-5-5. First call GET /v1/models because the live catalogue is filtered by key group and account settings.
Which tools and SDKs work?
Use the Anthropic-compatible Messages API for Claude models or the OpenAI-compatible Chat Completions API for GPT-6 Astra. Both work with compatible SDKs after changing the base URL and key.