Hand it to your AI agent
Copy this prompt into Claude Code, Cursor, Codex or any coding agent. It tells the agent where the docs are and how to use your API key.
Integrate the model `gpt-6-astra` from Half Off Dev into this project through the OpenAI Chat Completions and Responses APIs. - Docs (read first): https://halfoff.dev/docs/models/openai.md - Use the official OpenAI SDK with base URL https://halfoff.dev/v1 (or set OPENAI_BASE_URL=https://halfoff.dev/v1). Endpoints: POST /v1/chat/completions and POST /v1/responses, unchanged from OpenAI. - Model id: `gpt-6-astra`. GET https://halfoff.dev/v1/models lists every model with its price. - Auth: read my API key from the HALFOFF_API_KEY environment variable and send it as `Authorization: Bearer $HALFOFF_API_KEY`. Never print or commit the key. If it is not set, ask me to create one at https://halfoff.dev/app/keys. - Billing is prepaid: every call is charged to my balance, so test with a small request before running anything large. - Every docs page is plain Markdown; the full index is https://halfoff.dev/llms.txt. My task: <describe what you want to build or get>
What a request costs
10,000 input + 1,000 output tokens: $0.075
The same with 9,000 input tokens from the cache: $0.035
Price by channel group
| Channel group | Input | Output | Cache read |
|---|---|---|---|
GPT · Value Pooled capacity | $5.00 | $25.00 | $0.50 |
Call it
Quickstart →OpenAI Chat Completions
curl https://halfoff.dev/v1/chat/completions \
-H "Authorization: Bearer $HALFOFF_API_KEY" \
-H "content-type: application/json" \
-d '{"model": "gpt-6-astra", "messages": [{"role": "user", "content": "Hello"}]}'Frequently asked questions
How much does GPT-6 Astra cost per million tokens?
$5.00 per 1M input tokens and $25.00 per 1M output tokens at the lowest-priced channel group. A request with 10,000 input and 1,000 output tokens costs about $0.075.
Does GPT-6 Astra support prompt caching?
Yes. Cache reads cost $0.50 per 1M tokens, so the same request with 9,000 of its input tokens read from the cache costs about $0.035. Half Off Dev keeps a conversation on the same channel so its cache stays warm.
What is the context window of GPT-6 Astra?
1.05M tokens.
Which API format does GPT-6 Astra use?
OpenAI Chat Completions, OpenAI Responses API. Use the official SDK you already have: change its base URL to Half Off Dev and use your Half Off Dev API key.
Is there a subscription or rate limit?
No subscription: you top up a prepaid balance and pay per token. You can set your own requests-per-minute and concurrency limits on each API key.