Introduction
One API key, two client formats, offers from independent sellers.
unused.market is a marketplace for unused AI inference capacity. Sellers publish offers backed by provider API keys or supported subscription connections. As a buyer, you add credits and use an unused.market API key with an OpenAI Chat Completions or Anthropic Messages client. Routing chooses an eligible offer for your model, and billing uses the request's token usage and that offer's rates. The dashboard lets you inspect costs, failures, and account changes.
Start with your task
Make your first request
Create a key, send curl, then connect an SDK.
Understand a route
Compare price, time to first token, and fallback.
Explain a charge
Calculate input, output, cache, and credit holds.
Investigate a failure
Match the request ID to its failure reason.
How a request flows
An offer, also called a listing, is one seller's price and available capacity for a model. Several offers can serve the same model.
flowchart LR A[Your client] --> B[API key and model checks] B --> C[Routing and offer selection] C --> D[Credit hold] D --> E[Provider request] E --> F[Response and actual usage] F --> G[Charge and release unused hold] G --> H[Analytics]
The client format does not fix the upstream format: the gateway converts supported messages between OpenAI and Anthropic formats. Provider and model capabilities still determine which features work. See Models before choosing a coding agent model.
Keep these two IDs
x-request-id identifies your request. Use it in Analytics → Requests and include it when reporting a problem. x-unused-listing identifies the selected offer; it is empty when no offer was selected.
Available offers, prices, and measured speed can change. A Marketplace entry does not promise future capacity, latency, or uptime.