Zerouter is a service that provides a single API key for accessing multiple frontier language models, including Claude, GPT, Gemini, Grok, Kimi, Qwen, and DeepSeek. It functions as an alternative to OpenRouter and offers a cheap Claude Code API. The primary function is to route user requests to the specified model without substitution or downgrade, meaning the model named in the request is the model that answers. Users are billed per 1 million tokens at published rates, with charges applied after each request based on actual usage. The service claims pricing up to 93 percent below list price and does not require a subscription. The main features include a unified API key that is checked for balance and concurrency before a request is routed. Users can manage multiple keys and top up their balance through a console dashboard. The service logs each call, detailing input, cache, and output tokens at the public rate. For integration, users only need to change the base URL and API key in their client applications, such as Claude Code, Codex CLI, or Cursor, by pointing ANTHROPIC_BASE_URL or the OpenAI base_url to api.zerouter.ai. The client, prompts, and tools remain unchanged. Typical use cases involve developers and teams who need to access a variety of large language models from a single endpoint without managing multiple subscriptions or API keys. The workflow consists of signing in to the console, topping up a balance, generating an API key, and configuring the client application to use the Zerouter base URL. The service also includes an invite feature for sharing access and earning balance credits. Technical requirements are minimal. Users must have a client application that supports setting a custom base URL for API calls. The service supports models from Anthropic, OpenAI, Google, xAI, and others, with specific model names like claude-opus-5-5, claude-sonnet-5, and gpt-4o listed on the site. The console provides real time usage data, including recent spend and latest requests, allowing users to monitor their activity.