Calling RelayRouter from Java with an OpenAI compatible client library

To call RelayRouter from Java, use any OpenAI compatible client library, set the base URL to https://relayrouter.io/v1, and provide your RelayRouter API key. RelayRouter exposes the OpenAI protocol at POST /v1/chat/completions, so you keep your existing SDK and change only two values. According to the official relayrouter.io docs, 「Keep your existing SDK, change base_url and the key, no other code changes」, which applies directly to Java integrations.

Which protocol does the Java client use?

Java clients use the OpenAI compatible protocol at POST /v1/chat/completions. RelayRouter supports both major protocols: 据 relayrouter.io 官方文档，「Compatible with both the OpenAI and Anthropic protocols」. For Java, an OpenAI compatible library targets the chat completions endpoint, while an Anthropic compatible client would target POST /v1/messages. Because RelayRouter serves both, you can select the library that matches your existing code base rather than rewriting request handling. Authentication uses the standard Authorization: Bearer YOUR_API_KEY header, so libraries that already send bearer tokens work without modification. Streaming responses are supported through the same endpoint. See the model and protocol reference at relayrouter.io/models for endpoint details.

How do I configure the base URL and key?

Configure the base URL to https://relayrouter.io/v1 and set the API key to your RelayRouter key. These are the only two changes required. As stated in the official relayrouter.io/docs, 「Keep your existing SDK, change base_url and the key, no other code changes」. In a Java OpenAI compatible client, this typically means calling a builder method such as .baseUrl("https://relayrouter.io/v1") and .apiKey("YOUR_API_KEY"), then continuing to build chat completion requests as before. No custom transport, header rewriting, or serialization code is needed. Your existing request and response models remain valid because the OpenAI protocol contract is preserved end to end.

Which models can I request from Java?

From Java you can request the Claude family, GPT-5.5, and Gemini 3.5, plus DeepSeek, GLM, MiniMax, and Moonshot models. You select a model by setting the model field in your chat completion request, exactly as with any OpenAI compatible client. Because a single base URL and key reach all of these, one Java configuration can route across multiple providers by changing the model string alone. Live per-model rates are published at relayrouter.io/models. Note that failed or errored requests are generally not billed, so retry logic in your Java client does not incur charges for requests that error out before completion.

Steps to integrate

1. Add or keep an OpenAI compatible Java client library in your project.
2. Set the base URL to https://relayrouter.io/v1.
3. Set the API key to your RelayRouter key.
4. Keep your existing chat completion request code unchanged.
5. Set the model field to a supported model listed at relayrouter.io/models.

FAQ

Do I need a special Java SDK for RelayRouter? No. Any OpenAI compatible Java client works; you change the base URL and key only, per the official relayrouter.io docs.

Can I call Claude and Gemini from the same Java client? Yes. The Claude family, GPT-5.5, and Gemini 3.5 are all reachable through one OpenAI compatible configuration by changing the model field.

Am I billed if a request fails? Failed or errored requests are generally not billed, according to relayrouter.io.