OpenRouter

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Setup

pnpm add braintrust @openrouter/sdk

npm install braintrust @openrouter/sdk

OPENROUTER_API_KEY=<your-openrouter-api-key>
BRAINTRUST_API_KEY=<your-braintrust-api-key>

# If you are self-hosting Braintrust, set the URL of your hosted dataplane
# BRAINTRUST_API_URL=<your-braintrust-api-url>

​

Auto-instrumentation

import { initLogger } from "braintrust";
import { OpenRouter } from "@openrouter/sdk";

initLogger({
  projectName: "My Project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = new OpenRouter({ apiKey: process.env.OPENROUTER_API_KEY });

const response = await client.chat.send({
  chatRequest: {
    model: "openai/gpt-5-mini",
    messages: [{ role: "user", content: "What is observability?" }],
  },
});

node --import braintrust/hook.mjs app.js

​

Manual instrumentation

import { initLogger, wrapOpenRouter } from "braintrust";
import { OpenRouter } from "@openrouter/sdk";

initLogger({
  projectName: "My Project",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = wrapOpenRouter(
  new OpenRouter({ apiKey: process.env.OPENROUTER_API_KEY }),
);

const response = await client.chat.send({
  chatRequest: {
    model: "openai/gpt-5-mini",
    messages: [{ role: "user", content: "What is observability?" }],
  },
});

​

What Braintrust traces

• Chat completion spans (openrouter.chat.send), capturing messages as input, request parameters as metadata, and the response choices plus token usage as output. Streaming responses are aggregated (including reasoning and tool calls) and record first-token timing.
• Embedding spans (openrouter.embeddings.generate), capturing input texts as input and the first embedding’s vector length as output.
• Rerank spans (openrouter.rerank.rerank), capturing the query and documents as input, document count and request parameters as metadata, and results as a list of { index, relevance_score } items.
• Response spans (openrouter.beta.responses.send), capturing input and request parameters as metadata and the response output plus token usage as output, including streaming.
• Request metadata (model and provider parsed from the OpenRouter provider/model ID) and token usage metrics (prompt, completion, and total).

​

Resources

• OpenRouter TypeScript SDK
• OpenRouter API reference