ElevenLabs

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Setup

pnpm add braintrust @elevenlabs/elevenlabs-js

npm install braintrust @elevenlabs/elevenlabs-js

BRAINTRUST_API_KEY=<your-braintrust-api-key>
ELEVENLABS_API_KEY=<your-elevenlabs-api-key>

# For organizations on the EU data plane, use https://api-eu.braintrust.dev
# For self-hosted deployments, use your data plane URL
# BRAINTRUST_API_URL=<your-braintrust-api-url>

​

Auto-instrumentation

import { initLogger } from "braintrust";
import { ElevenLabsClient } from "@elevenlabs/elevenlabs-js";

initLogger({
  projectName: "elevenlabs-example",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = new ElevenLabsClient({
  apiKey: process.env.ELEVENLABS_API_KEY,
});

const audio = await client.textToSpeech.convert(
  "<voice-id>", // Replace with your ElevenLabs voice ID
  {
    text: "Braintrust traces all your AI calls.",
    modelId: "eleven_flash_v2_5",
  },
);

for await (const chunk of audio) {
  // process audio chunk
}

node --import braintrust/hook.mjs trace-elevenlabs-auto.js

​

Manual instrumentation

import { initLogger, wrapElevenLabs } from "braintrust";
import { ElevenLabsClient } from "@elevenlabs/elevenlabs-js";

initLogger({
  projectName: "elevenlabs-example",
  apiKey: process.env.BRAINTRUST_API_KEY,
});

const client = wrapElevenLabs(
  new ElevenLabsClient({
    apiKey: process.env.ELEVENLABS_API_KEY,
  }),
);

const audio = await client.textToSpeech.convert(
  "<voice-id>", // Replace with your ElevenLabs voice ID
  {
    text: "Braintrust traces all your AI calls.",
    modelId: "eleven_flash_v2_5",
  },
);

for await (const chunk of audio) {
  // process audio chunk
}

​

What Braintrust traces

• Text-to-speech spans (elevenlabs.textToSpeech.convert): input text, voice ID, and model as metadata. Generated audio is attached as a Braintrust attachment with content type audio/mpeg.
• Streaming text-to-speech spans (elevenlabs.textToSpeech.stream): same as above, with time_to_first_token captured for the first audio chunk.
• Timestamped text-to-speech spans (elevenlabs.textToSpeech.convertWithTimestamps, elevenlabs.textToSpeech.streamWithTimestamps): same fields as their non-timestamped counterparts, including word-level timing data.
• Transcription spans (elevenlabs.speechToText.convert): audio input and model as metadata. Transcript text is captured as output.
• Errors captured on every call.

​

Resources

• ElevenLabs JavaScript SDK.
• ElevenLabs API reference.