Braintrust Exporter

Braintrust is an evaluation and monitoring platform that helps you measure and improve LLM application quality. The Braintrust exporter sends your AI traces to Braintrust, enabling systematic evaluation, scoring, and experimentation.

When to Use BraintrustDirect link to When to Use Braintrust

Braintrust excels at:

Evaluation workflows - Systematic quality measurement
Experiment tracking - Compare model versions and prompts
Dataset management - Curate test cases and golden datasets
Regression testing - Ensure improvements don't break existing functionality
Team collaboration - Share experiments and insights

InstallationDirect link to Installation

npm install @mastra/braintrust

ConfigurationDirect link to Configuration

PrerequisitesDirect link to Prerequisites

Braintrust Account: Sign up at braintrust.dev
Project: Create or select a project for your traces
API Key: Generate in Braintrust Settings → API Keys
Environment Variables: Set your credentials:

.env
BRAINTRUST_API_KEY=sk-xxxxxxxxxxxxxxxx
BRAINTRUST_PROJECT_NAME=my-project  # Optional, defaults to 'mastra-tracing'

Basic SetupDirect link to Basic Setup

src/mastra/index.ts
import { Mastra } from "@mastra/core";
import { BraintrustExporter } from "@mastra/braintrust";

export const mastra = new Mastra({
  observability: {
    configs: {
      braintrust: {
        serviceName: "my-service",
        exporters: [
          new BraintrustExporter({
            apiKey: process.env.BRAINTRUST_API_KEY,
            projectName: process.env.BRAINTRUST_PROJECT_NAME,
          }),
        ],
      },
    },
  },
});

Complete ConfigurationDirect link to Complete Configuration

new BraintrustExporter({
  // Required
  apiKey: process.env.BRAINTRUST_API_KEY!,

  // Optional settings
  projectName: "my-project", // Default: 'mastra-tracing'
  endpoint: "https://api.braintrust.dev", // Custom endpoint if needed
  logLevel: "info", // Diagnostic logging: debug | info | warn | error
});