> ## Documentation Index
> Fetch the complete documentation index at: https://docs.burn0.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> One import tracks every API call in your stack

# What is burn0?

burn0 is a lightweight cost observability tool for developers. Add one import to your app and instantly see what every API call costs — LLMs, SaaS APIs, and infrastructure.

<CardGroup cols={2}>
  <Card title="Quick Start" icon="rocket" href="/quickstart">
    Get up and running in 2 minutes
  </Card>

  <Card title="50+ Services" icon="grid" href="/reference/supported-services">
    OpenAI, Stripe, Twilio, Supabase, and more
  </Card>

  <Card title="CLI Tools" icon="terminal" href="/cli/overview">
    Terminal-first cost tracking
  </Card>

  <Card title="Dashboard" icon="chart-bar" href="/dashboard/overview">
    Visual cost breakdown in the browser
  </Card>
</CardGroup>

## How it works

```bash theme={null}
npm i @burn0/burn0
```

Add one line to your app's entry file:

```typescript theme={null}
import '@burn0/burn0'
```

That's it. burn0 automatically:

1. **Intercepts** every outbound HTTP/fetch call
2. **Identifies** which service it's calling (OpenAI, Stripe, Twilio, etc.)
3. **Calculates** the cost based on the provider's pricing
4. **Shows** costs in real-time in your terminal

```
  burn0 ▸ $4.32 today (47 calls) ── openai: $3.80 · anthropic: $0.52
```

## Two modes

<Tabs>
  <Tab title="Local Mode (no API key)">
    Everything stays on your machine. Costs shown in terminal and stored in `.burn0/costs.jsonl`. No network calls to burn0.dev.

    ```bash theme={null}
    # Just install and import — no signup needed
    npm i @burn0/burn0
    ```
  </Tab>

  <Tab title="Cloud Mode (with API key)">
    Events sync to the burn0 dashboard for team visibility, historical trends, and alerts.

    ```bash theme={null}
    # Get a free API key at burn0.dev
    burn0 init
    ```
  </Tab>
</Tabs>

## What it tracks

burn0 supports **50+ services** across three categories:

| Category             | Examples                                        | Pricing                       |
| -------------------- | ----------------------------------------------- | ----------------------------- |
| **LLM Providers**    | OpenAI, Anthropic, Google Gemini, Mistral, Groq | Per-token (auto-calculated)   |
| **Pay-per-use APIs** | Stripe, Twilio, SendGrid, Resend, Google Maps   | Per-request (auto-calculated) |
| **Infrastructure**   | Vercel, Supabase, AWS, Firebase, Neon           | Monthly plan (you configure)  |

<Card title="See all 50+ supported services →" href="/reference/supported-services" />