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

# Introduction

> Complete API reference for fiddler-otel-js

[![npm](https://img.shields.io/npm/v/@fiddler-ai/otel)](https://www.npmjs.com/package/@fiddler-ai/otel)

## Overview

The `@fiddler-ai/otel` package provides OpenTelemetry instrumentation for
Fiddler AI observability. Use it to automatically capture LLM traces,
conversation context, and span attributes from your TypeScript applications.

```bash theme={null}
npm install @fiddler-ai/otel
```

```typescript theme={null}
import { FiddlerClient } from '@fiddler-ai/otel';
```

## Components

### Client

Client initialization. `FiddlerClient` creates an isolated OpenTelemetry tracer provider that exports traces to Fiddler over OTLP HTTP without registering globally, so it does not interfere with other instrumentation in the same process.

* [FiddlerClient](/sdk-api/otel-js/fiddler-client)

### Internal

Configuration and attribute constants. `FiddlerClientConfig` is the client's options object; `SpanAttributes` and `SpanType` enumerate the attribute keys and span-type values Fiddler recognizes.

* [FiddlerClientConfig](/sdk-api/otel-js/fiddler-client-config)
* [SpanAttributes](/sdk-api/otel-js/span-attributes)
* [SpanType](/sdk-api/otel-js/span-type)

### Spans

Manual span helpers. `FiddlerAgentSpan`, `FiddlerGenerationSpan`, and `FiddlerToolSpan` carry semantic conventions for agent steps, LLM calls, and tool invocations; `FiddlerSpan` is the base, with `StartSpanOptions` and `TokenUsage` as supporting types.

* [FiddlerAgentSpan](/sdk-api/otel-js/fiddler-agent-span)
* [FiddlerGenerationSpan](/sdk-api/otel-js/fiddler-generation-span)
* [FiddlerSpan](/sdk-api/otel-js/fiddler-span)
* [FiddlerToolSpan](/sdk-api/otel-js/fiddler-tool-span)
* [StartSpanOptions](/sdk-api/otel-js/start-span-options)
* [TokenUsage](/sdk-api/otel-js/token-usage)