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

# OpenAI Instrumentation

> Instrument OpenAI API calls with the Go SDK to trace LLM interactions, measure performance, and support agent evaluation pipelines.

LangWatch provides automatic instrumentation for the official `openai-go` client library through a dedicated middleware that captures detailed information about your OpenAI API calls.

## Installation

```bash theme={null}
go get github.com/langwatch/langwatch/sdk-go github.com/openai/openai-go
```

## Usage

<Info>
  Set `LANGWATCH_API_KEY` and `OPENAI_API_KEY` environment variables before running.
</Info>

```go theme={null}
package main

import (
	"context"
	"log"
	"os"

	langwatch "github.com/langwatch/langwatch/sdk-go"
	otelopenai "github.com/langwatch/langwatch/sdk-go/instrumentation/openai"
	"github.com/openai/openai-go"
	oaioption "github.com/openai/openai-go/option"
	"go.opentelemetry.io/otel"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

func main() {
	ctx := context.Background()

	// Set up LangWatch exporter
	exporter, err := langwatch.NewDefaultExporter(ctx)
	if err != nil {
		log.Fatalf("failed to create exporter: %v", err)
	}
	tp := sdktrace.NewTracerProvider(sdktrace.WithBatcher(exporter))
	otel.SetTracerProvider(tp)
	defer tp.Shutdown(ctx) // Critical: ensures traces are flushed

	// Create OpenAI client with LangWatch middleware
	client := openai.NewClient(
		oaioption.WithAPIKey(os.Getenv("OPENAI_API_KEY")),
		oaioption.WithMiddleware(otelopenai.Middleware("my-app",
			otelopenai.WithCaptureInput(),
			otelopenai.WithCaptureOutput(),
		)),
	)

	response, err := client.Chat.Completions.New(ctx, openai.ChatCompletionNewParams{
		Model: openai.ChatModelGPT5,
		Messages: []openai.ChatCompletionMessageParamUnion{
			openai.SystemMessage("You are a helpful assistant."),
			openai.UserMessage("Hello, OpenAI!"),
		},
	})
	if err != nil {
		log.Fatalf("Chat completion failed: %v", err)
	}

	log.Printf("Response: %s", response.Choices[0].Message.Content)
}
```

The middleware automatically captures request/response content, token usage, and model information. Streaming responses are fully supported and automatically accumulated.

<Warning>
  The `defer tp.Shutdown(ctx)` call is essential. Without it, traces buffered in memory will be lost when your application exits.
</Warning>

## Related

* [Capturing RAG](/integration/python/tutorials/capturing-rag) - Learn how to capture RAG data from retrievers and tools
* [Capturing Metadata and Attributes](/integration/python/tutorials/capturing-metadata) - Add custom metadata and attributes to your traces and spans
* [Capturing Evaluations & Guardrails](/integration/python/tutorials/capturing-evaluations-guardrails) - Log evaluations and implement guardrails in your OpenAI applications