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Add the Docs MCP to your AI coding tool to get help building with Respan. No API key needed.
{
  "mcpServers": {
    "respan-docs": {
      "url": "https://respan.ai/docs/mcp"
    }
  }
}

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What is Langfuse?

Langfuse is an open-source LLM observability platform. The Respan instrumentor patches Langfuse’s OTLP exporter to redirect traces to Respan — your existing @observe decorators and langfuse.trace() calls continue to work unchanged.

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Setup

1

Install packages

pip install langfuse respan-instrumentation-langfuse
2

Set environment variables

export RESPAN_API_KEY="YOUR_RESPAN_API_KEY"
export LANGFUSE_PUBLIC_KEY="YOUR_LANGFUSE_PUBLIC_KEY"
export LANGFUSE_SECRET_KEY="YOUR_LANGFUSE_SECRET_KEY"
3

Instrument before importing Langfuse

LangfuseInstrumentor().instrument() must be called before importing langfuse. The instrumentor patches the OTLP exporter at import time.
import os
from respan_instrumentation_langfuse import LangfuseInstrumentor

# Instrument BEFORE importing langfuse
LangfuseInstrumentor().instrument()

# Now import and use langfuse normally
from langfuse.decorators import observe
from openai import OpenAI

client = OpenAI()

@observe()
def generate_joke():
    response = client.chat.completions.create(
        model="gpt-4o-mini",
        messages=[{"role": "user", "content": "Tell me a joke about AI"}],
    )
    return response.choices[0].message.content

@observe()
def joke_pipeline():
    joke = generate_joke()
    return joke

result = joke_pipeline()
print(result)
4

View your trace

Open the Traces page to see your Langfuse traces in Respan.
Langfuse trace in Respan

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Configuration

See the Langfuse Instrumentor SDK reference for the full API.