Langfuse.Core 1.4.1

.NET 8.0

dotnet add package Langfuse.Core --version 1.4.1

NuGet\Install-Package Langfuse.Core -Version 1.4.1

This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.

<PackageReference Include="Langfuse.Core" Version="1.4.1" />

For projects that support PackageReference, copy this XML node into the project file to reference the package.

<PackageVersion Include="Langfuse.Core" Version="1.4.1" />
                    

                            Directory.Packages.props

<PackageReference Include="Langfuse.Core" />
                    

                            Project file

For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.

paket add Langfuse.Core --version 1.4.1

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

#r "nuget: Langfuse.Core, 1.4.1"

#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.

#:package Langfuse.Core@1.4.1

#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.

#addin nuget:?package=Langfuse.Core&version=1.4.1
                    

                            Install as a Cake Addin

#tool nuget:?package=Langfuse.Core&version=1.4.1
                    

                            Install as a Cake Tool

The NuGet Team does not provide support for this client. Please contact its maintainers for support.

Langfuse .NET SDK (Unofficial) 🪢

Unofficial .NET SDK for Langfuse - the open-source LLM engineering platform.

Features

Feature	Description	Docs
OpenTelemetry Tracing	Export .NET OTEL traces to Langfuse	OTEL Integration
Prompt Management	Fetch, compile, and cache text & chat prompts	Prompt Management
Scores	Create user feedback and evaluation scores	Scores
Trace Management	List, get, and delete traces via API	Public API
Datasets	Create and manage evaluation datasets	Datasets
Experiments	Log agent runs with datasets	Experiments

Packages

Package	Description	Install
Langfuse.OpenTelemetry	Export OTEL traces to Langfuse	`dotnet add package Langfuse.OpenTelemetry`
Langfuse.Client	Prompt management, scores, traces, datasets, experiments	`dotnet add package Langfuse.Client`
Langfuse.Core	Shared config & types (auto-installed)	`dotnet add package Langfuse.Core`

Quick Start

Configuration

Set environment variables:

LANGFUSE_PUBLIC_KEY=pk-lf-...
LANGFUSE_SECRET_KEY=sk-lf-...
LANGFUSE_BASE_URL=https://cloud.langfuse.com  # EU region (default)
# LANGFUSE_BASE_URL=https://us.cloud.langfuse.com  # US region

OpenTelemetry Tracing

Export traces from any OTEL-instrumented library (including Semantic Kernel) to Langfuse:

using Langfuse.OpenTelemetry;
using OpenTelemetry;
using OpenTelemetry.Trace;

using var tracerProvider = Sdk.CreateTracerProviderBuilder()
    .AddSource("Microsoft.SemanticKernel*")
    .AddLangfuseExporter()
    .Build();

Langfuse Client

Access Langfuse features directly from .NET:

using Langfuse.Client;

var client = new LangfuseClient();

// Prompts, Scores, Datasets, Experiments

Documentation

Features - Detailed feature documentation
Testing Guide - How to run tests
Contributing - How to contribute

Running the Sample

cd samples/SemanticKernel.Sample
dotnet run

Check your Langfuse dashboard to see the traces.

License

MIT License - see LICENSE for details.

Product	Compatible and additional computed target framework versions.
.NET	net8.0 is compatible. net8.0-android was computed. net8.0-browser was computed. net8.0-ios was computed. net8.0-maccatalyst was computed. net8.0-macos was computed. net8.0-tvos was computed. net8.0-windows was computed. net9.0 is compatible. net9.0-android was computed. net9.0-browser was computed. net9.0-ios was computed. net9.0-maccatalyst was computed. net9.0-macos was computed. net9.0-tvos was computed. net9.0-windows was computed. net10.0 was computed. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed.

NuGet packages (2)

Showing the top 2 NuGet packages that depend on Langfuse.Core:

Package	Downloads
Langfuse.OpenTelemetry A bridge between .NET OpenTelemetry (OTEL) and Langfuse. Automatically exports OTEL traces to Langfuse with a single line of code.	1.5K
Langfuse.Client Unofficial .NET client for Langfuse. Provides access to Langfuse features like Prompt Management, with client-side caching.	998

GitHub repositories

This package is not used by any popular GitHub repositories.

Version	Downloads	Last Updated
1.4.1	255	1/19/2026
1.4.0	136	1/11/2026
1.3.0	146	1/9/2026
1.2.0	511	12/11/2025
1.1.0	317	12/8/2025