Submit
Ad
Learn more

Open Source LLM Observability & Evaluation using JavaScript

A curated collection of the best open source tracing, monitoring, and evaluation platforms for LLM and AI-agent applications. using JavaScript.

Langfuse

AI
Open source LLM engineering platform for AI-powered applications

  • Stars

    Stars growing over the last 30 days36,898

  • Last commit

    8 hours ago

  • License

    MIT
Langfuse provides tracing, evaluations, prompt management, and analytics to debug and improve LLM applications.

Open Source Alternative to:

LangSmith

Arize Phoenix

AI
Open-source LLM tracing & evaluation for AI optimization

  • Stars

    Stars growing over the last 30 days12,106

  • Last commit

    9 hours ago

  • License

    Elastic-2.0
Open-source platform for LLM tracing, evaluation, and optimization. Features automatic instrumentation, prompt playground, and real-time AI application monitoring.

Open Source Alternative to:

LangSmith

Helicone

AI
Build reliable AI apps with comprehensive observability

  • Stars

    6,254

  • Last commit

    5 days ago

  • License

    Apache-2.0
Open-source platform for logging, monitoring, and debugging LLM applications. Route, debug, and analyze AI apps with comprehensive observability tools.

Open Source Alternative to:

DataDog

Agenta

AI
Build, automate, and improve AI agents with your team

  • Stars

    4,881

  • Last commit

    8 hours ago

  • License

    MIT
Open-source workspace for building and running AI agents: chat-driven development, scheduling, human-in-the-loop approvals, versioning, and tracing. Self-host or use the cloud.

Open Source Alternative to:

ChatGPT Work

Latitude

AI
Full observability for AI agents in production

  • Stars

    4,742

  • Last commit

    13 hours ago

  • License

    MIT
Open-source platform for monitoring AI agents: captures traces, surfaces failure patterns, alerts on issues, and helps you verify fixes with automated evals.

Open Source Alternative to:

LangSmith

LangWatch

AI
Simulation-based testing and evaluation for AI agents

  • Stars

    5,004

  • Last commit

    8 hours ago

  • License

    Apache-2.0
Tests AI agents through multi-turn simulations, LLM-based scoring, and production tracing so teams can ship reliable agents with confidence.

Open Source Alternative to:

LangSmith

Laminar

AI
AI-powered platform for engineering LLM products

  • Stars

    Stars growing over the last 30 days3,471

  • Last commit

    9 hours ago

  • License

    Apache-2.0
Laminar is an open-source platform that helps collect, understand, and utilize data for building high-quality LLM applications.

Open Source Alternative to:

LangChain

OpenLIT

AI
Monitor, debug, and scale LLM applications with ease

  • Stars

    Stars growing over the last 30 days2,899

  • Last commit

    8 hours ago

  • License

    Apache-2.0
Open-source observability platform for GenAI and LLM applications. Real-time monitoring, distributed tracing, prompt management, and AI model evaluation built on OpenTelemetry.

Open Source Alternative to:

LangSmith

mlop

AI
Experiment tracking platform for ML teams

  • Stars

    394

  • Last commit

    8 months ago

  • License

    Apache-2.0
Open source ML experiment tracking platform with parameter and gradient logging, media tracking, real-time alerts, and full Weights & Biases API compatibility.

Open Source Alternative to:

Weights and Biases

Spanlens

AI
LLM observability: cost, latency, and traces in one place

  • Stars

    13

  • Last commit

    22 hours ago

  • License

    MIT
Drop-in observability platform for OpenAI, Anthropic, and Gemini that logs every request, tracks costs, traces agent workflows, and flags anomalies and PII.

Open Source Alternative to:

LangSmith
Ad