📊 analytics

LangSmith costs $35/mo.
These cost $0.

8 free alternatives to LangSmith, checked for license, recent activity and real adoption. Each one tells you the catch, so you can switch with your eyes open.

⚡ Quick Verdict · 2027 Guide

The top-rated free, open-source replacement for LangSmith is Langfuse (Open Source Open Source). Across this category, 5 self-hostable tools are available (including Langfuse and Arize Phoenix). Switching a 5-person team saves up to $2,100/year compared to LangSmith's $35/mo subscription.

The catch: Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.

See the 8 picks ↓

LangSmith vs Free Alternatives

Quick side-by-side comparison · $0/mo vs $35/mo

Alternative	Type	License	Where It Runs	Stars	Head-to-Head
Langfuse	open source	Open Source	Self-host	★ 37.1k	LangSmith vs Langfuse →
Arize Phoenix	open source	Open Source	Self-host	★ 12.2k	LangSmith vs Arize Phoenix →
OpenLLMetry	open source	Open Source	Local	★ 7.5k	LangSmith vs OpenLLMetry →
Helicone	open source	Open Source	Local	★ 6.3k	LangSmith vs Helicone →
LangWatch	open source	Open Source	Local	★ 5k	LangSmith vs LangWatch →
Latitude	open source	Open Source	Self-host	★ 4.7k	LangSmith vs Latitude →
OpenLIT	open source	Open Source	Self-host	★ 3k	LangSmith vs OpenLIT →
Spanlens	open source	Open Source	Self-host	★ 13	LangSmith vs Spanlens →

The picks

8 open source · ranked by fit

01
Langfuse
open sourceOpen SourceSelf-host
37.1knov 2026
Langfuse provides tracing, evaluations, prompt management, and analytics to debug and improve LLM applications.
The catch vs LangSmith
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Install, platforms & data +
platforms
webself-hosteddocker to self-host
install
Clone https://github.com/langfuse/langfuse or deploy with Docker Compose
setup
Deploy via Docker or binary release from GitHub and configure environment variables.
your data
All application data and configuration live on your own server or local database.
checked
2026-11-07
Visit langfuse.com ↗Source Compare vs LangSmith →also replaces 8 other apps →
02
Arize Phoenix
open sourceOpen SourceSelf-host
12.2knov 2026
Open-source platform for LLM tracing, evaluation, and optimization. Features automatic instrumentation, prompt playground, and real-time AI application monitoring.
The catch vs LangSmith
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Install, platforms & data +
platforms
webself-hosteddocker to self-host
install
Clone https://github.com/arize-ai/phoenix or deploy with Docker Compose
setup
Deploy via Docker or binary release from GitHub and configure environment variables.
your data
All application data and configuration live on your own server or local database.
checked
2026-11-07
Visit arize.com ↗Source Compare vs LangSmith →also replaces 8 other apps →
03
OpenLLMetry
open sourceOpen SourceLocal
7.5knov 2026
Open-source observability platform for LLMs using OpenTelemetry. Monitor performance, track costs, and debug AI applications with just 2 lines of code.
The catch vs LangSmith
Community-driven open source project without dedicated enterprise SLAs.
Install, platforms & data +
platforms
desktopcross-platformone-click install
install
Clone https://github.com/traceloop/openllmetry or deploy with Docker Compose
setup
Download the native package or installer for your operating system.
your data
All application data lives locally on your own machine.
checked
2026-11-07
Visit traceloop.com ↗Source Compare vs LangSmith →also replaces 4 other apps →
04
Helicone
open sourceOpen SourceLocal
6.3knov 2026
Open-source platform for logging, monitoring, and debugging LLM applications. Route, debug, and analyze AI apps with comprehensive observability tools.
The catch vs LangSmith
Community-driven open source project without dedicated enterprise SLAs.
Install, platforms & data +
platforms
desktopcross-platformone-click install
install
Clone https://github.com/helicone/helicone or deploy with Docker Compose
setup
Download the native package or installer for your operating system.
your data
All application data lives locally on your own machine.
checked
2026-11-07
Visit helicone.ai ↗Source Compare vs LangSmith →also replaces 5 other apps →
05
LangWatch
open sourceOpen SourceLocal
5knov 2026
Tests AI agents through multi-turn simulations, LLM-based scoring, and production tracing so teams can ship reliable agents with confidence.
The catch vs LangSmith
Community-driven open source project without dedicated enterprise SLAs.
Install, platforms & data +
platforms
desktopcross-platformone-click install
install
Clone https://github.com/langwatch/langwatch or deploy with Docker Compose
setup
Download the native package or installer for your operating system.
your data
All application data lives locally on your own machine.
checked
2026-11-07
Visit langwatch.ai ↗Source Compare vs LangSmith →also replaces 6 other apps →
06
Latitude
open sourceOpen SourceSelf-host
4.7knov 2026
Open-source platform for monitoring AI agents: captures traces, surfaces failure patterns, alerts on issues, and helps you verify fixes with automated evals.
The catch vs LangSmith
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Install, platforms & data +
platforms
webself-hosteddocker to self-host
install
Clone https://github.com/latitude-dev/latitude-llm or deploy with Docker Compose
setup
Deploy via Docker or binary release from GitHub and configure environment variables.
your data
All application data and configuration live on your own server or local database.
checked
2026-11-07
Visit latitude.so ↗Source Compare vs LangSmith →also replaces 6 other apps →
07
OpenLIT
open sourceOpen SourceSelf-host
3knov 2026
Open-source observability platform for GenAI and LLM applications. Real-time monitoring, distributed tracing, prompt management, and AI model evaluation built on OpenTelemetry.
The catch vs LangSmith
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Install, platforms & data +
platforms
webself-hosteddocker to self-host
install
Clone https://github.com/openlit/openlit or deploy with Docker Compose
setup
Deploy via Docker or binary release from GitHub and configure environment variables.
your data
All application data and configuration live on your own server or local database.
checked
2026-11-07
Visit openlit.io ↗Source Compare vs LangSmith →also replaces 5 other apps →
08
Spanlens
open sourceOpen SourceSelf-host
13nov 2026
Drop-in observability platform for OpenAI, Anthropic, and Gemini that logs every request, tracks costs, traces agent workflows, and flags anomalies and PII.
The catch vs LangSmith
Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.
Install, platforms & data +
platforms
webself-hosteddocker to self-host
install
Clone https://github.com/spanlens/Spanlens or deploy with Docker Compose
setup
Deploy via Docker or binary release from GitHub and configure environment variables.
your data
All application data and configuration live on your own server or local database.
checked
2026-11-07
Visit spanlens.io ↗Source Compare vs LangSmith →also replaces 3 other apps →

LangSmith Head-to-Head Comparisons (2027)

Side-by-side trade-off breakdowns · 8 free alternatives

LangSmith vs LangfuseOpen Source · Self-host →

LangSmith vs Arize PhoenixOpen Source · Self-host →

LangSmith vs OpenLLMetryOpen Source · Local →

LangSmith vs HeliconeOpen Source · Local →

LangSmith vs LangWatchOpen Source · Local →

LangSmith vs LatitudeOpen Source · Self-host →

LangSmith vs OpenLITOpen Source · Self-host →

LangSmith vs SpanlensOpen Source · Self-host →

Frequently Asked Questions

Direct answers · LangSmith open-source replacements

What is the best free alternative to LangSmith?+

The top free alternative to LangSmith is Langfuse (open source, Open Source). Langfuse provides tracing, evaluations, prompt management, and analytics to debug and improve LLM applications. Other popular LangSmith replacements include Arize Phoenix, OpenLLMetry, Helicone.

Can I self-host a free replacement for LangSmith?+

Yes. Of the 8 free alternatives to LangSmith, 5 can be self-hosted on your own server or local machine: Langfuse (Open Source), Arize Phoenix (Open Source), Latitude (Open Source), OpenLIT (Open Source), Spanlens (Open Source).

How much does switching from LangSmith to a free alternative save?+

LangSmith starts at $35/month per seat ($420/year). Switching a 5-person team to a free alternative like Langfuse saves $2,100 per year in software subscription fees.

Should I vibe-code or build my own LangSmith clone from scratch?+

Our build verdict for LangSmith is NO (use a free alternative, save the tokens). Instead of paying recurring SaaS fees for LangSmith or rebuilding it from scratch, deploy one of the 8 battle-tested open-source alternatives like Langfuse.

What is the catch when switching from LangSmith to Langfuse?+

Requires self-hosting setup, updates, and server maintenance compared to managed LangSmith.