Laminar: Open Source Alternative to LangSmith

Laminar is an AI-powered platform for engineering LLM products with 3k+ GitHub stars — a LangSmith alternative for agent observability, evaluation, and debugging.

Compare Laminar with Weights & Biases and Datadog before you choose your stack.

Key features

Observability

• Distributed tracing for LLM chains and agents
• Signal alerts for anomalies and performance issues
• Real-time monitoring of model quality and latency
• Custom metrics and dashboards
• Integration with OpenTelemetry

Evaluation & testing

• Automated evals with custom scorers
• Regression testing for prompt changes
• Side-by-side comparison of model versions
• Human-in-the-loop annotation
• Dataset management for evals

Debugging

• Trace visualization with input/output inspection
• Error tracking and root cause analysis
• Prompt version diffing
• Latency breakdown by component
• Cost attribution per trace

Developer experience

• Python and TypeScript SDKs
• REST API for custom integrations
• Webhook alerts to Slack, Discord, email
• Team collaboration and role-based access
• Self-hosted and cloud options

Laminar vs LangSmith

	Laminar	LangSmith
License	Apache-2.0 (open source)	Proprietary
Models	Bring your own keys / local models	Vendor-locked models
Deployment	Self-hosted or cloud	SaaS only
Privacy	Data stays on your infrastructure	Processed by vendor
Cost	Free software + API usage	Subscription pricing

Choose Laminar if you want open-source code, self-hosting options, and full control over your data and deployment.

Choose LangSmith if you prefer a managed proprietary product with vendor support and minimal setup.

Browse more open-source alternatives to LangSmith, or explore other tools in Developer Tools.

At a glance

License	Apache-2.0
Stack	Python, TypeScript, PostgreSQL
Self-hosted	Yes — Laminar OSS
Cloud	lmnr.ai (managed)
Tracing	OpenTelemetry-compatible

Self-hosting

git clone https://github.com/lmnr-ai/lmnr.git

Laminar can be self-hosted for full control over your data. The cloud version provides managed infrastructure and automatic updates.

FAQ

Is Laminar a free alternative to LangSmith?

Yes. Laminar is open source under Apache-2.0. You can self-host it at no software cost — you only pay for infrastructure or optional managed services.

How does Laminar compare to LangSmith?

Laminar gives you source code access, self-hosting, and data ownership. LangSmith is a proprietary product focused on managed convenience. See the comparison table above for a side-by-side breakdown.

Can I self-host Laminar?

Yes. Laminar supports self-hosted deployment, which is a core reason teams choose it over LangSmith. Check the Getting started or Self-hosting section for install commands.

Is Laminar suitable for production?

Laminar is actively maintained with a strong open-source community. Many teams run it in production as a Developer Tools alternative to LangSmith. Review the At a glance table for license and stack details.

What are alternatives to Laminar and LangSmith?

Browse alternatives to LangSmith for more open-source options, including tools compared to Weights & Biases. Explore the full Developer Tools category for related projects.