tools
LangChain Review 2026 — Top Open-Source LLM Framework
LangChain is the most popular open-source framework for building LLM apps. 90K+ GitHub stars, 600+ integrations, LangGraph for agents, LangSmith for observability.
LangChain provides pre-built agent architectures, integrations, middleware, and a durable runtime for building applications that use language models, tools, and data sources.
Developers use it to create agents, connect models and tools, add human approval, persist state, and customize agent behavior. LangChain itself is free and MIT-licensed; LangSmith services for tracing, evaluation, deployment, and other operations are priced separately.
Features
- Pre-built agent architectures and templates
- Integrations with models, tools, databases, and data sources
- Middleware hooks for approval, context compression, and data removal
- Persistence, rewind, checkpointing, and human-in-the-loop support
- Model and tool swapping without rewriting applications
- MIT-licensed open-source library
- Integration with LangSmith for tracing, evaluation, and deployment
Use cases
- Build agents that call tools and model providers
- Connect agents to databases and external data sources
- Add human approval to sensitive agent actions
- Persist and resume long-running agent workflows
- Route requests between models based on task requirements
Pros
Cons
Pricing
- Starting price
- Free
- Pricing checked
- 2026-09-19
Developer
$0 / seat per month
- Up to 5k base traces / mo, then pay-as-you-go
- Community support
- 1 seat
Plus
$39 / seat per month
- Up to 10k base traces / mo, then pay-as-you-go
- Access to Deployment, Engine, and more
- Add unlimited seats
Enterprise
Custom pricing
- Self-hosted and hybrid deployment options
- Custom SSO, ABAC, and RBAC
- Support SLA
- Custom seats and workspaces