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
Latest updates
- 2026-10-26 - LangSmith Cloud update
Workspace administration can be delegated by action through granular permissions; existing custom roles and the Workspace Admin role receive the permissions.
- 2026-10-19 - LangSmith Cloud update
A new sidebar is available in every workspace, and example creation now uses reference_outputs across the API and SDKs.
- 2026-10-12 - LangSmith Cloud update
Added tracing-only API keys and ScaleDown operations and model to the LLM Gateway.
- 2026-10-05 - LangSmith Cloud update
LangSmith added plain-language AI search for runs, traces, and threads alongside structured filters.
- The LangSmith MCP adds a query_runs tool that accepts the same parameters as the SDK’s client.runs.query() , including typed selects for costs, token breakdowns, and full inputs and outputs, with curs
The LangSmith MCP adds query_runs with typed selects and cursor pagination. It returns token counts and USD costs by default.
Capabilities
- Command line — “Sandbox CLI” source
- Self-hosted — “Self-hosted and hybrid deployment options” source
- API — “Trigger agent via API” source
- Builds agents and workflows — “Build agents fast with any model provider.” source
- Traces and evaluates — “Debug, monitor, and improve your AI applications with tracing and evals” source
Get it
Security
Pricing
- Starting price
- $39/user/mo
- Prices checked
- 2026-11-05
Developer
Free
- Up to 5k base traces / mo, then pay-as-you-go
- Community support
- 1 seat
- Fleet includes 7 LSU
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
- 1 free Serverless (Small) deployment included
- Fleet includes 37 LSU
Enterprise
Price on request
- Self-hosted and hybrid deployment options
- Custom SSO, ABAC, and RBAC
- Support SLA
- Custom seats and workspaces