LangChain
An open-source framework for building LLM applications and AI agents — chains, tools, memory, and retrieval.
Plan details last verified 2026-10-05 · free plan available · developer API available · open source
What it does
Structuring LLM apps (agents, RAG, tool use) without rebuilding the plumbing every time.
Main features
- Chain and agent abstractions
- Tool/function calling integrations
- Document loaders and vector-store integrations
- LangSmith for tracing and evaluation
Best use cases
- Building AI agents with tool access
- RAG applications
- Prototyping multi-step LLM workflows
Getting started (beginner-friendly)
Follow the quickstart in the docs with Python or JavaScript — a basic chain is about ten lines of code.
Strengths
- Open source with a large community
- Works with many model providers
- Rich examples and docs
Limitations
- Abstractions add learning overhead
- Fast-moving APIs between versions
Pricing (verified summary)
The frameworks are free and open source; hosted LangSmith observability has free and paid tiers. Verify current details on LangChain's site.
Last checked 2026-10-05. Plan details change often — always confirm on the official site before purchasing.
Platforms
Self-hosted chains keep data in your infrastructure; hosted tracing sends telemetry to LangChain — configure accordingly.
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