LangChain

What is LangChain?

LangChain is an open-source framework for building applications and agents on top of large language models, maintained alongside LangGraph and Deep Agents. The company also sells LangSmith, a hosted platform that covers the rest of the agent lifecycle: tracing and monitoring, online and offline evals, dataset collection, annotation queues, a prompt playground, and deployment of long-running agents with cron scheduling and authentication. Newer LangSmith services include Fleet for building agents in plain language, Engine for diagnosing agent failures, isolated Sandboxes for agent-generated code, and an LLM Gateway with cost controls and model fallbacks. Developers, AI engineers and enterprise teams use it to move agents from prototype to production with visibility into what they do. The open-source libraries are free, and LangSmith has a Developer plan at $0 per seat per month, a Plus plan at $39 per seat per month, and custom Enterprise pricing, all with pay-as-you-go usage on top.

Use cases

• Build LLM agents in code
• Trace and debug agent runs
• Evaluate prompts and agents with datasets
• Deploy long-running agents to production
• Run agent-generated code in sandboxes
• Control model costs and fallbacks with a gateway

Who it's for

• AI engineers
• Software developers
• Platform teams
• Enterprise AI teams

Why use LangChain

• One vendor provides both the open-source libraries and the hosted tooling to observe, evaluate and deploy agents.
• The free Developer plan lets a solo user trace and test agents before paying.
• Pay-as-you-go metering means the bill follows actual traces, deployments and sandbox usage.
• Plus adds unlimited seats at one per-seat price, which suits growing teams.
• Enterprise adds self-hosted or hybrid deployment, custom SSO and a support SLA.

LangChain features

• Open-source agent frameworks including LangChain, LangGraph and Deep Agents
• LangSmith tracing, monitoring and insights
• Online and offline evals with dataset collection
• Annotation queues for human feedback
• Prompt Hub and Playground
• Deployment of agents with 30+ API endpoints and cron scheduling
• Fleet for creating agents with everyday language
• Sandboxes for isolated execution of agent-generated code
• LLM Gateway with cost controls, model fallbacks and PII redaction
• Cloud, hybrid and self-hosted options on Enterprise

LangChain integrations

• MCP

How to get started with LangChain

1. Build an agent with the open-source LangChain, LangGraph or Deep Agents libraries.
2. Connect it to LangSmith so every run is traced and can be monitored and evaluated.
3. Collect datasets and feedback, then run evals to catch regressions.
4. Deploy the agent on LangSmith infrastructure or, on Enterprise, host the platform yourself.

LangChain limitations

• The Developer plan is limited to 1 seat and 5k base traces per month before pay-as-you-go
• Deployment, Engine and other services are not part of the Developer plan
• Self-hosted and hybrid options are on the Enterprise plan
• LangSmith usage is metered in LangChain units, so monthly cost varies with agent activity

LangChain pricing

Yes, LangChain has a free plan. Paid plans start at $39 per month, according to the official pricing page on 24 Oct 2026.

LangChain plans

• Developer

  $0 /seat per month

  then pay as you go

  • Up to 5k base traces / mo
  • Community support
  • 1 seat

• Plus

  $39 /seat per month

  then pay as you go

  • Up to 10k base traces / mo
  • Access to Deployment, Engine, and more
  • Add unlimited seats

• Enterprise

  Custom

  • Self-hosted and hybrid deployment options
  • Custom SSO, ABAC, and RBAC
  • Support SLA
  • Custom seats and workspaces

Plans as listed on the official pricing page on 24 Oct 2026. Prices can change and may vary by country or exclude tax. Check the official pricing page.

LangChain alternatives

The main LangChain alternatives listed on Debuly are LlamaIndex, Haystack, CrewAI, AutoGen, Semantic Kernel and Langfuse. The table compares pricing and platforms; order is A–Z.

1. 

   AutoGen

   Microsoft's MIT-licensed Python and .NET framework for multi-agent AI apps, now archived; new projects are pointed to Microsoft Agent Framework.

   Developer platformsAutomation and agentsCoding
   Open sourceVisit AutoGen (official site)
2. 

   CrewAI

   Multi-agent framework and platform for building AI agent crews in Python or a visual editor, then deploying and monitoring them.

   Developer platformsAutomation and agentsCoding
   Open sourceVisit CrewAI (official site)
3. 

   Haystack

   Open-source Python framework from deepset for building RAG pipelines, AI agents and multimodal apps from modular components.

   Developer platformsCodingAutomation and agents
   Open sourceVisit Haystack (official site)
4. 

   Langfuse

   Open-source LLM observability and evaluation platform for tracing agents, managing prompts and scoring outputs.

   Developer platformsAutomation and agentsCoding
   FreemiumVisit Langfuse (official site)
5. 

   LlamaIndex

   Open-source framework plus the LlamaParse platform for parsing, extracting and indexing documents so LLM apps can use them.

   Developer platformsResearch and searchAutomation and agents
   FreemiumVisit LlamaIndex (official site)
6. 

   Semantic Kernel

   Microsoft's open-source SDK for building AI agents and multi-agent systems in Python, .NET and Java, now succeeded by Microsoft Agent Framework.

   Developer platformsAutomation and agentsCoding
   Open sourceVisit Semantic Kernel (official site)

LangChain FAQ

Sources & verification

Facts on this page come from the official sources below, each with the date we read it. Written by Debuly; the vendor did not review this page.

Image credits

• Logo: from cdn.prod.website-files.com · fetched 23 Oct 2026 · Vendor trademark, used only to identify the product; removed on request
• Cover: from cdn.prod.website-files.com · fetched 23 Oct 2026 · Vendor marketing image from the official site; removed on request

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