langchain
The agent engineering platform
The Lens
By Erik Loyd, SaaS CEO and former COO/CFO of an AWS Premier Partner.
Updated Oct 2026
LangChain is the glue layer for LLM apps: one standard interface for models, vector stores and tools, plus create_agent, a small harness that builds an agent from a model, tools and a prompt. Swap OpenAI for Anthropic or local Ollama without a rewrite. LangChain, LangGraph and Deep Agents are all MIT and free.
There's nothing to host. uv add langchain and you're writing code. The ops work is upgrades: patches can land a few times a week, though since 1.0 breaking changes wait for major versions. Still on 0.3? Its maintenance window closes in December 2026.
The paywall is LangSmith, their hosted tracing, evals and deployment platform. Developer is free for one seat and 5k traces a month. Plus is $39 per seat per month with 10k traces, then usage billing. Self-hosted LangSmith is Enterprise only. Solo: free. Small teams: Plus, or send traces to Langfuse instead. Large teams: Enterprise for SSO or self-hosting.
The catch: a single chat call is simpler with the provider SDK, and when a chain misbehaves you debug LangChain's internals. Security too. langchain-core has shipped a steady run of advisories, including a critical serialization bug that could leak secrets (CVE-2025-68664). Pin versions and patch fast.
Free vs Self-Hosted vs Paid
open coreFree: The framework is MIT with no feature gates: langchain, langchain-core, LangGraph, Deep Agents and the partner integration packages (OpenAI, Anthropic, Ollama, Groq, Mistral and more). LangSmith Developer plan: $0 for 1 seat, up to 5k base traces a month, community support, plus small monthly allowances for Fleet (7 LSU) and Sandboxes (8 LSU).
Self-hosted: The framework is a library that runs inside your own process, so there's no server to run; you pay your model provider directly. Self-hosted or hybrid LangSmith is only available on Enterprise. Open source tracing alternatives such as Langfuse and Arize Phoenix plug into LangChain if you want observability without a LangSmith bill.
Paid: LangSmith Plus is $39 per seat per month (unlimited seats, billed monthly, self-serve) with 10k base traces a month included, then pay-as-you-go at 0.005 LSU per extra base trace, where 1 LSU = $1. Base traces keep 14 days of history; extended traces keep 180 days for an extra fee. Plus also includes 1 free small serverless agent deployment, with further deployments metered by compute and memory. Enterprise is custom priced, invoiced annually, and adds custom SSO, ABAC/RBAC, a support SLA and cloud, hybrid or self-hosted LangSmith. VC-backed startups can get up to $10,000 in credits.
The framework is free under MIT. LangSmith is free for one seat and 5k traces a month; teams pay $39 per seat per month plus 0.005 LSU ($1 each) per trace past the 10k allowance.
What to do by team size
- Solo
- free; MIT framework plus the free LangSmith Developer seat with 5k traces a month
- Small team
- free framework; LangSmith Plus at $39 per seat per month, or self-host Langfuse for tracing
- Medium team
- free framework; LangSmith Plus, but watch the per-trace usage bill past 10k traces a month
- Large team
- free framework; LangSmith Enterprise for custom SSO, RBAC and hybrid or self-hosted deployment
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License: MIT License
Use freely, including commercial. Just keep the license.
Commercial use: ✓ Yes
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