--- title: "Reflections on Three Years of Building LangChain" url: https://daily.dev/posts/reflections-on-three-years-of-building-langchain-qufxhrtzp source_url: https://www.langchain.com/blog/three-years-langchain type: article source: "LangChain" published: 2026-08-26T16:33:56.431Z updated: 2026-08-26T16:44:30.129Z tags: ["llm", "ai-agents", "venture-capital", "langchain", "langgraph"] reading_time: 9 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Reflections on Three Years of Building LangChain **[LangChain](https://daily.dev/sources/langchain)** · 9 min read · 0 upvotes · 0 comments ## Summary Harrison Chase, founder of LangChain, reflects on the company's three-year journey from a side-project open source Python package to a $1.25 billion company. The post recounts the launches of LangSmith (observability/evals) and LangGraph (a controllable agent runtime), and announces LangChain 1.0 - a ground-up rewrite focused on a core tool-calling loop, a new middleware concept for context engineering, and built on LangGraph's runtime. It also announces a $125 million Series B funding round and the evolution of LangSmith into a broader 'agent engineering platform' that now includes deployments. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is new in LangChain 1.0 compared to earlier versions? LangChain 1.0 is a ground-up rewrite focused on the core tool-calling loop that defines agents, adding a new middleware concept for controlling the context engineering lifecycle, and building on the LangGraph runtime for streaming, durable execution, and human-in-the-loop support. Older 0.x versions remain available as langchain-classic for continued support. _Track major framework rewrites like this one as you plan an agent stack migration on daily.dev._ ### What is the difference between LangChain and LangGraph? LangChain is the higher-level framework designed to make it easy to get started building agents, while LangGraph is the underlying production runtime providing streaming, statefulness, human-in-the-loop, and durable execution. LangChain 1.0 is now built directly on top of LangGraph rather than existing as a separate, less controllable abstraction. _Compare agent framework tradeoffs like this one before picking a stack on daily.dev._ ### How much funding did LangChain raise and at what valuation? LangChain raised a $125 million funding round at a $1.25 billion valuation, announced alongside the LangChain 1.0 release. The funding is earmarked for expanding LangSmith into a broader agent engineering platform and growing open source contributions. _Follow funding and product shifts like this to gauge which agent tools are gaining momentum, on daily.dev._ ## Similar posts on daily.dev - [Reflections on Three Years of Building LangChain](https://daily.dev/posts/reflections-on-three-years-of-building-langchain-1qbekvadm) · LangChain · 11 upvotes · 0 comments - [LangChain raises $125M to build the platform for agent engineering](https://daily.dev/posts/langchain-raises-125m-to-build-the-platform-for-agent-engineering-yoaitytpt) · LangChain · 0 upvotes · 0 comments - [LangChain raises $125M to build the platform for agent engineering](https://daily.dev/posts/langchain-raises-125m-to-build-the-platform-for-agent-engineering-6pbhh5utn) · LangChain · 5 upvotes · 0 comments - [Open source agentic startup LangChain hits $1.25B valuation](https://daily.dev/posts/open-source-agentic-startup-langchain-hits-1-25b-valuation-cp8ytqp3y) · TechCrunch · 0 upvotes · 0 comments - [LangChain's Second Birthday](https://daily.dev/posts/langchain-s-second-birthday-gtx6fvbxv) · LangChain · 0 upvotes · 0 comments --- Tags: [#llm](https://daily.dev/tags/llm), [#ai-agents](https://daily.dev/tags/ai-agents), [#venture-capital](https://daily.dev/tags/venture-capital), [#langchain](https://daily.dev/tags/langchain), [#langgraph](https://daily.dev/tags/langgraph) [View this post on daily.dev](https://daily.dev/posts/reflections-on-three-years-of-building-langchain-qufxhrtzp)