LangChain.js, originally designed for Node.js, has expanded its compatibility to include browsers, Cloudflare Workers, Vercel/Next.js, Deno, Supabase Edge Functions, and other JavaScript environments in response to community feedback. This expansion required transitioning the codebase to ESM, eliminating node-only APIs, and revising how third-party integrations are handled to avoid bloated bundle sizes. The new import structure for LangChain.js ensures that only necessary code is included, preventing issues related to optional dependencies. While these changes introduced some breaking alterations, such as more granular imports for third-party integrations, the transition aims to enhance user experience across various environments. The team rigorously tests compatibility using environment-specific starter projects to ensure stability and invites contributions to support additional environments.