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LangStream

Free

Framework for building and running event-driven LLM applications using no-code and Python (including LangChain-based) agents. ![GitHub Repo stars](https://img.shields.io/github/stars/LangStream/langstream?style=social)

FreeFree tier
Type
Open Source
Visit Website GitHub (40 stars)

About LangStream

LangStream is an open-source, event-driven developer platform for building and running LLM AI applications. It is powered by Kubernetes and Apache Kafka (or Apache Pulsar) and supports both no-code configuration and Python-based agents, including LangChain-based agents. The platform provides a CLI for local development, sample applications (e.g., OpenAI chat completions), and production-ready deployment on Kubernetes clusters such as Amazon EKS, Azure AKS, Google GKE, and Minikube. It also includes a web service, API gateway, and supports S3-compatible storage for code.

Key Features

Event-driven architecture for LLM applications
No-code and Python (including LangChain-based) agent support
Powered by Kubernetes and Apache Kafka or Apache Pulsar
CLI for local development and testing
Sample applications (e.g., OpenAI chat completions)
Production-ready deployment on Kubernetes (EKS, AKS, GKE, Minikube)
REST API gateway and authentication (JWT)
Web service and admin client
S3 API-compatible storage for code
Community support via Slack and Linen

Pros & Cons

Pros
  • Open-source and free
  • Event-driven architecture enables scalable and real-time AI apps
  • Supports both no-code simplicity and Python flexibility
  • Production-ready with Kubernetes deployment
  • Active community on Slack and GitHub
  • CLI tooling for easy local development
  • Integration with multiple message brokers (Kafka, Pulsar)
Cons
  • Requires Java 11+ to run the CLI
  • Production deployment requires Kubernetes and external storage (S3), increasing complexity
  • Dependency on Apache Kafka or Apache Pulsar
  • Documentation may be incomplete or evolving
  • Relatively small community compared to larger frameworks

Best For

Building event-driven LLM AI applicationsRunning chat completion applications with streamingDeploying AI apps on Kubernetes with Kafka or PulsarRapid prototyping with no-code agentsProduction-grade LLM app orchestration

FAQ

What are the prerequisites for running LangStream?
The CLI requires Java 11+ to be installed. For production deployment, you need a Kubernetes cluster (EKS, AKS, GKE, or Minikube) and external components like Apache Kafka or Apache Pulsar, plus S3-compatible storage.
How can I install the LangStream CLI?
You can install the CLI using Homebrew on macOS (brew install LangStream/langstream/langstream) or via a binary installation script: curl -Ls 'https://raw.githubusercontent.com/LangStream/langstream/main/bin/get-cli.sh' | bash. Verify with 'langstream -V'.
Is LangStream free to use?
Yes, LangStream is open-source and free. You can run it locally with Docker or deploy on Kubernetes without any licensing costs.
Does LangStream support non-OpenAI models?
LangStream supports Python agents (including LangChain), so you can integrate with any model provider supported by LangChain or custom Python code. The sample app uses OpenAI, but the platform is model-agnostic.