Contribute to Langflow

This guide is intended to help you start contributing to Langflow. As an open-source codebase in a rapidly developing field, Langflow welcomes contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.

To contribute code or documentation to Langflow, follow the fork and pull request quickstart.

Install Langflow from source

Install Langflow from source by forking the repository, and then set up your development environment using Make.

Prerequisites

• uv version 0.4 or later
• Node.js
• Make (Linux and macOS only)

Clone the Langflow repository

1. Fork the Langflow GitHub repository.

2. Add the new remote to your local repository on your local machine:

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git remote add FORK_NAME https://github.com/GIT_USERNAME/langflow.git

Replace the following:

• FORK_NAME: A name for your fork of the repository
• GIT_USERNAME: Your Git username

Run Langflow from source

You can run Langflow from source after cloning the repository, even if you aren't contributing to the codebase.

Run from source on macOS/Linux

In your terminal, navigate to the root of the Langflow directory, and then run make run_cli.

This command does the following:

• Installs frontend and backend dependencies
• Builds the frontend static files
• Starts the application with default settings

The Langflow frontend is served at http://localhost:7860.

Run from source with Windows CMD

To run Langflow from source on Windows, you can use the Langflow repository's included scripts, or run the commands in the terminal.

Do one of the following:

• To install and run Langflow with the included Windows Batch file, navigate to the scripts/windows directory, and then run the build_and_run.bat file.

• To run Langflow from the Windows Command Line:

  1. Build the Langflow frontend:

     
     

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     cd src/frontend && npm install && npm run build && npm run start

     
     

  2. Copy the contents of the built src/frontend/build directory to src/backend/base/langflow/frontend.

  3. Start Langflow:

     
     

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     uv run langflow run

     
     

The Langflow frontend is served at http://localhost:7860.

Run from source with Powershell

To run Langflow from source on Windows, you can use the Langflow repository's included scripts, or run the commands in the terminal.

Do one of the following:

• To install and run Langflow with the included scripts, navigate to the scripts/windows directory, and then run the build_and_run.ps1 file.

• To run Langflow from a Powershell terminal:

  1. Run the following commands separately to build the Langflow frontend:

     
     

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     cd src/frontend

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     npm install

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     npm run build

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     npm run start

     
     

  2. Copy the contents of the built src/frontend/build directory to src/backend/base/langflow/frontend.

  3. Start Langflow:

     
     

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     uv run langflow run

     
     

The Langflow frontend is served at http://localhost:7860.

Set up your Langflow development environment

Linux or macOS

1. Set up the Langflow development environment:

   
   

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   make init

   
   

   This command sets up the development environment by doing the following:

   • Checking for uv and npm.
   • Installing backend and frontend dependencies.
   • Installing pre-commit hooks.

2. Run the backend and frontend in separate terminals for development:

   
   

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   # Run backend in development mode (includes hot reload)

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   make backend

   
   
   
   

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   # In another terminal, run frontend in development mode (includes hot reload)

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   make frontend

   
   

   The make backend and make frontend commands automatically install dependencies, so you don't need to run install commands separately.

   The frontend is served at http://localhost:7860.

3. Optional: Install pre-commit hooks to help keep your changes clean and well-formatted.

   With pre-commit hooks installed, you must use uv run git commit instead of git commit directly.

   make init installs pre-commit hooks automatically, or you can run the following command to install them manually:

   
   

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   uv sync

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   uv run pre-commit install

   
   

4. To test your changes before pushing commits, run make lint, make format, and make unit_tests. To run all tests, including coverage, unit, and integration, tests, run make tests.

Windows

Since Windows doesn't include make, building and running Langflow from source uses npm and uv.

To set up the Langflow development environment, run the frontend and backend in separate terminals:

1. To run the frontend, run the following commands:

   
   

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   cd src/frontend

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   npm install

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   npm run start

   
   

2. In a separate terminal, run the following command to run the backend:

   
   

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   uv run langflow run --backend-only

   
   

The frontend is served at http://localhost:7860.

Debug

The repo includes a .vscode/launch.json file for debugging the backend in VSCode, which is faster than debugging with Docker Compose. To debug Langflow with the launch.json file in VSCode:

For more information, see the VSCode documentation.

Additional contribution guides

• Contribute bundles
• Contribute components
• Contribute tests
• Contribute templates

Contribute documentation

The documentation is built using Docusaurus and written in Markdown. For style guidance, see the Google Developer Documentation Style Guide.

1. Install Node.js and Yarn

2. Fork the Langflow GitHub repository.

3. Add the new remote to your local repository on your local machine:

   
   

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   git remote add FORK_NAME https://github.com/GIT_USERNAME/langflow.git

   
   

   Replace the following:

   • FORK_NAME: A name for your fork of the repository
   • GIT_USERNAME: Your Git username

4. From the root of your local Langflow fork, change to the /docs directory:

   
   

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   cd docs

   
   

5. Install dependencies and start a local Docusaurus static site with hot reload:

   
   

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   yarn install

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   yarn start

   
   

   The documentation is served at localhost:3000.

6. To edit and create content, work with the .mdx files in the langflow/docs/docs directory.

   Create new files in .mdx format.

   Navigation is defined in langflow/docs/sidebars.js.

   Most pages use a slug for shorthand cross-referencing, rather than supplying the full or relative directory path. For example, if a page has a slug of /cool-page, you can link to it with [Cool page](/cool-page) from any other /docs page.

7. Recommended: After making some changes, run yarn build to build the site locally with more robust logging. This can help you find broken links before creating a PR.

Open a pull request

To submit a pull request, do the following:

1. Open a new GitHub pull request with your patch against the main branch.
2. Ensure the PR title follows semantic commit conventions. For example, features are feat: add new feature and fixes are fix: correct issue with X.

Some additional guidance on pull request titles:

• Ensure the pull request description clearly describes the problem and solution. If the PR fixes an issue, include a link to the fixed issue in the PR description with Fixes #1234.
• Pull request titles appear in Langflow's release notes, so they should explain what the PR does as explicitly as possible.
• Pull requests should strive to fix one thing only, and should contain a good description of what is being fixed.

3. A Langflow maintainer will review your pull request and may request changes, so ensure you pay attention to your PRs. Thanks for your contribution!

For more information, see the Python Developer's Guide.