Install custom dependencies
Langflow provides optional dependency groups and support for custom dependencies to extend Langflow functionality. This guide covers how to add dependencies for different Langflow installations, including Langflow Desktop and Langflow OSS.
The Langflow codebase uses two pyproject.toml files to manage dependencies, with one for base and one for main:
- The
mainpackage is managed by the root levelpyproject.toml, and it includes end-user features and main application code, such as Langchain and OpenAI. - The
basepackage is managed atsrc/backend/base/pyproject.toml, and it includes core infrastructure, such as the FastAPI web framework.
Install custom dependencies in Langflow Desktop
To add dependencies to Langflow Desktop, add an entry for the package to the application's requirements.txt file:
- On macOS, the file is located at
/Users/USER/.langflow/data/requirements.txt. - On Windows, the file is located at
C:\Users\USER\AppData\Roaming\com.Langflow\data\requirements.txt.
Add each dependency to requirements.txt on its own line in the format DEPENDENCY==VERSION, such as docling==2.40.0.
Restart Langflow Desktop to install the dependencies.
If you need to change or uninstall custom dependencies, edit the requirements.txt file, and then restart Langflow Desktop.
Install custom dependencies in Langflow OSS
To install your own custom dependencies in your Langflow environment, add them with your package manager.
If you're working within a cloned Langflow repository, add dependencies with uv add because there is already a pyproject.toml file for uv to reference:
_10uv add DEPENDENCY
Install optional dependency groups
Langflow OSS provides optional dependency groups that extend its functionality.
These dependencies are listed in the pyproject.toml file under [project.optional-dependencies].
Install dependency groups using pip's [extras] syntax. For example, to install Langflow with the postgresql dependency group, enter the following command:
_10uv pip install "langflow[postgresql]"
To install multiple extras, use commas to separate each dependency group:
_10uv pip install "langflow[local,postgresql]"
Use a virtual environment to test custom dependencies
When testing locally, use a virtual environment to isolate your dependencies and prevent conflicts with other Python projects.
For example, if you want to experiment with matplotlib with Langflow:
_10# Create and activate a virtual environment_10uv venv YOUR_LANGFLOW_VENV_10source YOUR_LANGFLOW_VENV/bin/activate_10_10# Install langflow and your additional dependency_10uv pip install langflow matplotlib
If you're working within a cloned Langflow repository, add dependencies with uv add to reference the existing pyproject.toml files:
_10uv add matplotlib
The uv add commands automatically update the uv.lock file in the appropriate location.
Add dependencies to the Langflow codebase
When contributing to the Langflow codebase, you might need to add dependencies to Langflow.
Langflow uses a workspace with two packages, each with different types of dependencies.
To add a dependency to the main package, run uv add DEPENDENCY from the project root.
For example:
_10uv add matplotlib
Dependencies can be added to the main package as regular dependencies at [project.dependencies] or optional dependencies at [project.optional-dependencies].
To add a dependency to the base package, navigate to src/backend/base and run:
_10cd src/backend/base && uv add DEPENDENCY
To add a development dependency for testing, linting, or debugging, navigate to src/backend/base and run:
_10cd src/backend/base && uv add --group dev DEPENDENCY
Dependencies can be added to the base package as regular dependencies at [project.dependencies], development dependencies at [dependency-groups.dev], or optional dependencies at [project.optional-dependencies].
You can optionally use make add instead of uv add:
_10# Equivalent to: uv add matplotlib_10make add main="matplotlib"_10_10# Equivalent to: cd src/backend/base && uv add --group dev matplotlib_10make add devel="matplotlib"_10_10# Equivalent to: cd src/backend/base && uv add matplotlib_10make add base="matplotlib"
Alternatively, you can add these dependencies manually to the appropriate pyproject.toml file:
_10[project]_10dependencies = [_10 "matplotlib>=3.8.0"_10]
Or as an optional dependency in the main package:
_10[project.optional-dependencies]_10plotting = [_10 "matplotlib>=3.8.0",_10]
Or as a development dependency in the base package:
_10[dependency-groups]_10dev = [_10 "matplotlib>=3.8.0",_10]
