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Install custom dependencies

To install custom dependencies in your Langflow environment, add them with your package manager.

Create a virtual environment for local testing​

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:


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# Create and activate a virtual environment
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uv venv YOUR_LANGFLOW_VENV
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source YOUR_LANGFLOW_VENV/bin/activate
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# Install langflow and your additional dependency
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uv pip install langflow matplotlib

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.


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uv add langflow matplotlib

Add dependencies to the Langflow project​

When contributing to Langflow itself, add dependencies to the project's configuration. Langflow uses a workspace with two packages:

  • The main package (root level): For end-user features and main application code
  • The base package (in src/backend/base): For core functionality and shared code

Dependencies can be added in different groups:

  • Regular dependencies: Core functionality needed to run the package
  • Development dependencies: Tools for testing, linting, or debugging are added in the [dependency-groups.dev] section
  • Optional dependencies: Features that users can optionally install are added in the[project.optional-dependencies]

There are three ways to add a package using make commands:

  • Add to main package dependencies (for end-user features):

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make add main="matplotlib"

  • Add to development tools (for testing, linting, debugging):

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make add devel="matplotlib"

  • Add to base package dependencies (for core functionality):

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make add base="matplotlib"

You can also add these dependencies manually to the pyproject.toml file:


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[project]
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dependencies = [
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"matplotlib>=3.8.0"
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]

  • Or as an optional dependency:

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[project.optional-dependencies]
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plotting = [
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"matplotlib>=3.8.0",
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]

The make commands add the dependency with uv add and update the uv.lock file in the appropriate location.

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