What is PEP 723?

PEP 723 defines a standard format for directly embedding dependency and environment information in Python scripts. This enables standalone scripts to specify their requirements without external configuration files.

Key Features

Metadata Format

• Uses commented TOML syntax
• Specifies dependencies
• Declares Python version requirements
• Supports environment markers

Integration

• Tool-agnostic specification
• Compatible with existing editors
• Supports script portability

Impact

This PEP simplifies script distribution and execution by allowing dependencies to be self-contained within the script file. See How to write self-contained Python scripts using PEP 723 for a practical guide.

Tools that support PEP 723

• uv runs a PEP 723 script with uv run script.py, creating an ephemeral environment from the inline metadata.
• pipx runs the same scripts with pipx run script.py.
• Hatch and PDM support PEP 723 via hatch run and pdm run.
• pip added the --requirements-from-script flag in 26.0 (January 2026), which installs the dependencies declared in the inline metadata without running the script itself.

Learn More

• PEP 723 Specification
• Inline Script Metadata Guide
• Use of inline script metadata with uv

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