fastapi-slim

FastAPI framework, high performance, easy to learn, fast to code, ready for production

fastapi-slim v0.129.1 83.4K downloads/30d#14,077 on PyPI★ 101,604

Permissive license MIT Active released 2026-02-21

What it is and what it does

fastapi-slim is a deprecated shim package that does nothing except depend on fastapi. It was created as a migration path for projects that historically depended on fastapi-slim when that was a separate distribution, but all functionality has since been integrated into fastapi itself. The package is no longer maintained and will receive no updates.

The package's own documentation explicitly warns against installing it and directs users to install fastapi directly instead. It exists solely as a compatibility layer for legacy projects that have not yet updated their dependency declarations.

Use it for:

Updating legacy projects that declared fastapi-slim as a dependency to migrate them to the current fastapi package
Temporary compatibility bridge during a codebase migration from fastapi-slim to fastapi
Understanding why fastapi-slim exists and why it should be removed from your project

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

This package is a deprecated migration shim that depends solely on fastapi; it exists only to redirect old projects and should not be installed.

No. Do not install this package. The package's own documentation explicitly states 'You should not install this package' and directs you to install fastapi instead. It is deprecated, will receive no updates, and serves no purpose except as a migration aid for projects that have not yet updated their dependencies.

Install

fastapi-slim on PyPI

pip

pip install fastapi-slim

uv

uv add fastapi-slim

poetry

poetry add fastapi-slim

Installing fastapi-slim

Before you install

Low install friction, but maintenance status is moot: the package is explicitly deprecated and will receive no further updates. Its only purpose is to redirect old projects to fastapi itself.

License in practice

MIT license permits free use and modification, but this is irrelevant since the package is deprecated and should not be installed.

Quickstart

# Do not use this package.
# Install fastapi instead:
# pip install fastapi

# If you currently have fastapi-slim in your requirements,
# replace it with:
# pip install fastapi

This package is deprecated and should not be installed; use fastapi directly instead.

Verify before relying

Whether any real projects still depend on fastapi-slim and would break if it were removed from PyPI

Package facts

License	MIT (permissive)
Python support	supports the current Python release (>=3.10)
Install friction	low — pure-Python wheel
Runtime dependencies	1 — fastapi
Maintenance	actively maintained — 174 days since the last release
Last repo commit	2026-08-14
First released	2023-12-09
Downloads	83,410/month — #14,077 on PyPI (30-day window, as of 2026-08-14)
Known vulnerabilities	none known (OSV.dev, checked 2026-08-14)

Evidence: fastapi_slim-0.129.1-py3-none-any.whl

Development Status :: 4 - BetaEnvironment :: Web EnvironmentFramework :: AsyncIOFramework :: FastAPIFramework :: PydanticFramework :: Pydantic :: 2Intended Audience :: DevelopersIntended Audience :: Information TechnologyIntended Audience :: System AdministratorsOperating System :: OS IndependentProgramming Language :: PythonProgramming Language :: Python :: 3Programming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Topic :: InternetTopic :: Internet :: WWW/HTTPTopic :: Internet :: WWW/HTTP :: HTTP ServersTopic :: Software DevelopmentTopic :: Software Development :: LibrariesTopic :: Software Development :: Libraries :: Application FrameworksTopic :: Software Development :: Libraries :: Python ModulesTyping :: Typed