pip-auto

Just import it. Missing packages install themselves.

pip install pip-auto

That's the whole setup. From now on, when your code imports something that isn't installed, pip-auto finds the right package on PyPI, installs it on the spot, and your program keeps running — no ModuleNotFoundError, no stopping to run pip install, no restarting.

import pyfiglet               # not installed? fine
from PIL import Image         # import name ≠ package name? fine (installs pillow)
import cv2                    # installs opencv-python
print(pyfiglet.figlet_format("hello"))

[autopip] 'pyfiglet' not found → installing pyfiglet
[autopip] installed pyfiglet==1.0.4 (2.51s)

Why it's nice

• Zero setup. pip install pip-auto turns it on for that Python. pip uninstall pip-auto removes every trace.
• It knows the real package name. PIL → pillow, cv2 → opencv-python, sklearn → scikit-learn, bs4 → beautifulsoup4, google.generativeai → google-generativeai, plus ~1,000 more mappings — and it learns new ones from every wheel it sees. Before installing, it opens the wheel and checks the module is really inside, so a same-named impostor never gets installed.
• Fast. Its own installer (pip is not used): dependencies are prefetched and resolved in parallel, and every file of every wheel is placed in one parallel batch. From the second time on it just hard-links from a local cache. Installing requests + numpy + pandas + flask + rich (22 packages) into a fresh environment: pip 58 s → pip-auto 13 s → 2.7 s the second time. It adds only about 5 ms to Python startup.
• Safe. Names that look like popular packages (typosquats such as requets) and brand-new unknown packages are never installed automatically. If anything fails halfway, everything — including the old versions it replaced — is rolled back.
• Respects "optional" imports. try: import x / except ImportError: in your code, optional imports inside libraries, and importlib.util.find_spec("x") checks are left alone.
• Works everywhere you run Python: scripts, Jupyter / IPython, virtual environments.
• Speaks your language. Messages follow your OS language: English, 日本語, 简体中文, 繁體中文, 한국어, Español, Français, Deutsch, Português, Русский.

Tell it what you want (optional)

# /// script
# dependencies = ["requests<3", "rich"]
# ///
import requests, rich            # a PEP 723 block is installed up front, all at once
import numpy  # autopip: numpy<2   ← pin a version with an end-of-line comment

Commands

AUTOPIP_DISABLE=1 turns it off for a single command.

Settings (autopip config KEY VALUE)

• ask — true to confirm before every install (asks on the console; never installs when nobody can answer)
• safety — strict (default) / warn / off
• link_mode — hardlink (default, fastest) / copy (separate files per environment)
• lang — en, ja, zh, zh-TW, ko, es, fr, de, pt, ru (default: your OS language; also AUTOPIP_LANG)
• index_url / extra_index_urls — other package indexes (pip.ini / PIP_INDEX_URL are read too)

Compatibility

• Python 3.8 – 3.14 (the test suite runs on all seven). Tested mainly on Windows; wheel selection on Linux / macOS is handled by packaging.
• Modules removed from the standard library in Python 3.13 (imghdr, cgi, telnetlib, …) are provided by installing their maintained successors (standard-imghdr, legacy-cgi, …).
• No dependencies. MIT license.

Good to know

• Only packages from PyPI (or the indexes you configure) are installed, and every install is logged.
• In hardlink mode, environments share the same files. If you edit installed files in place, use link_mode copy.

日本語の説明: README.ja.md (included in the source distribution)