What's new in pip 26.1 - lockfiles and dependency cooldowns!

28th April 2026 - Link Blog

What's new in pip 26.1 - lockfiles and dependency cooldowns! (via) Richard Si describes an excellent set of upgrades to Python's default pip

tool for installing dependencies.

This version drops support for Python 3.9 - fair enough, since it's been EOL since October. macOS still ships with python3

as a default Python 3.9, so I tried out the new Python version against Python 3.14 like this:

uv python install 3.14

mkdir /tmp/experiment

cd /tmp/experiment

python3.14 -m venv venv

source venv/bin/activate

pip install -U pip

pip --version

This confirmed I had pip 26.1

- then I tried out the new lock files:

pip lock datasette llm

This installs Datasette and LLM and all of their dependencies and writes the whole lot to a 519 line pylock.toml

file - here's the result.

The new release also supports dependency cooldowns, discussed here previously, via the new --uploaded-prior-to PXD

option where X is a number of days. The format is P-number-of-days-D

, following ISO duration format but only supporting days.

I shipped a new release of LLM, version 0.31, three days ago. Here's how to use the new --uploaded-prior-to P4D

option to ask for a version that is at least 4 days old.

pip install llm --uploaded-prior-to P4D

venv/bin/llm --version

This gave me version 0.30.

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