Poetry and uv are both Python package managers built to solve the same problem, which is making sure every machine installs exactly the same dependencies. Here’s how the two compare on speed, lockfiles, and day-to-day workflow, and why I now point teams to uv.

On a Monday morning, Ada clones a Python project, runs the install command, and the tests pass. On Thursday, Sam clones the exact same commit, runs the exact same command, and three tests fail.

Nobody changed a line of code between Monday and Thursday. What changed was the outside world, as somewhere in the project’s dependency tree, unknowingly, a library the project uses had shipped a new minor version on Wednesday night. Ada got the old one while Sam got the new one. The project said “ any version above 2.0 is fine ”, and both of them were technically right.

Every Python developer, to be honest, every developer has lived some version of this.…