# Npb: Nixpkgs PR build diff CLI inspired by nixpkgs-review

DevFeed: [Npb: Nixpkgs PR build diff CLI inspired by nixpkgs-review](<https://devfeed.tech/articles/npb-nixpkgs-pr-build-diff-cli-inspired-by-nixpkgs-review-31361.md>)

Original publisher: [Read original article](<https://discourse.nixos.org/t/npb-nixpkgs-pr-build-diff-cli-inspired-by-nixpkgs-review/79106>)

Author: samestep

Published: 2026-07-21T21:09:29Z

Content type: article

Language: en

Sources: [Announcements - NixOS Discourse](<https://devfeed.tech/sources/announcements-nixos-discourse.md>)

Topics: [Nix](<https://devfeed.tech/topics/nix.md>), [Development](<https://devfeed.tech/topics/development.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>)

Tags: [announcements](<https://devfeed.tech/tags/announcements.md>), [caching](<https://devfeed.tech/tags/caching.md>), [cli](<https://devfeed.tech/tags/cli.md>), [memory](<https://devfeed.tech/tags/memory.md>), [parallelism](<https://devfeed.tech/tags/parallelism.md>), [text](<https://devfeed.tech/tags/text.md>)

## AI overview

A developer introduces npb, a Nixpkgs pull-request build outcome diff CLI inspired by nixpkgs-review. It compares build results before and after a change, and adds features including passthru.test inclusion, cached failures, lower memory usage, parallel Nix evaluations, reproducible report commands, and progress indicators.

## Source excerpt

Hello! While reviewing Nixpkgs PRs written by myself and others, I've found it difficult to keep track of which build failures were preexisting and which are regressions introduced by the PR itself. So I built a tool called npb which produces reports that are similar to nixpkgs-review, but show both before and after, instead of just after. github.com GitHub - samestep/npb: Nixpkgs build outcome diff CLI Nixpkgs build outcome diff CLI While building this, I also included some other features I had found myself wanting previously, such as: automatically including passthru.tests caching build failures in a local database reducing memory usage of Nix evaluations speeding up Nix evaluations via parallelism giving each report a command that reproduces the same report providing progress indicators during long-running operations I hope you find it useful! Disclosure, quoting the project's README: The development of this project was AI-assisted. There is no AI-generated text in this README, npb --help, or npb's generated reports. 7 posts - 4 participants Read full topic