US payroll taxes look simple until you try to code them. Federal brackets are the easy part. Then you meet 50 states, plus DC, that each do something slightly different. Alabama lets you deduct the federal tax you paid. Pennsylvania taxes your 401(k) contributions. Ohio adds a fixed dollar amount once you pass a threshold. Utah gives a credit that shrinks as your income rises.

I wanted a free take-home pay calculator that handles all of that, shows its working, and loads fast. The result is NetPayMeter . This post covers how it's built: one tax engine, state rules as data, server-rendered results, and an embeddable widget.

The stack

Laravel 12 on PHP 8.3

No database. Every tax rule lives in PHP config files, and page copy lives in Markdown files.

Plain JavaScript for the front end, with no framework and no build step.

GitHub Actions runs the tests, builds a release tarball, and deploys it to a small VPS over SSH.

Skipping the database was the best decision in the project.…