Why
Every payday I move money into a few different accounts. The percentages stay the same and only the size of the pay changes, so I was doing the same arithmetic in a calculator app every week and then typing the results into my bank.
What it does
Enter your pay, then set up categories such as Savings, Rent and Spending. One bar shows the whole split. Drag the dividers to change the percentages, or type an exact figure into a category if you want a specific number. Each category shows its dollar amount next to a copy button, which puts the bare figure on your clipboard so it pastes straight into your bank app.
Your split is saved in the browser and is still there next payday. A share link passes your categories and percentages to someone else, without your pay amount. It covers eight currencies and has a dark mode.