Independent product
TenthKeep
Opens the live site in a new tab
A private budget, debt and net-worth workspace that runs in your browser: what you can spend until payday, a tenth kept first, and every formula shown. Free to use, no bank login.
A money workspace that lives in your browser, starts from one honest number and keeps a tenth of what you earn aside before anything else.
What it does
TenthKeep is a private budget, debt and net-worth workspace that runs in your browser. Nothing is held on a server unless you choose to share it, and there is no bank login. It opens on one question: what can I spend until payday? It takes your balance, takes off the bills still to come and the amount you chose to keep, and shows what is left, with the working open to read.
Around that number sit the parts a month needs: a budget with a limit per category, goals with a pace, a pay split that sets the tenth aside first, a thirteen-week cash forecast shown as a range, a debt-free date that compares paying the highest rate first with the smallest balance first, and a net-worth view built only from readings you recorded. Freelancers get a business view with invoices, VAT to set aside and a tax and contribution reserve. A demo opens with nine months of invented activity, so you can use it before you give it anything of yours. The core app is free. Paid plans for sync and sharing are not on sale yet.
Why I built it
It began as a single-file budget tracker built around the principles in The Richest Man in Babylon, above all the old advice to keep a tenth of everything you earn. It was meant to be my own money tool, simple enough to share and to sell. That first version was rebuilt as a proper web app and renamed TenthKeep, after the tenth.
What I learned
A money tool that shows a wrong number is worse than one that shows none, so most of the work went into checking arithmetic by running it rather than reading it. A zero that quietly switched which balance was used, a month counted before it had finished, a refusal printed as a figure: these survived reading and only showed up when the code was executed. The product also says what it will not do. It plots no history you did not record, it draws no probability it has not calculated, and it labels example figures as examples.
The design lesson was the same. People came away from the first version of the app confused, so the next version kept every feature and changed the order, adding an always-available guide. Less hidden, not less there.
