About zeroleft
zeroleft is a free tool for planning your money around your life instead of the other way round. It takes the ideas in Bill Perkins' Die With Zero — spend on experiences while your health can still carry them, let your net worth peak in mid-life and then draw it down, give while it changes something, insure against a long life rather than hoarding against it — and turns them into a plan you can run on your own numbers.
Who built it
I'm Filip Martinsson — a computer science engineer, and an entrepreneur and investor.
I built zeroleft for myself. I read Die With Zero, agreed with most of it, and then found there was no straightforward way to actually apply it: to work out how much I could spend each year and still land near zero, to place the trips and the time with friends and family in the years I'll be well enough to enjoy them, and to check that a long life or a bad decade in the markets wouldn't derail it. The arithmetic is tedious and easy to get wrong by hand. So I wrote the tool I wanted.
It turned out to be useful enough that I think other people planning the same trade-offs can get something out of it. That's the only reason it's public.
What it is, and what it isn't
zeroleft is a planning aid, not financial advice. It has no tax model, it makes no return guarantees, and it can't know your circumstances. Use it to see the shape of a plan and to notice when you're quietly over-saving — not as a withdrawal strategy.
It's built on the book's ideas but is not affiliated with or endorsed by Bill Perkins or the publisher.
Your data
The projections run entirely in your browser — nothing is sent anywhere to be calculated. Plans are stored per account on a small server with a Postgres database in the EU, and you can export or import any plan as JSON at any time. Sign-in is email and password only: no third-party login, and traffic is measured with a self-hosted, cookieless analytics tool — no cookies, no personal data, nothing handed to a third party.
Money
zeroleft is free. There are no ads, and nothing is sold.
Contact
The best way to reach me is on X or LinkedIn. I read what people send about the tool — bugs, disagreements with the model, and questions all welcome.