I got tired of retirement calculators that either assume one fixed return forever, or run Monte Carlo by pulling each year independently out of a bell curve. Real markets don't behave like that. Bad years cluster, and a crash in your first three years of retirement is a completely different problem from the same crash at 85.

So this one samples multi-year blocks out of actual history instead: 25 countries, 1900 to 2025, reassembled into thousands of possible futures. It's a stationary block bootstrap, which is the standard approach in the lifecycle-investing literature. When a plan fails it tells you which way it failed, whether that was weak growth, bad sequencing, or inflation at the wrong moment.

Canada and the US have full tax and benefit modelling (RRSP/TFSA and CPP/OAS on one side, 401(k)/IRA and Social Security on the other). Everywhere else you get a pre-tax projection. If you're in the EU or UK you can run the Quick Check, but you can't sign up yet, because I haven't finished the compliance work.

There's no account linking, and the Quick Check needs no signup at all. The methodology is written up at /methodology. It's an educational tool, not financial advice.

It's free right now. Paid plans come later, and there's a founding rate if you want to lock one in early: $50/year for as long as you stay subscribed, first 50 people. https://buy.stripe.com/14A7sN6Gycny54rdXv5Rm01 Nothing is gated behind it today.