Start with the free web app if you want proof first, including the federal retirement sample for FERS-style planning. Buy Pro when you want the full planner, saved scenarios, exports, and desktop access in one one-time purchase.
You do not need to make a pricing decision before seeing the planner work. Open the free web app, test the workflow, or start with the federal sample plan, then come back here if you want the complete planner and desktop bundle.
No account required · No credit card
The web app runs Python in your browser via Pyodide — no server, no data sent anywhere. Try all the modules with one scenario before you decide.
Federal retirement fit: start with a federal sample plan and light pension / supplement inputs in the web app before deciding if you want the full workflow.
Founding Member price · Increases to $249 at 200 users · One-time · Yours forever
Price increases to $249 after 200 Founding Members
Founding Member pricing
One license key unlocks the Windows desktop app, Linux AppImage, and the full web app. Use whichever fits the moment. Your data is always yours.
Buy if you want unlimited scenarios, saved plans, exports, deeper Monte Carlo testing, and full federal editing with advanced controls.
Price increases to $249 after 200 Founding Members
Secure Stripe checkout | 30-day refund policy | Direct email support
How much can I convert each year without creating a worse tax or IRMAA outcome later?
What changes if I retire at 60, 62, 65, or phase out of work gradually instead?
Does this plan still work under weaker markets, higher spending, or future tax-law changes?
Can I export something clear enough to review with my spouse, CPA, or advisor?
Want to see how the output looks? View screenshots or read the comparison page before you buy.
| Feature | Free Trial | Pro — $149 |
|---|---|---|
| Core Planning | ||
| All planning modules | ✓ | ✓ |
| Scenarios | 1 scenario | Unlimited |
| Planning horizon | Up to 20 years | Up to 100 years |
| Save & load plans | — | ✓ |
| Federal retirement sample + light inputs | ✓ | ✓ |
| Full federal editing + advanced controls | — | ✓ |
| Tax & Roth Modeling | ||
| Basic tax projections | ✓ | ✓ |
| IRMAA threshold modeling | ✓ | ✓ |
| Roth conversion modeling | ✓ | ✓ |
| Advanced Roth optimizer | — | ✓ |
| Editable tax parameters | — | ✓ |
| State tax modeling | — | ✓ |
| Monte Carlo & Stress Testing | ||
| Monte Carlo simulations | 500 runs | Unlimited |
| Market environments | 1 (GBM baseline) | All 7 |
| Breakpoint analysis | — | ✓ |
| Sensitivity analysis | — | ✓ |
| Safe withdrawal rate analyzer | — | ✓ |
| Visualization & Export | ||
| Sankey cash flow diagrams | — | ✓ |
| Interactive goal solver | — | ✓ |
| PDF report export | — | ✓ |
| Excel export | — | ✓ |
| Export / import plan as JSON | ✓ | ✓ |
| Encrypted cloud sync (optional) | — | ✓ |
| Estate & Legacy | ||
| Estate value projections | — | ✓ |
| Legacy goal tracking | — | ✓ |
| Inherited IRA RMD analysis | — | ✓ |
| Estate tax exposure tracking | — | ✓ |
| Platform | ||
| Web app (browser, any device) | ✓ | ✓ |
| Windows desktop app | — | ✓ |
| Linux AppImage | — | ✓ |
| Offline use | — | ✓ (desktop) |
| Data stays on your device by default | ✓ | ✓ |
| Optional cloud sync (end-to-end encrypted) | — | ✓ |
| All future updates | — | ✓ Free forever |
| Software | Year 1 | Year 3 | Year 5 | Year 10 |
|---|---|---|---|---|
| Fatboy — Founding Member | $149 | $149 | $149 | $149 |
| Fatboy — Regular | $249 | $249 | $249 | $249 |
| Boldin ($12/mo) | $144 | $432 | $720 | $1,440 |
| ProjectionLab ($109/yr) | $109 | $327 | $545 | $1,090 |
| Advisor fee (1% on $1M) | $10,000 | $30,000 | $50,000 | $100,000 |
When you buy Pro, you get a single license key. Enter it in the desktop app during installation, and enter the same key in the web app to unlock full access. One purchase, one key, both products.
Not by default. The web app runs Python locally in your browser using Pyodide — there's no server receiving your numbers. The only automatic network call is license key validation. Pro users can optionally enable cloud sync to back up and move plans across devices — but the plan is encrypted in your browser using your license key before it's uploaded. We receive ciphertext we cannot read. If you never use cloud sync, no financial data ever leaves your device. Full technical details →
$149 is locked in for the first 200 users. Once we hit 200 Founding Members, the price will increase. If you're reading this, it's still available. Founding Members get all future updates free, forever.
Yes — the free web app trial lets you use all the modules with one scenario, no account required. That's the best way to see if the depth and interface fit how you think about planning. When you're ready to save scenarios, export, and use the desktop, buy Pro.
The web app works in any modern browser on any device — Mac, iPad, Windows, Linux, Android. The desktop app is available for Windows 10/11 and Linux (AppImage). macOS desktop is on the roadmap.
That's exactly what Fatboy is built for. You can edit federal and state tax parameters yourself — no waiting for a vendor update. When OBBBA passed in 2025, Fatboy users were updated in minutes. All updates are free for Pro users.
Yes. Pro includes PDF and Excel export, so you can generate professional-quality reports to review with a spouse, share with a CPA or tax advisor, or document your strategy for annual review.
Checkout runs through Stripe. Then you get a receipt, your license key by email, download links for the desktop app, and immediate access to unlock Pro features in the web app.
Credit cards and PayPal through Stripe. Secure checkout, nothing stored on our end.
Email us within 30 days and we will make it right. If Fatboy is not the right tool for how you plan, we do not want you stuck with it.
Best for people who want unlimited scenarios, exports, saved plans, and a tool they can keep using year after year.
Start free in the web app first, or lock in Founding Member pricing for the complete planner, desktop app, and all future updates in one one-time purchase.
Founding Member price · Increases to $249 at 200 users · Desktop + Web included · All future updates free