For people who ask "but what if…"

Every What-If,
answered.

What-If you got that promotion? What-If you financed that car? What-If you waited two years and paid cash? What-If you won that Bat'leth tournament on Kaylon 5? What-If you YOLO'd your savings into meme stocks and Pokémon cards?

Mycroft can't tell you what to do.
But he can tell you what will happen if you do.

Get What-If Weaver $29 Windows · One-time · No subscription
Local-first · No cloud
Not AI
$29 · One-time
What-If Weaver · ✨ Weave · Alex — Full Life Arc
What-If Weaver Weave view — four 40-year projection scenarios overlaid on one chart

Under the hood

Two engines.

One projects what's known. The other models what isn't.

Deterministic

Mycroft

The projection engine.

A discrete-time, vector-state simulation engine that routes chronological cash flows through prioritized liquidity waterfalls — charting a household's multi-decade trajectory toward either compound accumulation or cascading financial ruin.

Stochastic

Catapult

The event engine.

A stochastic event-generating engine that simulates pseudo-random financial volatility.

How it works

Your finances.
Every possibility.

Every angle on your financial life — and every branching future you can imagine.

🟡

IRL

What if you'd done it differently?

Start with your actual financial life — accounts, income, expenses, debts. Your IRL baseline is the gold line: where you actually are, not where you hope to be. Everything else branches from here.

🔀

What-Ifs

Branch any decision, compare all futures

Create parallel scenarios from your IRL baseline. Retire at 45 or 67. Buy the house or keep renting. Take the promotion or start the business. See the dollar difference, across decades, on one chart.

🌪

Plot Twists

Model the curveballs.

Raises, layoffs, kids, mortgages, divorces, retirements. Every life event is a plot twist that shifts the trajectory. Add them to any scenario and watch the ripple propagate across decades.

🎯

Catapult

Pressure-test the plan.

The stochastic event engine throws unexpected life events at any scenario — job losses, market shocks, surprise expenses. You see whether the plan still holds.

📈

Weave

The future is fuzzy. Embrace it.

Mycroft runs 500 simulations on every projection, modeling the range of likely outcomes — not just the rosy one. Volatility drag included. (Yes, that's real.) All futures on one chart.

✨

Dreams

63 milestones across five tiers

Lived the Dream rewards real IRL progress. Weaver Dreams rewards planning depth. From Daydreamer to Legend. No confetti for doing nothing.

🔒

Local-First

Your numbers stay yours.

Everything runs on your machine. No cloud sync, no account required, no telemetry. The only thing that leaves your device is your license activation — a brief handshake, nothing more.

📄

Export

Show your work.

Export a polished PDF report for your spouse, your advisor, or yourself in five years when you've forgotten the math. Pop the chart to a second monitor for Zoom calls. Mycroft signs every page.

The Engine Has a Name

His name is Mycroft.
He's not AI.

He doesn't connect to the internet. He doesn't call home. All the math — every simulation, every projection, every sensitivity analysis — runs on your machine, with your numbers, in private.

What Mycroft does, very well, is take those numbers and tell you where they go. Five years. Ten years. Forty. Every assumption visible. Every result auditable. No cloud, no accounts, no "just trust the algorithm."

Mycroft notices when your credit cards grow faster than your income. He notices when your savings rate won't get you to retirement on time. He notices when cash has been sitting idle long enough to cost you something. He notices when a spending habit is quietly doing more damage than it looks like on any given month.

He doesn't judge any of it. But he notices.

Mycroft Engine · TANSTAAFL Labs · Computed locally on your machine

How it works

From your numbers
to every future.

Four steps to a financial picture you can interrogate — and a stochastic engine for the futures you didn't see coming.

01

Build your IRL.

Load your accounts and cash flow. Mycroft starts where you actually are — not where you hope to be.

02

Add the life events you know.

College, the next car, a planned retirement. The known plot points of the next decade — placed on the timeline at the years you expect them.

03

Let Mycroft project your future.

Forty years of trajectory. Every assumption visible. Every result auditable. No cloud, no advisor, no "trust the algorithm."

04

Ask 1,000 What-Ifs.

Branch any decision. Mycroft replays forty years for each path and plots them side by side on one chart. Then ask again. And again.

And when you want to break it

Catapult — the stochastic event engine.

When you want to pressure-test a future, Catapult throws unexpected life events at it — job losses, market shocks, surprise expenses — until you see whether the plan still holds.

Inside the app

The interface,
frame by frame.

Scroll the strip. Click any frame to enlarge.

Accounts setup screen for building your real-life baseline
Add your accounts to build your IRL.
Income and expense modeling interface
Model your income and expenses.
Life event entry showing known plot points placed on the timeline
Add the life events you already know. Speculate on the rest later.
Detailed income and investment scenario configuration
Details matter — model complex income and investment scenarios easily.
Multi-decade financial projection chart
See your financial future.
Multiple What-If scenarios plotted side by side
Compare as many What-Ifs as you want.
Per-scenario model parameter tweaks panel
Per-scenario model tweaks.
Debt-free date projection visualization
Find your debt-free day.
Catapult stochastic event engine pressure-testing interface
Catapult — pressure-test any future.
Live IRL update propagating through all projections
Update your IRL anytime. Watch it ripple through every projection.
Professional PDF report export preview
Generate and export professional reports.
Multiple pop-out windows across monitors
Pop out as many windows as you need.

What it shows you

The math,
on screen.

Six examples of what Mycroft surfaces once your numbers are in.

Dashboard with a red Credit Card Debt Spirals Detected warning box click to enlarge

📊 Dashboard · Proactive debt warnings

He flagged it in red. He was polite about it.

When credit card balances start growing faster than income, Mycroft puts a red box on the Dashboard the moment you open the app. He prints his usual notice underneath: "Mycroft notices. He doesn't judge. But he notices."

Weave chart showing IRL trending toward negative net worth for a couple making quarterly Disney trips click to enlarge

✨ Weave · Recovery scenarios

When IRL trends the wrong way, the alternatives become obvious.

Plot two or three recovery paths against a baseline that's heading negative. Watch the dollar gap widen across the five-year horizon. The intervention scenario isn't always the obvious one — but it's always plotted, with the end-of-period numbers right underneath.

Weave chart showing IRL trending to negative 807K versus two recovery scenarios click to enlarge

✨ Weave · Category-level analysis

Find the category that's quietly eating your future.

Trace a million-dollar trajectory difference back to a single spending bucket. The IRL line slumps to negative; one habit change recovers six figures; a full audit recovers seven. Same income, different choices, all plotted side by side.

Detailed What-Ifs and Plot Twists panel for a high-income couple with multiple car payments and lease ends click to enlarge

🔀 Plot Twists · Long-form decision modeling

Make the pattern visible.

Map ten or twenty Plot Twists across a decade — promotions, leases, loans, payoffs, raises — and the rhythm hiding inside high income and low savings becomes obvious. Slide the right-hand parameters and the entire projection re-flows.

Purple themed Weave chart comparing minimum credit card payments versus aggressively paying off the card click to enlarge

✨ Weave · 5-year horizon

Pause investing to kill the card, or keep going?

Two lines. One honest answer. Mycroft ran both — Minimum Payments ends at $64K, Nuke the Card ends at $66K — and the gap is smaller than you'd think. It's not always obvious which one wins, which is exactly the point.

Weave chart modeling a scenario where market returns are flat for two decades click to enlarge

✨ Weave · Worst-case modeling

What if the market does nothing for twenty years?

Mycroft has thoughts. They are not optimistic. Drop the return assumption to zero, hold inflation steady, and watch the lines flatten. It's the question every honest planner asks and almost no plan answers. Now it does.

Pricing

Own it forever.

What-If Weaver · Full License

$29

One-time · Windows · License key via email

TANSTAAFL — There Ain't No Such Thing As A Free Lunch, except for the updates, which are.

  • The full workflow — nothing locked behind upgrades
  • Unlimited What-If scenarios and Plot Twists
  • 12 bundled example files to help you get started
  • 63 Dreams achievements across five tiers
  • PDF report export and multi-monitor presenter mode
  • Free updates
  • Export & import your data (.whatifweaver format)
  • License activates on one Windows machine
Buy Now — $29

30-day money-back guarantee · Cancel via email

Secure checkout via LemonSqueezy · Instant license key delivery

Questions

Before you buy

Mycroft is the projection engine inside What-If Weaver. He runs entirely on your machine — no internet connection required, no data leaving your device. He runs 500 Monte Carlo simulations on every projection, signs every PDF report, and notices things in your numbers that are easy to miss when you're living inside them. He's named after a supercomputer, which felt appropriate.
No. What-If Weaver is a one-time purchase. You pay once and own it permanently, including all future updates within v1. No subscription, no renewal, no monthly fee, no "we're raising prices" email in year two.
Currently Windows only. What-If Weaver is a native desktop app — it runs entirely on your machine with no browser or web app required. No internet needed after activation.
Entirely on your machine. No cloud, no servers, no accounts required. All your numbers stay local. You can export everything to a .whatifweaver file anytime for backups or to move to a new machine.
After purchase you receive a license key by email. Enter it on first launch to unlock the app on your Windows machine. Moving to a new PC? Use the Deactivate License button in the Settings tab — it frees the license immediately so you can activate on any new machine yourself.
No — and it's not trying to. What-If Weaver is a personal modeling tool for comparing scenarios. It produces projections and simulations, not personalized financial advice. What-If Weaver does the math. Your advisor does the judgment. Use both.
Only for initial license activation and a brief background validation about once per month. The app itself — projections, charts, scenarios, everything — runs fully offline.
30-day money-back guarantee. If What-If Weaver isn't what you expected, email hello@whatifweaver.com within 30 days for a full refund.

Stop wondering.
Start weaving.

Get What-If Weaver $29

Windows · One-time purchase · Yours forever