Retirement planning,
fully simulated.

Killion links your real accounts and runs 1,000 market lifetimes across your whole plan: Monte Carlo projections, backtesting to 1928, and an AI assistant that can see your numbers.

Start a 5-day free trial See pricing
Killion app dashboard

Link the brokerages you actually own.

More than $180M in assets connected across 15+ brokerages and crypto exchanges.

Plug in once. We do the rest.

Killion links to every brokerage and crypto exchange through SnapTrade: read-only, in under three minutes. Every recommendation runs against the holdings you actually have, not the ones you remember.

  • Read-only by design
    We can see your positions. We cannot trade, transfer, or withdraw a dollar.
  • Always in sync
    Schwab, Fidelity, Robinhood, IBKR, Coinbase: kept fresh automatically.
  • Two-minute setup
    One sign-in via SnapTrade. No spreadsheets after that.
Connect your accounts See supported brokerages
Powered by SnapTrade: read-only access.

Run a 1,000-path Monte Carlo simulation.

See decades, not weeks.

Killion runs a thousand probabilistic simulations against your actual portfolio to project net worth, retirement runway, and FI date across the next sixty years. Adjust contributions, returns, or inflation and watch the cone of outcomes shift in real time.

  • 1,000-path Monte Carlo
    Median, best 10%, and worst 10% projected across decades.
  • Adjust any assumption
    Returns, contributions, inflation, retirement age: instant feedback.
  • Stress-test reality
    Model recessions, layoffs, or big purchases. See if your plan still holds.
Start a 5-day free trial How Killion works
Built for long-term planning. First plan includes a 5-day free trial.

Designed for complex incomes.

FIRE planners.

For anyone running the numbers on financial independence, modeling decades of returns to set a real FI date.

Read-only access, private by default.

A tool that respects your money.

Killion is a planning tool, not an advisor. We don't trade for you, take commissions, or sell your data, and account access is read-only by design.

  • No commissions, no kickbacks
    We charge a flat subscription. We never get paid by funds, brokers, or advisors.
  • Your data isn't for sale
    No ads, no data brokers. We do not sell any of your financial data. Website analytics measure this site only, never your accounts or transactions. Your subscription is how we pay the bills.
  • Encrypted end to end
    Encrypted in transit and at rest, with credentials never stored by us.
How your data is handled About read-only linking

What we have not done yet.

SOC 2 Type II certification is on our roadmap and has not been completed, and we have not commissioned a third-party security audit. We would rather say that than imply an audit we have not passed. The full security position.

Original research, not recycled advice.

We run the simulations ourselves and publish what came out, including when the result is inconvenient.

Vanguard dynamic spending vs the 4% rule: what the spending actually looks like

Vanguard dynamic spending vs the 4% rule on 5,000 paired retirements: +$17,834 lifetime spending in the median world, -$198,351 in the worst tenth. Q1-Q4 run.

Retirement withdrawals

Monte Carlo retirement planning: what 1,000 lifetimes show that one projection hides

Monte Carlo retirement planning on one frozen retiree: real p50 $1.08M, p10 $0, p90 $5.69M at year 30, 10.4% ruin, versus a 7% deterministic path. 1,000 paths, seed 20260622.

Monte Carlo & projections

Why 90% chance of success is the right goal and 100% is a trap

90% chance of success vs 100%: rigid 3.95% hits 90% on 1,000 paths. 2% still only 99.4%. 100% is not on the grid.

Monte Carlo & projections
The retirement planning guide All research

Frequently asked questions

What is Killion?
Killion is retirement and financial planning software you use yourself. It links your brokerage and crypto accounts read-only, runs 1,000-path Monte Carlo simulations against your real holdings, backtests your plan against every market since 1928, and lets you explore decisions with an AI assistant that can see your numbers.
Is Killion a financial advisor?
No. Killion is software, not a service. We are not a registered investment adviser or broker-dealer. We do not recommend specific securities, manage assets, or trade on your behalf, and account access is read-only so we could not trade even if asked.
How is my data protected?
Account connections go through SnapTrade in read-only mode: Killion can see positions and transactions and is technically incapable of trading, transferring or withdrawing. You authenticate at your brokerage, so Killion never receives your credentials. Data is encrypted in transit and at rest. SOC 2 Type II certification is on our roadmap and has not been completed.
How accurate are the simulations?
Killion runs 1,000-path Monte Carlo simulations using a five-regime market model, so downturns cluster the way they historically have rather than being drawn independently each year. Runs are seeded and reproduce exactly. Markets remain unpredictable, so treat the output as a range of outcomes to plan against, not a forecast.
Who is Killion built for?
Anyone juggling multiple accounts, equity compensation, irregular income or a long-term plan. We see strong fit with FIRE planners, tech employees, doctors, lawyers and freelancers, but no finance background is required.
How does account linking work?
Through SnapTrade, the account-linking layer used by a range of fintech products. You sign in to each brokerage or crypto exchange once through SnapTrade. Killion never sees your credentials and access stays read-only. You can revoke it from Killion or from your brokerage at any time.
Where can I use Killion?
Killion runs in the browser on desktops, laptops, tablets and phones. Since v1.7.0 the dashboard, finances, budget, projections and backtesting are all laid out for small screens.
How does Killion compare to hiring a financial advisor?
An advisor manages your money, typically charging around 1% of assets a year — roughly $7,500 annually on a $750,000 portfolio, rising as the balance grows. Killion is software you use yourself for a flat monthly subscription, and takes no commissions or kickbacks. An advisor also does things Killion does not, including tax planning and behavioral coaching.
Does Killion model taxes or Roth conversions?
No. Projections are pre-tax and there is no Roth conversion, RMD or IRMAA modeling. If tax sequencing is your main question, Boldin is a better tool for it and we say so on our comparison page.
Can I try Killion before paying?
Yes. The first plan includes a 5-day free trial of the full product. A card is required; you are not charged until the trial ends. Paid plans also carry a 14-day refund window.