Decision simulator — run 5,000 futures on your own figures
Command centre
Type the decision. Get an honest probability. Get scored against reality later.
Decision Radar
Calibration — the honest record
Live proof — computed in this browser just now
Booting the engine…
Why this can’t be faked
Active decisions
Weekly review — ten minutes with your own record
A ritual, not a report: what’s open, what’s due, what still rests on an assumption, and how calibrated the record says you are. Everything below is computed from what this device already holds — nothing is invented, nothing is uploaded.
New decision
Three release-gated domains are live: business runway, career change and major purchase.
Fill the figures below and the engine runs here, continuously.
1 · Frame the decision
Copilot Describe the decision in your own words and let the Copilot fill the form
Prefer to describe it in a conversation? Ask LEXUN is the same three models behind a chat.
What you type here is sent to Anthropic through a LEXUN server function to be read. Your saved decisions and the figures in the form are never sent from this box (the result buttons below a result send a filtered summary, never your figures). Figures the Copilot fills in are ones you wrote — it never adds a number of its own.
Forecasts whether business cash stays above zero over the horizon.
Horizon, reversibility, risk appetite, country and currency
Twelve months is the default because it is the horizon the runway model was built and frozen against. Longer horizons widen the band rather than sharpen it.
This changes what the result is for, not the arithmetic. An irreversible commitment deserves a harder look at the downside than a reversible one.
Recorded with your decision; it does not change the arithmetic. Every released model scores survival against cash staying above zero, and no answer here moves that line — it is kept as context for reading the result back, not as an input to it. The FCA’s Financial Lives 2024 survey is the reference for how thin UK buffers typically are.
Recorded with the decision, and it controls which evidence LEXUN is willing to show you. The released models’ arithmetic does not yet vary by location — that is stated here rather than hidden, and the bundled UK reference figures are withheld for non-UK decisions instead of being passed off as relevant.
Every bundled reference figure is UK: Bank Rate 3.75%, CPI 2.9%, unemployment 4.9% (Bank of England and ONS, as recorded in the world state). Outside the UK the engine still runs, but that context does not apply.
The model is arithmetic on your figures in one currency. LEXUN never converts between currencies and never treats £100,000 and the same number in another currency as equivalent.
2 · Establish reality
Enter each number AND say what kind of information it is. The engine refuses to run on unknowns — it will not invent values.
Import evidence from a CSV — read on this device, never uploaded
A bank or accounting export works. The file is parsed entirely in this browser. LEXUN computes candidate figures from what the file actually contains and shows where each came from — but nothing enters the model until you choose a field, press Use, and classify the value yourself. An imported number is evidence you hold, not a fact LEXUN gets to assume.
3 · Reference class — how often this works out for others
4–5 · Model & simulate
Seeded Monte-Carlo: 5,000 monthly cash paths from your inputs. Same inputs → same result, always. Full methodology.
Explore this result
Three questions the probability cannot answer on its own, each solved by running the same model again on your figures.
The five thousand futures, as they compute
Scenarios
Survival through time, and the tail
What would change my mind
What moves this result (sensitivity)
How much should you trust this number?
What to verify before you decide
What this probability covers — and what it does not
Why this result & what could make it wrong
Challenge — the case against this conclusion
Evidence, assumptions & reference class
Show calculation (reproducibility)
Decision journal — for the person you’ll be when reality answers
Optional, and saved write-once with the forecast. When the outcome lands, future-you learns most from what present-you was actually thinking — not what hindsight rewrites.
Felt confidence is recorded as a word on purpose: a second number would blur with the model’s probability, and they measure different things.
Scenario branches — decide the response before the moment
The engine has already priced four ways this could go. For any of them, you can write the response now — if this happens, I will… — while you are calm and the stakes are still theoretical. Optional, and frozen write-once with the forecast; a plan made before the moment is worth more than one improvised inside it. The four scenarios are predefined stress-test shifts, not historical percentiles — honest tests of your inputs, not forecasts of which path arrives.
Run the analysis first — the branches come from its scenarios.
Before it freezes — the three questions that catch a bad criterion. Open forecasting practice (unambiguous criteria, a named source, edge cases decided in advance) exists because vague forecasts can never be scored. Confirm each:
Saving freezes the forecast. If resolution is at least two weeks away, a halfway review checkpoint is set too — a dated reminder to re-check your inputs against reality. The frozen forecast itself never changes; a material change becomes a new, versioned forecast.
Decision Library
Every saved decision, its frozen forecast, and its status.
Outcomes
Forecasts are only worth anything if you report what actually happened. Resolution criteria were frozen when each forecast was made.
Accuracy
Your calibration record, computed only from outcomes that have actually resolved. Until enough of yours have, there are no numbers here — we don't invent accuracy.
Public methodology
How forecasts are produced, what the known weaknesses are, and how to reproduce any result: LEXUN Accuracy Centre.
Settings
Your plan
Free: the full engine and unlimited decision runs, no card, no account; three saved decisions once checkout opens, and nothing is limited until then. Pro keeps every one.
Appearance
Your LEXUN Key
Changing the passcode re-encrypts your record under the new one straight away. There is still no recovery route, so export a readable copy first if you want a safety net.
Your data
Everything lives in this browser. Export gives you the full auditable graph (decisions, frozen forecasts, outcomes, audit trail) — on every plan, always.
System — governor & platform intelligence
Real health checks and improvement tasks generated from this browser's own usage data. Nothing here is simulated; when there is no data, it says so.
Improvement tasks
Platform memory
Experimental (Labs)
The earlier experimental Labs app has been retired — its concepts could not meet the release gates this platform is held to. What survives lives as staged items on the public roadmap.
Your decision record is locked
A LEXUN Key encrypts everything you decide here so that only you can read it. It is not an account: there is no server holding it, and nobody at LEXUN can open it or reset it. Running a decision does not need one — start one now — but saving it to your record, and everything on this dashboard that reads that record, does. The assistant below needs nothing at all: three messages a day are free.
Not sure what to ask yet? Ask first.
Three messages a day free, no sign-up, no card. It turns a worry into a question this engine can actually score — an outcome, a horizon and a threshold — and then hands you to the engine, which does the arithmetic.
Read this before you type. This is the one feature on LEXUN where your words leave your device: messages you type here are sent to Anthropic through a LEXUN server function to produce the reply. Your saved decisions and results are encrypted here and are never read or transmitted by this box — but anything you type into it is sent, so don't enter passwords, account numbers, health information or other people's personal data. What is sent, and what is kept →
The count is kept in this browser's storage and nowhere else. Clearing your browser data resets it — we are not going to pretend it is a lock. It is there to keep the cost of a free taste bounded, not to trap you.
EXAMPLE — NOT YOUR DATASee a full result, computed here, right now
Computed in this browser just now by the same engine, on a worked example, with a fixed seed. Re-run it yourself and you will get these figures to the digit. Your own record replaces this the moment you unlock it.
Booting the engine…