A calm, focused way to understand your net worth, your spending, and your future — built for people who want to see clearly without handing their data to anyone.
Privacy
Vault works two ways, and both are completely private. Keep everything in your browser — nothing leaves your device, no account required, no trackers, no analytics on your spending. Or sign in with your Google account to access Vault across every device, secured by top-level encryption on the Sui blockchain. Either way, only you can read your data.
Features
Four tools, each designed to do one thing well, working together to give you a single clear picture.
Every account, every asset, every liability — in one place. See what you own, what you owe, and how that number is moving over time.
Understand where your money actually goes. Categorise transactions, spot patterns, and stop being surprised by the end of the month.
Project forward. Model what your savings, investments, and property could look like in five, ten, twenty years — with assumptions you can adjust.
Know what you'll owe before HMRC does. Estimate your income tax, dividend tax, capital gains, and ISA headroom in plain English.
Free tools
A growing set of focused calculators and planners — free, private, no data collected, built for UK users. Real financial education shouldn't sit behind a paywall.
Get started
No sign-up, no onboarding flow, no credit card. You open Vault and you start.
Launch it in your browser. There's nothing to install and nothing to create — your session begins the moment the page loads.
Bank accounts, ISAs, pensions, property, loans. Enter the balances once. It takes a few minutes, and then it's done.
Your net worth, your spending, your plan, your tax — all live, all in one view. Come back whenever you want to update it.
Two ways to use Vault. Stay in your browser and nothing ever leaves your device. Or sign in with your Google account to access Vault on every device, secured by top-level encryption on the Sui blockchain. Both are private. Both are free.
Built for the UK
Most finance apps are built for somewhere else. Vault is built for here — with the rules, allowances, and accounts that actually matter to your money.
Pricing
Vault is free today. Vault will be free tomorrow. If it ever changes, the version you have will keep working — no subscriptions, no expiring access, no ads, no upsell. The tools you need to understand your own money should not sit behind a paywall.
I built Vault because I wanted a tool that did what I needed — and I couldn't find one. Every finance app I tried either asked for my bank login, sold my data, locked the useful features behind a subscription, or was built for somewhere that wasn't the UK.
So I made something quiet. Something that lives on your device, that shows you what you have and where it's going, and that doesn't try to be anything else. If it's useful to you too, that's the whole point.
— Jonty, builder of Vault.
A weekly letter on personal finance, UK-specific money thinking, and the ideas behind Vault. Free, no spam, unsubscribe any time.
Prefer to read first? Read Reasonable Money on Substack →
Found a bug, have an idea, or just want to say hello? I read everything that comes in.
FAQ
Everything you need to know about Vault — what it is, how it handles your data, what's coming next, and how to help spread the word.
Vault is a private personal finance tool built for the UK. It runs entirely in your browser and tracks your net worth, spending, financial planning, and tax in one calm, focused interface — without ever asking you to connect a bank account, sign up, or hand over any data.
If you've ever wanted a finance app that just shows you what you have and where it's going, that's Vault.
By default, everything you enter into Vault is stored in your browser's local storage on your own device. There's no account, no cloud sync you didn't ask for, no analytics on your spending, and no third-party trackers. If you close the tab, your data stays on your machine.
If you want it across devices, you can opt in to cryptographically secured backup on Walrus, a decentralised storage network anchored on the Sui blockchain. Your data is encrypted in your browser before it ever leaves the device. The encryption key is derived from your sign-in and never leaves your session — meaning Vault can't read your data, the Walrus storage nodes can't read your data, and no third party can. Only you can.
If you'd rather not sign in, Vault still works fully locally — that's the default. Clear your browser data without exporting a backup and it's gone; there's nothing on our side to restore from, because we never had it. That's the trade-off, and it's deliberate.
Sign in with Google through Sui's zkLogin — a zero-knowledge proof system that derives a Sui blockchain address from your Google identity without ever revealing it on-chain. No password, no seed phrase, no wallet to manage. The browser keeps an ephemeral key for the session; that key is what decrypts your data.
Once signed in, Vault encrypts your data in your browser and stores a cryptographically secured copy on Walrus, the decentralised storage network built on Sui. Each snapshot is content-addressed by its cryptographic hash, tied to your Sui address, and distributed across many independent storage nodes — none of which can read it. When you sign in from another device, Vault verifies your zkLogin, fetches the blob, and decrypts it locally. Same data, same privacy, anywhere you sign in.
Vault sponsors the gas and storage costs through a Cloudflare worker — you don't need SUI tokens, you don't need a wallet, and you don't pay any chain fees. It stays free.
An encrypted snapshot does — but only when you sign in, and only to a decentralised storage network where no single party can read it. The encryption happens in your browser before anything is sent; the key is derived from your zkLogin session and never leaves your machine. Vault can't read your data, the storage nodes can't read your data, and no company database holds it.
That's the part that makes this different from "cloud sync" in a traditional finance app. There's no central server that can be coerced, breached, or paywalled into accessing your finances. The blockchain backbone (Sui) and the storage layer (Walrus) are public infrastructure, not Vault's servers — meaning there's nothing for an attacker to attack and nothing for a business to sell.
Sign-in is opt-in and reversible at any time. By default, Vault still works fully locally — that hasn't changed.
Vault is delivered as a single web page — open it in your browser and you're always on the latest version. New features and improvements ship as silent updates; the next time you visit, the new version is already live.
Because nothing about your data lives on a server, you don't need to migrate or sync anything when versions change. Your local data carries through.
Real financial education and clarity should not sit behind a paywall, and your financial data should not be the price of admission to using a tool. The mission is to give people a calm, clear, fully private way to understand their own money — without bank logins, without subscriptions, and without selling anyone's data.
The thinking behind it goes deeper in Reasonable Money, the weekly letter that sits alongside the app.
Vault is free today and will be free tomorrow. Personal finance tools are commodity software at this point — the value isn't in the calculations, it's in being able to use them privately and on your terms. Charging for that would defeat the point.
If anything ever changes about pricing, the version of Vault you have on your machine will keep working. There are no subscriptions, no expiring access, no upsells.
A few things make Vault unusual:
Cryptographically secured backup on Sui & Walrus. An optional one-tap sign-in encrypts your data in your browser and stores it on a decentralised storage network — no central server, no company database, no one but you with the key. Vault sponsors the gas and storage, so it stays free. No other UK personal finance app gives you this.
Multi-currency support. Track accounts and assets in any currency — useful for cross-border situations like UK expats, dual-residents, freelancers paid in USD, or anyone holding non-GBP investments. FX conversion is built in, with prices updated automatically.
UK-first design. ISA & pension headroom, UK tax bands (including Scottish rates), Plan 1/2/4/5 student loans, UK-specific mortgage modelling, and stamp duty calculations. Most finance apps treat the UK as an afterthought; Vault doesn't.
Property and equity tracking. Model property value, mortgage balance, and net equity together — including linking a tracked mortgage account to a property so it isn't double-counted.
Financial Storyteller. Model real decisions in real numbers — compound investing, mortgage overpayments, rent vs buy, debt payoff, sabbatical costs. Every scenario shows what the maths actually says.
Crypto, investments, pensions in one place. All asset types tracked together with live pricing, with the same privacy guarantees as everything else.
The roadmap is shaped by what real users find missing or unclear. Recent and upcoming work includes deeper retirement planning, more UK tax scenarios, a richer guided tour, and ongoing accuracy improvements to the existing calculators.
The core promise — local-first, privacy-first, free — won't change. New features are added when they help people understand their money better, not when they generate revenue.
Word of mouth is how Vault grows. If it's been useful to you:
Send it to one person who'd benefit. There's a built-in share card on the home page that gives you a one-click copy link.
Subscribe to Reasonable Money and forward the issues you find useful. The newsletter is the main place new ideas get road-tested.
Mention it to a colleague or in a money-focused community. The people most likely to benefit are the ones who care about privacy, hate subscriptions, or live in a UK financial situation that off-the-shelf apps don't handle well.
Send feedback. Bug reports, feature requests, weird edge cases — all welcome via the feedback form above. Every email is read.
Once the page has loaded, most features work offline because the app runs in your browser. Live price updates (crypto, investments, FX rates) require an internet connection, but everything else — net worth tracking, spending, planning, tax — works without one.
Vault works best for people who want a clear picture of their finances without the friction of bank logins, sign-up flows, or subscriptions. UK-based users get the most out of it because of the UK-first tax and account modelling — but it works for non-UK users too.
If you want automated transaction categorisation pulled directly from your bank, Vault isn't that — by design. Vault is a manual-input tool that gives you total control and total privacy in exchange for a few minutes of setup.