QuantumFin Wallet — Privacy Policy
Effective 13 November 2026 · Applies to the QuantumFin Wallet app for Android (package io.quantumfin.wallet) and the QuantumFin PQ Wallet browser extension for Chrome. Except where a section names one of them, everything here applies to both.
Summary
- QuantumFin Wallet is self-custodial. Your key is created on your device, encrypted with a passphrase only you know, and never sent to us or anyone else.
- We do not use analytics, advertising, crash reporting or tracking SDKs, and we do not sell or share personal data.
- To show your balance and send transactions, the app talks to the QuantumFin network node. That node necessarily sees your public account identifiers and the transactions you sign, which are public on the blockchain.
Data that stays on your device
| Data | Where and how |
|---|---|
| Your signing key | An ML-DSA-65 key generated on the device and stored only as an encrypted file (Argon2id key derivation, AES-256-GCM) in Android Keystore-backed storage. It is excluded from cloud backup and device transfer. We cannot read or recover it. |
| Your passphrase | Never stored. It is used in memory to unlock the key and discarded. |
| Your recent sends | Recipient, amount and transaction ID of transactions sent from the app, kept in the same encrypted storage so the Activity screen can show them. |
| Backup file | Created only when you choose "Save backup file", written where you choose. It is encrypted with your passphrase. |
Data sent to the QuantumFin network
The app connects over HTTPS to the QuantumFin node at rpc-testnet.quantumfin.io, operated by QuantumFin. It sends:
- your public account identifier and address, to read your balance, account state and history;
- transactions you review and sign (recipient, amount, fee limit, signature), to submit them to the network;
- unsigned transaction drafts, to simulate them before you sign.
Transactions you submit are recorded permanently on the public QuantumFin blockchain and can be seen by anyone. They cannot be deleted by us or by you.
Like any web server, the node's front end receives your IP address with each request. It is used only to deliver the response and to apply per-address rate limits against abuse, and is kept in short-lived server logs. We do not link it to your account.
Camera
The camera is used only when you choose to scan a QR code: a recipient address, or a sign-in code shown by the QuantumFin Explorer. Images are processed on the device and are never stored or transmitted.
Browser extension
The extension works the same way as the app, with these differences:
- Where your data is kept: your encrypted key, wallet settings, activity, connected sites and private-payment notes are stored in the extension's own browser storage on your computer. The key is encrypted with your passphrase, and the extension locks itself after a period of inactivity you choose.
- Network: the extension talks to the QuantumFin node at rpc-testnet.quantumfin.io and, only if that cannot be reached, to the backup endpoint finswap.io/rpc. Both are operated for the QuantumFin Testnet and receive the same data as described above.
- Websites: the extension adds a wallet interface to web pages so that sites can ask to connect. A site learns your address only after you approve the connection. Every transaction or message a site asks you to sign is shown to you for approval first. The extension does not read the content of web pages or your browsing history. The list of sites you connected stays on your computer, and you can remove any of them in Settings.
- Private payments: notes for private payments are created and kept on your computer, and you can back them up. A delivery receipt you send to a payee is shared only with whoever you give it to.
- Fund wallet: the "Fund wallet" button opens the QuantumFin fund page in a new browser tab with your QuantumFin address filled in. That page, and the other wallet you pay from, are outside the extension.
- Permissions: the extension asks for access to https sites only so that it can offer its wallet interface on pages you visit and reach the QuantumFin network. It has no other Chrome permissions.
To delete the extension's data, remove the wallet in the extension's Settings or uninstall the extension.
Signing messages and signing in
A site can ask you to sign a text message, for example to sign in to the QuantumFin Explorer with your wallet. Nothing is signed unless you approve it. The wallet shows you the site and the exact text first. A signed message is not a transaction: it moves no funds and costs nothing.
- What the site receives: when you approve, the site that asked receives your address, your public account identifier, your public key and the signature. The wallet sends nothing else.
- Signing in to the QuantumFin Explorer: the explorer checks the signature and then keeps you signed in with a session cookie. The cookie is only for this sign-in and is not used for tracking. It expires after at most 2 hours without activity, and after 12 hours at most. Signing out ends the session and removes the cookie. To check that the key is current, the explorer also looks up your public account state on the network.
- From your phone: in the app, you can scan the code your browser shows, or type it, to sign in to the explorer in that browser. The app sends the code, your address and the signed message to explorer.quantumfin.io only. The session cookie goes to your browser, not to the app.
What the QuantumFin Explorer keeps
- Sign-in challenges and phone sign-in codes: the explorer stores each challenge it issues (with your address and the challenge text), so that none can be used twice. For a phone sign-in it also stores the code and the IP address of the browser that asked for it. These records are deleted about an hour after they expire; a challenge or code is valid for at most 5 minutes.
- Sessions: while you are signed in, the explorer keeps a session record with your address, your public account identifier, a hash of your public key and the IP address from the latest sign-in or renewal. It is deleted when you sign out or the session expires.
- Sign-in log: to detect abuse, the explorer keeps a log of sign-ins, failed sign-in attempts and phone sign-in approvals, with the time, your address, your public account identifier and the IP address. The IP address is deleted from these entries after 30 days; the time, address and account identifier remain. To have the entries for your address deleted sooner, write to hello@quantumfin.io.
- What you add while signed in: private name tags and your watchlist are stored with your address and shown only to you, until you remove them. Token information you submit for review is stored with your address and, once approved, is shown publicly.
- The explorer does not keep web server access logs. Rate limits against abuse are kept in memory only.
What we do not do
- No account with us, no email or phone number, no identity verification.
- No advertising IDs, contacts, location, photos or files other than a backup file you explicitly open or save.
- No custody: we cannot move, freeze or recover your funds.
Deleting your data
"Settings → Remove wallet from this device" deletes the encrypted key and the local send history from the device; uninstalling the app does the same. Without your backup file and passphrase the wallet cannot be restored by anyone. Blockchain records cannot be deleted. Apart from the QuantumFin Explorer records described above, we hold no other personal data about you.
Children
The app is not directed to children under 18.
Testnet
The current version connects to the QuantumFin Testnet. Testnet QFIN has no monetary value.
Changes and contact
We will post changes on this page with a new effective date. Questions: hello@quantumfin.io.