Most portfolio apps want an account, an email, often even an exchange login. They pull your prices from the network, store your holdings in the cloud, and end up knowing more about your wealth than you would like. The Sachwert-Tresor ("tangible-asset vault") does the opposite: a single, local vault for your Bitcoin, gold and silver — fully offline, no account, no KYC, no cloud. Your data never leaves your device in plaintext.
Try it right in your browser
No download, no account — the web version runs instantly, everything stays in your browser.
→ Open the Sachwert-TresorWhat it does
- Bitcoin, gold & silver — record buys, sells and withdrawals. Metals by count × denomination (coin/bar, fineness, dealer).
- Net holdings & value — what you actually hold, plus invested cost. You enter current prices yourself (deliberately no network lookup) → value and profit/loss from that.
- EUR, USD or CHF — record each entry in its own currency (since v2.1). Totals stay separate per currency, nothing is converted — the app never fetches exchange rates. Optionally add the EUR equivalent from the transaction date so the tax-tool export stays complete.
- KYC separation — broker buys (KYC) and private/P2P (noKYC) stay cleanly separated.
- Tax-tool export — exports
manual_buys.csv/manual_sales.csvstraight into the format of the BTC tax tool. - Encrypted backup & sync — the
.vaultfile is fully encrypted and can be synced between devices via Syncthing, without any cloud. - Bilingual — German and English, switchable in the app.
Why offline?
A holdings tracker is a map of your wealth. That does not belong on someone else's server. The Sachwert-Tresor makes not a single network request — no price APIs, no trackers, no external scripts. You enter Bitcoin and metal prices manually. That is less convenient than a live ticker, but it is the price for nobody listening in.
Security — and verifiable
- Encryption with AES-256-GCM, key derived from your passphrase via PBKDF2-SHA256 (600,000 iterations) — all through the browser's native WebCrypto, no third-party crypto code.
- Optional 2FA second factor (Aegis / TOTP, RFC 6238) on unlock.
- No reset, no backdoor. Forget the passphrase and the data is gone — but nobody else can get in either.
- Open source. The full client code is public — you don't have to trust, you can check that nothing phones home.
How to get it
In the browser (desktop & phone): just open api.alien-investor.org/tresor/.
As an app (Android / GrapheneOS): deliberately not on the Google Play Store, but via signed releases. Easiest through Obtainium: add the repo URL as a source and it will notify you of every update automatically. Or install the latest APK directly. Or straight from the Zap Store, the app store on Nostr.
Signature fingerprint to verify authenticity (identical across all versions):
SHA-256: 660f210c7a289f388bb4812c23825a77f1fc84e6a7ee58d64281b6bf5cd87988
Why the app protects more than the browser
The web version and the app share the same code — but the native app (since v2.0) is locked down harder at the operating-system level. A website simply cannot do that:
- No INTERNET permission. The app's network right is stripped from the Android manifest entirely — it cannot open a connection at all. "No telemetry" is verifiable, not just promised.
- FLAG_SECURE. No screenshots, no screen recording, no holdings preview in the app switcher.
- No cloud/ADB backup. Your vault data lands in no automatic backup — you make backups yourself, via the encrypted
.vaultfile.
For full protection use the APK. The web version stays the fastest way to try it out.
Open source on Codeberg
The client code is open source (MIT license) and free. Build, signing and server internals stay private; the verifiable part — the app itself — is open. No accounts, no server dependency.
The Sachwert-Tresor is free. If it helps you, the mothership appreciates some fuel — see below. And if you want to file your Bitcoin buys cleanly for tax, the BTC tax tool is the next step: the vault exports straight into its format.