(SECUSO) On the fly measurements with your Smartphone as ruler or protractor.
About this app
Privacy Friendly Ruler can display a ruler or protractor at the edge of the display. This enables on the fly measurements with the smartphone. It belongs to the Privacy Friendly Apps group developed by the research group SECUSO at Karlsruhe Institute of Technology. More information can be found an secuso.org/pfa/
What makes Privacy Friendly Ruler different from other similar apps?
1. No permissions Privacy Friendly Ruler does not require any permissions.
2. No advertisement Many other free apps in the Google Play Store dazzle annoying advertising and also shortens battery life.
Feel free to contact us via: Bluesky - @secusoresearch.bsky.social https://bsky.app/profile/secusoresearch.bsky.social Mastodon - @SECUSO_Research@bawü.social https://xn--baw-joa.social/@SECUSO_Research/ Job opening - https://secuso.aifb.kit.edu/english/Job_Offers.php
Licensed under GPL-3.0-only, by SECUSO - Security Usability Society.
What's New in v1.1.4
Imported from the F-Droid repository index.
Version history
Jul 21, 2025 · 6.1 MB · Android API 17–34 · code 100
Imported from the F-Droid repository index.
SHA-256 aa4f1096a4131fd7673f9fea8897598c34b935703a78b1b753c3a104579ea351
Apr 25, 2025 · 4.5 MB · Android API 17–34 · code 6
Imported from the F-Droid repository index.
SHA-256 332753390d74359e142cc928f4f29e126a876a6be7f9d28fcab0b6d770b93d1a
Jan 6, 2025 · 2.8 MB · Android API 17–34 · code 5
Imported from the F-Droid repository index.
SHA-256 6138235ff15a8ee17a4e7a704b32b71530823a240e5ffda4fe8d809294916719
Will it run on your device?
73%
- Runs on a broad range of modern Android versions.
- ABI coverage is focused on newer 64-bit devices.
Installation Guide
Open Settings on your Android device
Go to Security → Unknown sources (or Install unknown apps)
Enable "Allow from this source" for your browser or file manager
Open the downloaded APK file from your Downloads folder
Tap "Install" and wait for installation to complete
Launch the app from your home screen
Make sure to re-enable Unknown Sources restrictions after installation for security.
How to install this safely
How to verify the file you downloaded
Before you install anything, confirm the file is the one described here. On a computer, run shasum -a 256 your-download.apk (macOS or Linux) or certutil -hashfile your-download.apk SHA256 (Windows), then compare the output character-for-character with the SHA-256 on this page. If a single character differs, the file is not the build we recorded — delete it.
What the signing certificate proves
Every Android app is signed with a private key that only its developer holds. The fingerprint on this page is a hash of the matching public certificate, and it proves continuity rather than identity: it tells you a build came from whoever signed the earlier ones. Android enforces this at install time — if a package claiming to be org.secuso.privacyfriendlyruler is signed with a different key, the system will refuse to install it over your existing copy. A fingerprint that changes between releases is worth pausing on, because a repackaged app that has been modified by someone else cannot keep the original signature.
How to roll back to an earlier version
If the current release misbehaves, 1.1.3 is the last build before it. Android will not install an older version code over a newer one, so you must uninstall Ruler (Privacy Friendly) first — which clears its local data unless you have a backup. Reinstall the older APK only if its signing fingerprint matches the build you already trust, and check the API range: an older release may target an Android version your device has moved past.
Why we list sources instead of hosting everything
The official store channel is almost always the right choice: it updates automatically and carries the publisher's own distribution guarantees. A direct APK is useful when a device has no store access, when a rollout has not reached your region, or when you need a specific version — and only when the publisher has authorized that copy. APKBrowse does not list pirated, cracked, or unauthorized rebuilds of Ruler (Privacy Friendly), and a listing is removed when the evidence for it stops holding up.
Get Ruler (Privacy Friendly)
Every source we list for org.secuso.privacyfriendlyruler is legality-reviewed. Pirated or cracked builds are never offered.
Other sources
F-Droid listing
officialF-Droid builds this app from source and signs it. This is its official listing, with older builds and full release notes.
Source code
verified publisherThe upstream repository this build is compiled from.
We check legality and signature continuity, but device behaviour still varies. Install at your own discretion.
App Information
Security Verification
We record provenance; we do not run malware scans. Verify the hash yourself before installing.
SHA-256 Hash
aa4f1096a4131fd7673f9fea8897598c34b935703a78b1b753c3a104579ea351
Signing certificate
3affcdf2af47e2473a3a9ec50bac8e2bb45d26d903e70ad7dc7e360b942a3842
Permissions Required
What each permission lets Ruler (Privacy Friendly) do. A highlighted one is worth a second look — not necessarily wrong, just worth asking whether this app needs it.
Previous Versions
The signing certificate fingerprint for this release is on record, so a build that does not match it did not come from this publisher.
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