rentczecher is open source. All the code is on GitHub, a star is always appreciated →
rentczecher
GitHub
CSEN

Installing on Windows and macOS

rentczecher isn't code-signed yet, so Windows and macOS warn you the first time you open it. Here is how to get past the warning. You only do it once.

Windows

Download

  1. Download the installer. If Microsoft Edge holds it as not commonly downloaded, open the download’s ⋯ menu, choose Keep, then Show more and Keep anyway.

  2. Open the installer. Windows shows a blue screen, Windows protected your PC. Click More info.

  3. Check that the app is rentczecher-windows-x64-setup.exe and click Run anyway.

  4. Go through the installer as usual. The app then opens without a warning, every time.

No Run anyway button?

Then Smart App Control is on, which blocks every app that is not signed, with no exception for one app. You can turn it off in Windows Security → App & browser control → Smart App Control settings. On an older Windows 11 that has not installed the 2026 updates, it cannot be turned back on without reinstalling Windows, so only do that if you are sure.

macOS

Download

  1. Download the installer, open it and drag rentczecher into Applications.

  2. Open rentczecher from Applications. macOS says it could not verify the app is free of malware. Click Done.

  3. Open System Settings → Privacy & Security and scroll down to Security. Next to “rentczecher” was blocked, click Open Anyway. The button stays there for about an hour after you tried to open the app.

  4. Enter your password or use Touch ID, then click Open Anyway once more. From now on the app opens normally.

On macOS 14 Sonoma and older it is quicker. Control-click the app in Applications, choose Open, then Open again.

macOS says the app is damaged?

The app is fine. macOS sometimes says that about apps from outside the App Store and then offers no Open Anyway. Open Terminal, paste this line and press Enter. It removes the mark macOS gave the downloaded app, and the app then opens.

xattr -dr com.apple.quarantine /Applications/rentczecher.app

Why the warning?

Windows and macOS trust an app when it is signed with a certificate that names its developer. rentczecher is not signed yet, so both systems say they do not know who made it. They say nothing about whether the app is safe.

A signed Windows installer is on the way. On macOS, signing needs Apple’s developer program, which costs €99 a year, and I earn nothing from the app. So on a Mac the warning stays for now.

Every line of the app is public on GitHub, and every installer is built there from that code.