The ultimate interactive calculator and handbook for SysAdmins, DevOps, and Students. Visualize permissions, generate commands, and learn the logic behind the terminal.
CHMOD Lab is the missing manual for file permissions. Whether you are setting up a web server or learning Linux for the first time, this tool helps you calculate Octal codes, understand Symbolic notation, and generate the perfect command instantly.
Toggle Read, Write, and Execute bits visually. Watch the Octal (755) and Symbolic (rwxr-xr-x) values update in real-time. No more mental math errors.
Octal & Symbolic Support Whether you prefer the precision of numbers (777) or the clarity of letters (u+x), CHMOD Lab handles both. Switch modes instantly to see how they translate to one another.
Education First The "Special Modes" section helps you understand advanced security concepts like SetUID (4), SetGID (2), and the Sticky Bit (1)—critical knowledge for any serious Linux administrator.
From instant calculations to air-gapped security. Everything you need to master chmod without the risk.
Stop doing mental math. Toggle the Read, Write, and Execute checkboxes instantly and watch the Octal (755) and Symbolic (rwxr-xr-x) values update in real-time.
Forget Googling "chmod cheat sheet." The app includes a complete offline reference guide with calculation logic, common flags, and a library of the top 20 most used commands.
Don't just calculate numbers—generate commands. With one tap, copy the full syntax (e.g., chmod -R 777 ./var/www) directly to your clipboard, ready for the terminal.
Your workspace, your style. Switch between 6 professional skins, including the high-contrast Magma, the retro-green Terminal, and the sleek Cyberspace.
Go beyond the basics. We fully support special permission bits including SetUID (4), SetGID (2), and the Sticky Bit (1), giving you total control over the 4-digit format.
Built for security-conscious environments. CHMOD Lab runs 100% offline with native Swift code, ensuring your server configurations never leave your device.
The app includes a complete offline reference guide with calculation logic, common flags, save settings and a library of the top 20 most used commands.
Demystify Linux permissions by understanding exactly who you are granting access to.
Quick lookups for common values.
Tap on a saved to view full card
Designed for Your Environment CHMOD Lab looks great in the server room or under the sun. Choose from 6 stunning, professionally designed themes to match your setup.
Dark Mode Collection
Light Mode Collection
Streamline your workflow with saved permission profiles.
Eliminate repetitive syntax entry. Our Quick Load library lets you store and label complex chmod configurations. Build a library of standard environment profiles (e.g., Production, Staging, Local) and deploy them to files or directories instantly. It’s the fastest way to ensure consistency across your file system without memorizing octal codes.
Some questions about CHMOD Lab answered the most below
Both! You can copy just the permission code (e.g., "755") or the full command syntax including flags (e.g., chmod -R 755 filename).
This allows you to bookmark specific permission sets. If you manage multiple environments, you can save a "Production Web Server" card (755) and a "Private SSH Key" card (600) and switch between them instantly without recalculating.
Absolutely. CHMOD Lab is a native utility. It requires no internet connection, no login, and sends no data to the cloud. It is completely air-gapped safe.
The Handbook is your offline textbook. It covers everything from the basic "4-2-1" calculation logic to a reference table of the "Top 20 Popular Commands" used by professionals worldwide.
Go to Settings to toggle between our 6 custom skins. Whether you prefer the intense heat of Magma, the retro cool of Terminal, or the clean look of Aether, there is a style for you.
100% Offline. No servers, no tracking, no accounts. The app works perfectly without an internet connection.
