Caesar Cipher Decoder

Right-click any selected text to instantly see all 25 Caesar cipher shifts. Fast, offline, no data leaves your browser.

Caesar Cipher Decoder gives you instant, offline brute-force decoding of Caesar-shifted text, right from your browser's context menu. HOW IT WORKS • Select any ciphertext on any web page. • Right-click → "Decode as Caesar Cipher". • A new tab opens showing all 26 shift candidates (0 = original, 1-25 = decoded). • Click any row to copy the plaintext. PRIVACY • 100% offline. No network calls, no telemetry, no tracking, no data collection. • Only one Chrome permission: contextMenus. The extension cannot read page contents, only the text you explicitly select and pass via the right-click menu. • Open source — see the GitHub repository linked below. DESIGNED FOR • CTF players solving classical-cipher challenges • Cryptography students • Puzzle enthusiasts • Security researchers eyeballing encoded strings NEED MORE CIPHER TOOLS? This extension is deliberately single-purpose. For Vigenère, Atbash, Autokey, Rail Fence, Playfair, and 20+ other classical ciphers, plus encoding and step-by-step walkthroughs, visit the companion site at caesarcipher.org.