Caesar Cipher
Shift letters by any amount — encrypt and decrypt with a slider. Includes brute-force mode that shows all 25 possible decryptions at once.
The Spy's Knife for Developers
Ciphers, codes, and covert tools — all offline
Build software without cloud dependencies. The Spy's Knife gives developers 11 specialised tools in a single HTML file that runs entirely offline.
The Spy's Knife is a cryptographic playground in a single HTML file. Encrypt and decrypt with over ten classical ciphers, hide messages in images with steganography, generate number station broadcasts, create QR codes and barcodes, and simulate invisible ink with UV-effect CSS — all running locally with zero network calls.
WHAT'S INSIDE
11 tools in a single HTML file
Vigenère Cipher
Encrypt with a keyword-based polyalphabetic cipher. Shows the Vigenère table and highlights the path through it for each character.
Atbash Cipher
A simple substitution cipher that reverses the alphabet — A↔Z, B↔Y. One click to encode, one click to decode.
ROT13
The classic rotate-by-13 cipher — applying it twice gives you back the original. Useful for hiding spoilers and puzzle answers.
HOW IT WORKS
Three steps. No setup.
1
Download the file
Purchase The Spy's Knife and download a single HTML file. No installer, no account, no setup.
2
Open in any browser
Double-click to open in Chrome, Firefox, Safari, or Edge. Works on any operating system.
3
Start working
Your data stays in your browser's local storage. Nothing is uploaded. Ever.
COMPLIANCE & GEOGRAPHY
Global
Works in any country. No server dependency, no regional restrictions.
FAQ
Frequently Asked Questions
Why should Developers use The Spy's Knife?
The Spy's Knife is built for developers who need puzzles & cryptography tools without cloud dependencies. Ten+ cipher algorithms, steganography, number station generator, QR encoder, barcode generator, and invisible ink simulator. For puzzle makers and escape room designers.
Does The Spy's Knife work offline?
Yes. The Spy's Knife is a single HTML file that runs entirely in your browser. No internet connection required. Your data never leaves your machine.
Is The Spy's Knife a subscription?
No. The Spy's Knife is a one-time purchase ($39). No monthly fees, no renewals, no price increases.
What tools are included in The Spy's Knife?
The Spy's Knife includes 11 tools: Caesar Cipher, Vigenère Cipher, Atbash Cipher, ROT13, Rail Fence Cipher, Morse Code, Steganography, Number Station Generator, QR Code Encoder, Barcode Generator, Invisible Ink Simulator. All accessible from a single HTML file.
Can I try The Spy's Knife before buying?
Yes. Every product page includes an interactive demo you can try in your browser. No signup required.
No cloud One fileOne-time purchase
Get The Spy's Knife — $39Sovereignty as a Service