UD5 Toolkit
Polybius Square Cipher Tool – Online Encode & Decode
Encrypt or decrypt text using the classical 5x5 Polybius square. Excludes J or merges I/J.
Atbash Cipher – Reverse Alphabet Encryption
A simple yet powerful cipher that substitutes each letter with its opposite in the alphabet. No keys needed.
Enter Text
Atbash Result
No Encryption Key
Bi-directional mapping means encryption and decryption are identical.
100% Client-Side
Your data never leaves your browser. Total privacy.
Instant Conversion
Real-time transformation as you type. No page reloads.
Frequently Asked Questions
The Atbash cipher is a substitution cipher where each letter of the alphabet is mapped to its reverse counterpart. Originally used with the Hebrew alphabet, it has been adapted to English as A↔Z, B↔Y, C↔X, etc. It’s symmetric, meaning the same process encrypts and decrypts a message.
For each letter in the plaintext, it is replaced with the letter in the same position from the end of the alphabet. For example, 'A' (position 1) becomes 'Z' (position 26), 'B' becomes 'Y', and so on. Non‑alphabetic characters (numbers, spaces, punctuation) remain unchanged.
No, the Atbash cipher offers no real security by modern standards. It’s a classic example of a monoalphabetic substitution cipher that can be broken instantly with basic pattern recognition. Use it only for puzzles, learning, or light obfuscation, never for sensitive data.
The Caesar cipher shifts letters by a fixed number of positions (e.g., +3). Atbash uses a fixed reflection of the alphabet. Caesar requires a key (the shift amount); Atbash has none. Both are easy to break but serve as excellent introductions to cryptography.
Yes. Uppercase letters are transformed to uppercase, and lowercase to lowercase. For example, 'A' becomes 'Z', while 'a' becomes 'z'. Any character that is not an English letter remains exactly as entered.
Absolutely. Since the cipher is its own inverse, simply paste the encoded text into the input area and the output will be the original message. Our Swap button also lets you quickly exchange input and output for convenience.
Base58 Encoder & Decoder - Online Bitcoin-Style Address Tool
Encode or decode data to/from Base58 (Bitcoin alphabet). Useful for cryptocurrency address generation testing. Fully local, no data sent.
URL Component Encoder/Decoder - Online encodeURIComponent
Encode or decode a string for use in a URL query parameter. See the raw and encoded versions. Dev tool.
SSL Cipher Suite Checker - Online Test TLS Security
Check which cipher suites a website supports and identify weak or outdated ones. Quick security audit from your browser.
Geohash Encoder/Decoder - Online Lat/Lon to String
Encode latitude/longitude into a geohash string and decode a geohash back to coordinates with precision info. Local algorithm.
Hashid Encoder/Decoder - Online Short Unique IDs from Numbers
Convert integers into short, unique, YouTube‑style IDs (hashids) and decode them back. Customize salt and minimum length.
File to Base64 Encoder/Decoder - Online Download
Encode any file into a Base64 string that you can copy, or decode a Base64 string back to a downloadable file. Pure frontend.
Text to Emoji Cipher - Online Encode Secret Messages
Convert your text into a string of emojis using a simple substitution cipher. Share secret messages that look fun. Decode them with the same tool. All local.
Email Obfuscator - Online Protect Address from Bots
Hide your email address from scrapers by encoding it using HTML entities and CSS tricks. Still clickable for real users. Local generator.
Emoji Cipher Decoder - Online Secret Message Fun
Decode a message hidden in a string of emojis (each emoji maps to a letter). Fun game for kids. Create your own.
String to Escaped HTML - Online Protect Against XSS
Instantly convert plain text into HTML‑safe escaped characters for secure display in web pages. Prevent cross‑site scripting. All processing local.
Letter Frequency Analyzer - Online ETAOIN SHRDLU
Paste text to see a live letter frequency bar chart. Helps break substitution ciphers. All local analysis.
Pigpen Cipher Encoder - Online Masonic Symbol Translator
Encrypt text into the classic pigpen symbols and decode them back. Fun for treasure hunts and mystery games.
HTML Escape/Unescape - Online Encode Special Characters
Escape HTML special characters to prevent XSS attacks, or unescape HTML entities back to original text. Essential for web developers. Runs locally.
String Obfuscator - Online Text Encoder to Hide Content
Obfuscate strings using simple techniques to prevent casual reading. Useful for hiding spoilers or email addresses from bots. Decode with the same tool.
Image to Base64 Converter - Online Encode Picture to Text
Transform any image into a Base64 data URI for embedding directly into HTML, CSS, or JSON. Drag and drop support. Entirely browser-side conversion.
ROT13 Encoder & Decoder - Online Caesar Cipher ROT13
Easily apply ROT13 cipher to obfuscate or reveal text. A classic letter substitution cipher that works bidirectionally. Purely client-side processing.