The Playfair cipher is a digraph substitution cipher invented by Charles Wheatstone in 1854 and promoted by Lord Playfair. It encrypts pairs of letters (digraphs) rather than single letters, making it more secure than simple substitution ciphers. The encryption uses a 5×5 matrix built from a keyword, with the letters A-Z (excluding J). Each pair of letters is encrypted using three rules: if in same row, shift right; if in same column, shift down; otherwise, form a rectangle and swap corners. This calculator provides both encryption and decryption, handling text preparation automatically (removing spaces, replacing J with I, inserting X between double letters). The Playfair cipher is an excellent introduction to classical cryptography and is still used in some educational contexts.
Text Tools
Find and Replace Text – Bulk Search & Replace Tool
A text replacement tool finds all occurrences of a specific word, phrase, or character sequence in a given text and replaces them with another. This operation is fundamental in text editing, content management, and data cleaning. The replacement can be case-sensitive (distinguishing between uppercase and lowercase letters) or case-insensitive. It can also be limited to whole words only, which prevents replacing parts of larger words (for example, replacing "cat" in "category" when "whole words only" is enabled). The tool uses a search algorithm that scans the entire text and performs substitutions in one pass. It is particularly useful for standardizing terminology, correcting common typos, updating product names, or preparing texts for publication. All replacements are shown instantly in the result area, and you can always reset to the default example.
Change text case – free online letter case converter tool
The "Change Text Case" tool is a versatile converter that transforms your text into different letter case formats with a single click. Whether you need to standardize headings, format code variables, or prepare content for publication, this tool handles it all.
In theory, case conversion works by applying Unicode character mapping rules. Each letter in your text has a corresponding uppercase or lowercase representation based on the Unicode standard. The tool uses JavaScript string methods like toUpperCase() and toLowerCase() for basic conversions. For more complex formats like Title Case (capitalizing each word) or Sentence case (capitalizing only the first letter of each sentence), the tool uses pattern matching to identify word boundaries and punctuation marks, then applies capitalization rules accordingly.
Additional formats like camelCase (removing spaces and capitalizing internal words) and snake_case (replacing spaces with underscores) follow specific programming conventions. This makes the tool invaluable for developers, writers, and content creators who need quick text formatting.
Text File Encoding Detector – Identify Character Encoding of Your Files
What is Text File Encoding Detector?
This tool analyzes text files or pasted text to identify the character encoding used. Character encoding defines how bytes are mapped to characters (letters, numbers, symbols). Common encodings include UTF-8, UTF-16, ASCII, Windows-1251 (Cyrillic), and ISO-8859-1 (Latin).
How it works in theory: The detector examines the byte sequence of your input. It looks for Byte Order Marks (BOM) that indicate UTF-8, UTF-16, or UTF-32. It checks for null bytes (common in UTF-16/32). It validates UTF-8 byte sequences according to the UTF-8 specification. If all bytes are in the 0-127 range, it's ASCII. If bytes are in the 128-255 range and don't form valid UTF-8, the encoding is likely a single-byte code page like Windows-1251 or ISO-8859-1. The tool provides a hex preview for technical verification.
This helps developers, translators, and data analysts identify encoding issues that cause garbled text (mojibake).
JSON to HTML Table Calculator
What is JSON to HTML Table Calculator?
This tool converts a JSON array of objects into a visual HTML table and automatically calculates key statistics for every numeric column: count, sum, average, minimum, and maximum. It is designed for developers, data analysts, and anyone who works with structured data.
How it works in theory: The tool parses your JSON input, validates its structure, and extracts all object keys as table headers. Each object becomes a row. For numeric fields, it computes descriptive statistics using basic arithmetic: sum (total of all values), average (sum divided by count), min (lowest value), and max (highest value). The result is presented as a clean HTML table with a statistics summary below.
This is not just a converter – it's a lightweight data analysis tool that gives you instant insights into your JSON data without writing code.
Remove All Whitespace from Text – Free Online Tool
This tool removes every space, tab, newline, and other whitespace characters from your text. It scans your input and deletes all Unicode whitespace (including regular spaces, line breaks, and tabs). The result is a continuous string without gaps.
In theory, this process replaces each whitespace character with an empty string. Whitespace characters include space (U+0020), tab (U+0009), newline (U+000A), carriage return (U+000D), and other Unicode space separators. The tool uses a regular expression to match all these characters globally and remove them.
Useful for cleaning data, preparing strings for URLs, compacting code, or when spaces interfere with processing.
Calculator Hill Cipher: Encrypt & Decrypt Online
The Hill cipher is a polygraphic substitution cipher based on linear algebra. Invented by Lester S. Hill in 1929, it encrypts blocks of letters simultaneously using matrix multiplication.
Perfect for learning cryptography, testing matrices, or quickly encoding messages. All processing runs in your browser — no data is sent to any server.