Caesar Cipher
Choose a cipher, type your text, and instantly encrypt or decrypt it. Supports Caesar shift, ROT13, ROT18 (digits too), Atbash reversal, and Vigenère keyword cipher.
About the ciphers
The Caesar cipher is one of the oldest encryption techniques, named after Julius Caesar who reportedly used a shift of 3 to protect his military messages. Each letter is shifted a fixed number of positions in the alphabet; non-alphabetic characters are left unchanged, and case is preserved.
ROT13 is a special case of the Caesar cipher with a shift of 13. Because the English alphabet has 26 letters, applying ROT13 twice returns the original text — the same function encrypts and decrypts. It is widely used in online forums to hide spoilers and puzzle answers.
ROT18 extends ROT13 by also rotating digits: digits are shifted by 5 (ROT5), so 0 ↔ 5, 1 ↔ 6, and so on. Like ROT13, it is self-inverse.
Atbash replaces each letter with its mirror: A↔Z, B↔Y, C↔X, etc. It was used in the Hebrew alphabet and appears in the Book of Jeremiah. Applying Atbash twice restores the original text.
The Vigenère cipher is a polyalphabetic substitution cipher — different letters in the plaintext are shifted by different amounts, determined by a repeating keyword. This makes frequency analysis much harder than for simple shift ciphers. Enter your keyword in the field provided; only letters are used as key characters.
Using the character frequency chart
The bar chart below the output shows how often each letter appears in the ciphertext. In English plaintext, E, T, A, O, I, N are the most common letters. If the cipher is a simple substitution, you can often identify the shift by finding the cipher character that appears most frequently and assuming it maps to E. The Vigenère cipher disrupts this pattern by cycling through multiple shifts.
Related Tools
Binary to Text Converter
Convert text to binary, hex, and Base64 — or decode binary, hex, and Base64 back to plain text.
Text Case Converter — UPPER, lower, Title, camelCase
Convert text to sentence case, lower case, UPPER CASE, Title Case, camelCase, snake_case, and more.
Duplicate Word Finder Online
Find and highlight duplicate words in your text. Sort by frequency and copy with highlights.
Word & Sentence Counter Online
Count sentences, words, characters, paragraphs, and estimate reading time instantly.
Free Online Notepad — Auto-Save
A simple notepad that auto-saves to your browser. No account needed, works offline.
Free APA Citation Generator — 7th Edition
Generate properly formatted APA 7th edition citations for journals, books, and websites. Free, no account needed.
Phonetic Spelling Tool Online
Convert English text to a phonetic spelling guide to help with pronunciation.
Roman Numeral Converter Online — Numbers & Dates
Convert numbers and dates to Roman numerals, or decode Roman numerals back to numbers.
Word Cloud Generator Online
Generate a visual word cloud from your text. More frequent words appear larger.
Em Dash Remover — Remove — from Text Free Online
Instantly remove or replace em dashes (—) and en dashes from your text. Paste, clean, copy — free.
Remove Line Breaks Online
Remove unwanted line breaks and clean up paragraphs in your text.
Character Remover — Delete Any Character from Text Free
Remove or delete any character, symbol, or string from your text instantly. Case-sensitive, free, no install.
Remove Underscores from Text
Replace underscores with spaces, hyphens, or remove them entirely.
Reverse Text Generator Online
Reverse text character-by-character, word-by-word, or line-by-line.
Remove Extra Whitespace Online
Trim, collapse, or strip all whitespace from your text.
Repeat Text Generator Online
Repeat any text a specified number of times with a custom separator.
Remove HTML Tags Online — Strip HTML & Markdown
Remove HTML tags and strip Markdown formatting to get clean plain text instantly.
Remove Duplicate Lines Online
Remove duplicate lines from text, keeping only unique lines.
Sort Words Alphabetically Online
Sort words or lines alphabetically, ascending or descending.
Find & Replace Text Tool Online
Find and replace text with support for regex and case-sensitive matching.
Word Frequency Counter Online
Count how many times each word appears in your text, sorted by frequency.
NATO Alphabet Translator Online
Translate text into the NATO phonetic alphabet — Alpha, Bravo, Charlie…
Pig Latin Translator Online
Translate English text into Pig Latin for fun.
Plain Text Converter — Strip HTML & Markdown
Strip HTML, Markdown, and special formatting to get clean plain text.
Readability Score Calculator
Analyse text readability with Flesch, Gunning Fog, Flesch-Kincaid, and Coleman-Liau scores.
Text Summarizer
Extractive text summarization without AI — scores sentences by TF-IDF frequency and position. Adjust summary to 1–10 sentences.
Number to Words Converter
Convert any integer up to 999 quadrillion to English words — cardinal, ordinal, and currency forms.
Markdown Table Generator
Build Markdown tables visually. Edit headers and cells, add rows and columns, set alignment, and copy Markdown or HTML.
Emoji Picker
Browse and search over 200 emojis across 8 categories. Click to copy. Supports skin tones and tracks recently used.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text by word count, sentences, or paragraphs.
Markdown Live Preview
Write Markdown and see the rendered HTML preview in real time. Includes a toolbar with formatting shortcuts and word count.
Morse Code Translator
Translate text to Morse code or decode Morse code back to text. Covers the full International Morse Code character set.
URL Slug Generator
Convert any text to a URL-friendly slug. Handles accented characters and formats text for clean SEO-friendly URLs.
Text to Binary Converter
Convert text to binary (0s and 1s) or decode binary back to text. Uses UTF-8 encoding for correct Unicode support.
Typing Speed Test — Free WPM Test Online
Test your typing speed and accuracy for free. Real-time WPM counter, character-level feedback, and accuracy score.
Word Counter Online — Count Words, Characters & More Free
Count words, characters, sentences, paragraphs and estimate reading time instantly. Free online word counter — no sign-up needed.
Roman Numeral Converter — Number to Roman & Roman to Number
Convert numbers to Roman numerals and back. Supports 1–3999. Free online Roman numeral converter with conversion table.