文字ケースの簡単なガイド
文字ケースとは、書き言葉が大きな大文字と小さな小文字をどのように区別するかを指します。両方を持つ表記体系では、各大文字に対応する小文字が存在し、名前・発音・アルファベット順の位置を共有しています。以下は本ツールが行う変換と、それぞれの使いどころを簡潔に紹介するものです。
UPPERCASE
Every letter rendered in its capital form. Good for short labels, alerts and acronyms; avoid for anything longer than a few words — it's slower to read and can come across as shouting.
THIS IS AN EXAMPLE OF UPPERCASE IN USE.
lowercase
Every letter rendered in its small form. Lowercase is the default for body copy in most modern writing — easy to scan, quiet on the page.
this is an example of lowercase in use.
Sentence case
Only the first letter of each sentence is capitalized — plus proper nouns and anything English grammar normally demands. It's the natural fit for paragraphs, UI copy, and conversational writing.
This is an example of sentence case in use.
Title Case
Capitalizes the major words — nouns, verbs, adjectives — and leaves short articles, prepositions, and conjunctions lowercase. It's the classic headline style for publications and blog posts.
This Is an Example of Title Case in Use.
Capitalized Case
Every word's first letter is capitalized and every other letter drops to lowercase — unlike Title Case, it doesn't spare small words. Common for names, brand marks, and short labels that need a uniform look.
This Is An Example Of Capitalized Case In Use.
aLtErNaTiNg cAsE
Starts lowercase and alternates every subsequent character, regardless of the original casing. Mostly used for stylistic emphasis on social media.
tHiS Is aN ExAmPlE Of aLtErNaTiNg cAsE In uSe.
iNVERSE cASE
Flips every letter to its opposite: capitals become lowercase and lowercase become capitals. Handy for quick visual effects or for auditing unusual capitalization in a source string.
tHIS IS AN EXAMPLE OF INVERSE CASE IN USE.
camelCase
The first word is lowercase and every subsequent word is capitalized, joined without spaces. The default identifier style for JavaScript, Java, and Swift variables and functions.
thisIsAnExampleOfCamelCase
PascalCase
Every word — including the first — is capitalized and joined without spaces. Used for type names: classes, interfaces, and React components.
ThisIsAnExampleOfPascalCase
snake_case
Lowercase words joined with underscores. The standard for Python, Rust, and Ruby identifiers, and for most SQL column names.
this_is_an_example_of_snake_case
kebab-case
Lowercase words joined with hyphens. The convention for URL slugs, CSS class names, and HTML attributes.
this-is-an-example-of-kebab-case
CONSTANT_CASE
Uppercase words joined with underscores. Used for true constants in most programming languages and for environment variables.
THIS_IS_AN_EXAMPLE_OF_CONSTANT_CASE
Reverse
Reverses the order of every character in the text. Useful for quick obfuscation, palindromic checks, or playful typography.
.esu ni esrever fo elpmaxe na si sihT
Clean whitespace
Collapses runs of spaces to a single space, strips leading and trailing whitespace from each line, and removes empty lines. Ideal for sanitizing text pasted from Word or a PDF.
Clean, tidy text on one line.
Dedupe lines
Removes duplicate lines, keeping the first occurrence of each. The order of remaining lines is preserved.
alpha beta gamma
Sort lines
Sorts every line alphabetically using locale-aware comparison. Handy for cleaning up lists, CSV columns, or JSON key sets.
alpha beta gamma
Slugify
Normalizes a string for use as a URL slug: removes accents, strips punctuation and special characters, lowercases everything, and joins remaining words with hyphens. Match what Google expects in URLs and you'll rank better.
this-is-an-example-of-a-slug
Base64 encode
Encodes any UTF-8 text into a Base64 string. Useful for storing binary-safe data in JSON, embedding small assets in HTML, or sharing short payloads in URLs.
VGhpcyBpcyBhbiBleGFtcGxlIG9mIEJhc2U2NC4=
Base64 decode
Decodes a Base64 string back to UTF-8 text. Returns an empty string if the input is not valid Base64.
This is an example of Base64.
URL encode
Percent-encodes a string so it can be safely included in a URL query string or path segment. Spaces become %20, ampersands become %26, and so on.
Hello%20World%20%26%20friends
URL decode
Decodes a percent-encoded URL string back to its original characters.
Hello World & friends
HTML escape
Replaces the five reserved HTML characters (<, >, &, ", ') with their entity equivalents so untrusted text can be safely embedded in HTML.
<script>alert(1)</script>
HTML unescape
Decodes HTML entities (named and numeric) back to their original characters.
<script>alert(1)</script>
Strip Markdown
Removes Markdown syntax — headings, emphasis, code fences, links, images, lists — and returns plain text. Useful when you need a readable preview without rendering full Markdown.
Bold text and a link become plain words.
ROT13
A simple letter substitution cipher that replaces each letter with the one 13 positions later in the alphabet. ROT13 is its own inverse, so applying it twice gives back the original text.
Guvf vf na rknzcyr bs EBG13 va hfr.
Text to binary
Encodes each UTF-8 byte of the input as an 8-bit binary number, separated by spaces. Useful for low-level demos and computer-science exercises.
01001000 01101001
Binary to text
Decodes a sequence of 8-bit binary numbers back into UTF-8 text. Whitespace, commas, and other non-binary characters are ignored.
Hi
Text to hex
Encodes each UTF-8 byte of the input as a two-digit hexadecimal value. Common for debugging encodings and sharing binary data in plain text.
48 65 6c 6c 6f
Hex to text
Decodes a sequence of hexadecimal byte values back into UTF-8 text. Whitespace and non-hex characters are ignored.
Hello
Strikethrough text
Adds a Unicode combining stroke (U+0336) after every character so the text appears crossed out — works in plain text, social bios, and most chat apps.
T̶h̶i̶s̶ ̶i̶s̶ ̶s̶t̶r̶i̶k̶e̶t̶h̶r̶o̶u̶g̶h̶.
Underlined text
Adds a Unicode combining low line (U+0332) after every character so the text appears underlined without HTML or markdown.
T̲h̲i̲s̲ ̲i̲s̲ ̲u̲n̲d̲e̲r̲l̲i̲n̲e̲d̲.
Upside-down text
Maps each character to a visually inverted Unicode counterpart and reverses the order so the result reads like the original flipped 180°.
˙uʍop ǝpᴉsdn sᴉ sᴉɥ┴
Mirror text
Mirrors each character horizontally using reversed Unicode glyphs and reverses string order — like reading text in a mirror.
.bɘɿoɿɿim ƨi ƨiʜT