Case Converter

What this case converter does

This case converter changes the capitalization of any text in one click. Paste a paragraph, a headline, a list of labels or a column of variable names, then choose Sentence case, lower case, UPPER CASE, Capitalized Case, Title Case, aLtErNaTiNg cAsE or iNVERSE cASE. A second row converts words into the developer formats camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and dot.case. The text is converted in place, so you can chain conversions, and Undo and Restore original bring back any earlier version.

Two things separate it from a basic uppercase-to-lowercase converter. Title Case follows a real style guide – AP, APA, Chicago or MLA – so short words such as "of" and "the" stay lowercase where the guide says they should, while the first and last words are always capitalized. And Sentence case is smarter than "lowercase everything, then capitalize after a period": it leaves acronyms and brand names such as NASA and iPhone alone, keeps the pronoun "I" capitalized, and knows that "Dr." or "e.g." does not end a sentence.

Everything runs in your browser. Nothing is uploaded, line breaks and blank lines are preserved, and live counters show characters, words, lines and paragraphs as you work.

How to use the case converter

1. Paste or type your text into the box. The draft is kept in this browser tab, so an accidental refresh does not lose it.
2. Pick a writing case. Click Sentence case, lower case, UPPER CASE, Capitalized Case, Title Case, aLtErNaTiNg cAsE or iNVERSE cASE. The text changes immediately and the button you used stays highlighted.
3. Set the Title Case style if you need one: AP Stylebook (the default), APA, Chicago, MLA or "Capitalize every word". The Keep acronyms and mixed-case words switch decides whether NASA, HTML or iPhone survive Sentence case, Title Case and Capitalized Case.
4. Or pick a code case. camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and dot.case turn each line into one identifier, so twenty column names become twenty identifiers in one click.
5. Copy or download. Copy puts the result on your clipboard and Download .txt saves it as a file. Undo steps back one conversion at a time, Restore original returns the text you started with, and Clear empties the box (Undo brings it back if you clicked by mistake).

Sentence case, title case or capitals?

Sentence case capitalizes the first word of each sentence and proper nouns, nothing else. It is the default for body text and, increasingly, for headings: the BBC and The Guardian write headlines in sentence case, the Google developer documentation style guide and the Microsoft Writing Style Guide require it for headings, and Material Design uses it across app interfaces.

Title case capitalizes the principal words. It remains standard for book, film and song titles, for headlines in US newspapers such as The New York Times, and for headings in APA papers and Chicago-style manuscripts.

UPPER CASE suits acronyms, short warning labels and defined terms in contracts; long passages in capitals are slower to read than mixed case and come across as shouting. lower case is the safe choice for URL slugs, file names and email addresses: the domain part of an address ignores case, but many web servers treat /About and /about as different pages. Capitalized Case is what Word calls "Capitalize Each Word": handy for name lists, but not correct title case because it also capitalizes "of" and "the".

Title case rules by style guide

Style guides agree on the big things – capitalize the first word, nouns, verbs, adjectives, adverbs and pronouns – and disagree on the small ones. In every style the converter also capitalizes the first word after a colon, dash, question mark or period, so subtitles start correctly.

Word type	AP Stylebook	APA 7	Chicago 18	MLA 9
Articles (a, an, the)	lowercase	lowercase	lowercase	lowercase
Coordinating conjunctions	lowercase when under 4 letters (and, but, or, nor, for, yet, so)	lowercase when 3 letters or fewer	lowercase and, but, for, or, nor; capitalize Yet, So	lowercase and, but, for, nor, or, so, yet
Short prepositions (at, by, in, of, on, to, per, via)	lowercase	lowercase	lowercase	lowercase
Four-letter prepositions (with, from, into, upon)	Capitalize	Capitalize	lowercase	lowercase
Longer prepositions (about, through, between)	Capitalize	Capitalize	Capitalize (5+ letters)	lowercase
"as" and "if"	lowercase	lowercase	"as" lowercase, "If" capitalized	"as" lowercase, "If" capitalized
"up" and "off"	Capitalize	lowercase	Capitalize	Capitalize
Short verbs and pronouns (Is, Be, Are, It)	Capitalize	Capitalize	Capitalize	Capitalize
First and last word	Capitalize	Capitalize	Capitalize	Capitalize
Hyphenated compounds	Self-Esteem	Self-Esteem	Self-Esteem	Self-Esteem

AP and APA share the same three-letter threshold. The one difference in this converter is that APA's own list of short prepositions includes "up" and "off", so APA gives "Turn off the Lights" where AP gives "Turn Off the Lights". Chicago's 18th edition (2024) changed its rule: prepositions of five or more letters are now capitalized, where the 17th edition lowercased every preposition. Input: a beginner's guide to working with the API through node.js

• AP or APA: A Beginner's Guide to Working With the API Through Node.js
• Chicago 18: A Beginner's Guide to Working with the API Through Node.js
• MLA: A Beginner's Guide to Working with the API through Node.js
• Capitalize every word: A Beginner's Guide To Working With The API Through Node.js

"API" survives because it is written in capitals, "Node.js" is treated as one word, and "a" is capitalized only because it comes first.

Case conventions in code

Use the code cases to rename a list of fields when moving data between systems – for example turning first_name from a PostgreSQL column into firstName for a JavaScript API response.

Context	Variables and functions	Classes and types	Constants	Notes
JavaScript / TypeScript	camelCase	PascalCase	UPPER_SNAKE_CASE	React components are PascalCase
Python (PEP 8)	snake_case	PascalCase	UPPER_SNAKE_CASE	Modules and files are snake_case
Java / Kotlin	camelCase	PascalCase	UPPER_SNAKE_CASE	Packages are dot.case (com.example.app)
C# (.NET)	camelCase locals, PascalCase methods	PascalCase	PascalCase	Private fields often _camelCase
Go	camelCase unexported, PascalCase exported	same rule	MixedCaps, no underscores	Capitalization controls visibility
Rust and Ruby	snake_case	PascalCase	SCREAMING_SNAKE_CASE	Rust's compiler warns about violations
CSS / Sass	kebab-case classes, --kebab-case custom properties	–	–	BEM uses block__element--modifier
URLs and slugs	lowercase kebab-case	–	–	Google recommends hyphens over underscores
SQL (PostgreSQL)	snake_case tables and columns	–	–	Unquoted identifiers fold to lowercase
Shell and environment variables	UPPER_SNAKE_CASE	–	–	DATABASE_URL, NODE_ENV
Configuration and i18n keys	dot.case	–	–	spring.datasource.url, nav.home.title

The code converter splits text into words at spaces, hyphens, underscores, dots and other punctuation, and at the "humps" of existing camelCase, so getHTTPResponse code becomes get, HTTP, Response and code. Acronyms are then normalized like any other word: getHttpResponseCode, get_http_response_code, GET_HTTP_RESPONSE_CODE. A plural acronym stays one word, so userIDs becomes user_ids and URLs becomes urls, not ur_ls. Apostrophes are dropped (don't stop becomes dontStop), digits stay attached to the preceding word (html5 parser becomes html5Parser), and each line is converted separately, so blank lines and list order are preserved.

How the converter handles tricky text

Sentence endings. A new sentence begins after a period, exclamation mark or question mark – even when a closing quote or bracket follows – at the start of every line, and after a list marker such as "1.", "2)" or "a.". The marker itself keeps its case.

Abbreviations. No new sentence starts after an ellipsis (… or ...), a single initial (J. K. Rowling), an abbreviation with internal periods (e.g., i.e., U.S., a.m., Ph.D.) or a common title such as Dr., Mr., Mrs., Ms., Prof., St., Inc., Ltd. or vs. Decimals such as 3.5 are never sentence ends. "etc." is treated as a sentence end because in most text it is one.

Acronyms and shouting. With the switch on, words in all capitals (NASA, HTML5) and words with an internal capital (iPhone, JavaScript, McDonald's) keep their spelling. A line of two or more words written entirely in capitals, or a whole text in capitals, is treated as shouting and converted anyway. That is what you want when a form has forced an address into capitals. A line holding a single acronym, such as "NASA" on its own, is kept.

Abbreviations in titles. A period after an abbreviation does not start a subtitle, so the result is "Batman vs. the Joker" and "Mr. and Mrs. Smith", not "Vs. The Joker" or "Mr. And Mrs.". A colon, dash, question mark or sentence-ending period does start one: "Dr. Smith Goes to Washington. The Sequel".

Words that only look like prepositions. "Past", "near", "like" and "in" are prepositions in some titles and nouns, adjectives or verbs in others. After "the", "a", "my" or another determiner the converter treats the word as a noun or adjective ("The Past Is Never Dead", "The In Crowd"). After a subject such as "we", "they" or "some", "like" is treated as a verb ("Some Like It Hot"). Elsewhere it stays lowercase where the style asks for it ("Cities like Paris" in Chicago and MLA).

Apostrophes, hyphens and particles. "don't" is one word, so Title Case gives "Don't", not "Don'T". Hyphenated compounds are split, so "state-of-the-art" becomes "State-of-the-Art" and "mother-in-law" becomes "Mother-in-Law". "Up", "down", "off", "out" and "over" are capitalized because in titles they are usually adverbs (Sold Out, Turn Down the Lights). The exception is APA, which lists "up" and "off" as short prepositions and lowercases them. A short word is also capitalized when it is followed by a comma or ends the title (What Are You Waiting For?).

Proper nouns. Sentence case cannot tell "Paris" from "party", so a mid-sentence name in ordinary capitalized form loses its capital. Skim the result for names before publishing.

Changing case in Word, Google Docs and Excel

• Microsoft Word: select the text and press Shift+F3 to cycle between lowercase, UPPERCASE and Capitalize Each Word. Home → Change Case (the Aa button) lists all five options including tOGGLE cASE. On a Mac laptop you may need fn+Shift+F3.
• Google Docs: Format → Text → Capitalization offers lowercase, UPPERCASE and Title Case. There is no sentence case option and no default shortcut, and Title Case capitalizes every word.
• Excel and Google Sheets: use =UPPER(A1), =LOWER(A1) and =PROPER(A1). There is no sentence case function; the usual workaround is =UPPER(LEFT(A1,1))&LOWER(MID(A1,2,LEN(A1))).
• VS Code: the Command Palette has Transform to Uppercase, Lowercase, Title Case, Snake Case, Camel Case and Kebab Case, none with a default shortcut.

Those commands are fine for a single word. The reasons to paste text here instead are style-guide-aware title case, acronym handling, the code cases, and converting a whole document on any device – including a phone, where Shift+F3 does not exist.

Tips and common mistakes

• Capitalize Each Word is not title case. "The Art Of The Deal" gives itself away with "Of" and "The". Use Title Case with a style selected.
• Short verbs are capitalized. "Is", "Be", "Are" and the pronoun "It" are often wrongly lowercased because they are short; every style guide capitalizes them.
• Pick one style and stay with it. Search engines match queries without regard to case, so capitalization does not change which searches a page can appear for. Consistency across a site matters more than which style you choose.
• Use kebab-case for web file names. macOS and Windows file systems are case-insensitive by default while Linux servers are not, so Hero.png and hero.png are one file locally and two files in production.
• Check ß and dotted i. Uppercasing follows Unicode rules: "straße" becomes "STRASSE", and the result for "i" depends on your browser's language setting, which matters for Turkish text.
• Count as you go. For exact limits such as meta description length, use the character counter or word counter.

Privacy and limitations

All conversions run as JavaScript in your browser; the text is never sent to a server, so the tool is safe for unpublished drafts and client work. Your draft lives in the tab's session storage and disappears when the tab closes; only the title case style and the acronym switch are remembered in local storage.

Known limitations: sentence case cannot recognize ordinary proper nouns; outside APA, title case treats "up", "off", "out", "over" and "down" as adverbs even in the rarer prepositional use ("Over the Hill"), and the noun-or-preposition guess for words like "past" relies on the word before it; "etc." is decided by a fixed rule rather than by meaning; and the code cases keep accented letters, so replace them first if a target system requires plain ASCII. A megabyte of text converts in well under a second on a typical laptop, but the editor may respond slowly while you type in it. If your text has hard line breaks in the wrong places, run it through the line break remover before converting.