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Case Converter

Switch text between eleven capitalisation styles, from Sentence case to CONSTANT_CASE.

Result
chars
43
words
9
lines
1
size
43 B
The Quick Brown Fox Jumps Over the Lazy Dog

  • Nothing is uploaded

    Everything runs in your browser. Your text never reaches a server.

  • Up to 100,000 repeats

    Ten times the usual ceiling, and it stays responsive at the top end.

  • Any language, any emoji

    Full Unicode support, with emoji counted as single characters.

  • Copy or download

    One click to the clipboard, or save the whole result as a .txt file.

Retyping a heading because it arrived in the wrong capitalisation wastes a minute you will spend again tomorrow. Paste the text, choose a style, and the converted version appears beside it. Eleven styles are available, covering everyday writing, programming identifiers and the two playful ones that people use in captions and chat.

The everyday styles are UPPERCASE, lowercase, Title Case and Sentence case. The programming styles are camelCase, PascalCase, snake_case, kebab-case and CONSTANT_CASE. The last two, aLtErNaTiNg and iNVERSE, flip capitals for effect. Switching is non-destructive here: your original stays in the input box, so you can try several before you commit.

Three steps

How to use the case converter

  1. 1

    Paste your text

    Anything from a single label to a page of copy. The existing capitalisation does not matter, because each style is rebuilt from the words rather than patched over whatever was there before.

  2. 2

    Pick a style

    Choose from the eleven options. Sentence case is the one to reach for after rescuing a paragraph that someone typed with the caps lock key still switched on.

  3. 3

    Copy it out

    One click copies the converted text. The input stays where it is, so you can turn the same source into a heading, a URL slug and a variable name without pasting it again.

The eleven styles and where each belongs

Choosing a case style is mostly about the destination. Prose follows the conventions of the language and the publication; code follows the conventions of the language and the team. Getting it wrong is rarely fatal, but inconsistent capitalisation across a set of headings or a set of variable names is noticed almost immediately.

  • UPPERCASE and lowercase: shouting or flattening, useful for normalising data before a comparison.
  • Title Case: a capital on every word, the usual choice for English headlines and headings.
  • Sentence case: one capital at the start of each sentence, the default for body copy and UI labels.
  • camelCase and PascalCase: joined words for variables and class names in JavaScript, Java and C#.
  • snake_case and kebab-case: underscores or hyphens, standard for Python names, URLs and CSS classes.
  • CONSTANT_CASE: uppercase with underscores, conventional for environment variables and fixed values.
  • aLtErNaTiNg and iNVERSE: decorative styles for captions, not for anything that must be read carefully.

Where Title Case gets complicated

English style guides disagree about which words to capitalise. Most agree on capitalising nouns, verbs and adjectives while leaving short articles, conjunctions and prepositions in lower case, but they differ on where the cut-off falls and how to treat the final word. The conversion here simply capitalises the first letter of every word.

That means proper nouns, acronyms and product names may need a manual fix afterwards. NASA becomes Nasa, iPhone becomes Iphone, and a surname such as McDonald loses its inner capital. Convert first, then correct the handful of words that carry their own rules, which is still far quicker than retyping the whole line.

Normalising data with case conversion

Case is also a data-cleaning tool. Email addresses, country codes and tags collected from different sources often differ only in capitalisation, and comparing them as they are produces false mismatches. Lowercasing everything before a comparison is a standard first step, and pairing it with duplicate removal usually shrinks a merged list more than people expect.

Turkish is the well-known exception. Its dotted and dotless i do not map onto English rules, so a naive lowercase can change the meaning of a word. The conversion uses your browser's Unicode case mapping, which handles most alphabets correctly, but always check results in a language whose casing rules you do not know.

Frequently asked questions

What is the difference between Title Case and Sentence case?

Title Case puts a capital on each word, which suits headlines and headings. Sentence case capitalises only the first word of each sentence, plus proper nouns, and is easier to read in long text. Most style guides now prefer Sentence case for interface labels and subheadings.

Which case should I use in a URL?

kebab-case. Lowercase words separated by hyphens are the convention for web addresses, because hyphens read as word separators, underscores do not always, and some servers treat uppercase and lowercase paths as different pages. Convert your heading to kebab-case and you have the slug.

Does the converter fix acronyms?

No, and that is deliberate. It cannot tell an acronym from an ordinary word, so USA in a Title Case conversion comes out as Usa. Run the conversion first, then correct acronyms, brand names and inner capitals afterwards; there are usually only a few of them per paragraph.

What happens to numbers and punctuation?

They pass through unchanged in the everyday styles. In the programming styles they are treated as part of a word, so a heading containing 2026 keeps the digits and joins them to the surrounding text: report2026, report_2026 or REPORT_2026, depending on the style you picked.

Can I convert a whole list at once?

Yes. Paste as many lines as you like and every line is converted with the same style, keeping the line breaks intact. That makes it a quick way to standardise a column of names, a set of CSS class names or a batch of headings copied out of a document.

Does it work with accented and non-Latin letters?

Mostly. Case mapping comes from the browser's Unicode implementation, so accented Latin, Greek and Cyrillic convert correctly. Scripts without letter case, such as Arabic, Hebrew, Chinese and Japanese, are left alone. Turkish is the main language where the standard mapping can produce the wrong letter.

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Last updated 23 August 2026