The naming conventions and where they belong
Programming languages and platforms each settled on different conventions, and using the wrong one is a quick way to look out of place in a codebase — or, in some systems, to simply not work.
- camelCase — JavaScript and Java variables and functions. First word lowercase, every following word capitalised:
userAccountName. - PascalCase — class and component names in most languages, and React components specifically:
UserAccountName. - snake_case — Python variables and functions, and database column names:
user_account_name. - SCREAMING_SNAKE_CASE — constants and environment variables across nearly every language:
MAX_RETRY_COUNT. - kebab-case — URLs, CSS class names and file names. Search engines read hyphens as word separators and underscores as joiners, which is why URL slugs use hyphens:
user-account-name. - dot.case — configuration keys and namespaced settings:
app.database.host.
Sentence case and title case
Sentence case capitalises only the first letter and anything that was already a proper noun. It is the house style for headings at most technology companies now, because it reads faster and looks less shouty.
Title case capitalises the significant words and leaves short articles, conjunctions and prepositions lowercase — the style used by newspapers and book titles. The version here follows the common convention of lowercasing words like a, the, of, and unless they open the title. Style guides disagree on the details, particularly on prepositions of four or more letters, so check yours if the output matters.
A note on ALL CAPS
Uppercase text is measurably slower to read, because it removes the ascender and descender shapes that let the eye recognise word outlines. It is fine for short labels and buttons, and a poor choice for anything longer than a few words. If you need emphasis in body text, weight or italics does the job without the readability cost.
Converting text that already has a case
Splitting text into words is the hard part of case conversion, not joining it back together. The converter here handles input that arrives already in camelCase, snake_case or kebab-case, so you can paste getUserName and get get_user_name without inserting spaces yourself. Acronym runs like parseHTTPResponse are treated as single words, which is what most style guides expect.
Frequently asked questions
Does it work with Arabic or other non-Latin scripts?
Scripts without letter case — Arabic, Hebrew, Chinese, Japanese — are unaffected by upper and lower conversions, which is correct behaviour. Word splitting for snake_case and kebab-case still works on spaces.
Is my text sent to a server?
No. Conversion happens in your browser and nothing is transmitted or stored.
Why did title case leave some words lowercase?
Title case deliberately keeps short articles, conjunctions and prepositions lowercase unless they are the first word. If you need every word capitalised, use Capitalised Words instead.
Is there a length limit?
No fixed limit. Very long documents may briefly slow the browser while converting, since the whole text is processed at once.