Last updated 3 September 2026
Which case should you use
- UPPERCASE — shouting, acronyms, or short labels. Hard to read in long runs.
- lowercase — stripping formatting back before you re-case, or for a deliberately casual tone.
- Title Case — headings and titles. Every word starts with a capital.
- Sentence case — ordinary prose. Only the first letter of each sentence is capitalised.
- camelCase — variables and function names in JavaScript, Java and similar languages.
- PascalCase — class and component names in most languages.
- snake_case — Python variables, database columns, environment names.
- kebab-case — URLs, CSS class names, file names.
- aLtErNaTiNg — the mocking-tone meme format. It has exactly one use, and you know it when you need it.
The cases developers actually need
Beyond sentence case and title case, most of the conversions here exist because programming languages and file systems disagree about word separators. camelCase is the convention in JavaScript and Java for variables. PascalCase, the same thing with a capital first letter, is used for classes and React components. snake_case dominates Python and SQL column names. kebab-case is what CSS classes, URLs and filenames use, because a hyphen is safe in all three where an underscore or a space is not.
Converting between them by hand across a long list is where mistakes creep in — a single missed capital in a column name is a runtime error rather than a warning. Pasting the list in and converting the whole block at once removes that class of mistake entirely.
What title case actually means
There is no single correct answer here, which is why automatic title casing sometimes looks wrong. Style guides disagree about which words stay lowercase: most keep articles, short prepositions and conjunctions down unless they begin or end the title, but the cutoff for "short" varies between three, four and five letters depending on whether you follow AP, Chicago or a house style.
The practical approach is to convert first and then read the result, rather than trusting any tool blindly. Proper nouns, acronyms and brand names with deliberate lowercase styling will always need a manual pass — no rule set can tell that iPhone should not become IPhone.
Common questions
What is the difference between Title Case and Sentence case?
Title Case capitalises the first letter of every word — good for headings. Sentence case capitalises only the first letter of each sentence, leaving the rest lowercase — which is how ordinary prose is written.
What are camelCase, PascalCase, snake_case and kebab-case for?
They are naming conventions used in code. camelCase and PascalCase are common for variables and classes, snake_case is common in Python and database columns, and kebab-case is used in URLs, CSS class names and file names.
Is my text sent anywhere?
No. Every conversion runs in your browser. Nothing is uploaded, logged or stored, and the text disappears when you close the page.
What is the difference between camelCase and PascalCase?
Only the first letter. camelCase starts lowercase and is conventionally used for variables and functions; PascalCase capitalises the first letter too and is used for classes, types and React components. Everything after the first word is capitalised in both.
Why should filenames use kebab-case?
Hyphens are safe in URLs, in file systems and in CSS class names, so one convention works everywhere. Spaces get percent-encoded into %20 in addresses, and underscores are visually hidden by link underlining, which makes hyphens the safer default for anything that might end up in a web address.
Why did the title case output capitalise a word I expected to stay lowercase?
Style guides disagree on which short words stay down, and where the length cutoff sits. Automatic title casing applies one consistent rule set, so proper nouns, acronyms and deliberately lowercase brand names will always need a quick manual check afterwards.