Text Case Converter

Every case this tool supports

• UPPERCASE — every letter capitalised. Useful for short labels and acronyms, but avoid it for whole sentences: uniform letter shapes remove the word outlines readers rely on, which measurably slows reading.
• lowercase — every letter reduced. The usual first step before normalising text for comparison or search.
• Title Case — significant words capitalised, short articles and prepositions left alone. The standard for headlines and book titles.
• Sentence case — only the first word of each sentence capitalised. What most body copy and modern web headings use.
• camelCase — words joined, each after the first capitalised. Variables and functions in JavaScript, Java and C#.
• PascalCase — as camelCase but with the first word capitalised too. Class and component names.
• snake_case — lowercase words joined by underscores. Python variables, and most SQL column names.
• kebab-case — lowercase words joined by hyphens. URLs, CSS class names and file names.
• CONSTANT_CASE — uppercase words joined by underscores. Environment variables and compile-time constants.
• aLtErNaTiNg — alternating capitals, used online to mark sarcasm.

How title case is decided

Title case is not a single rule; it is a family of house styles that disagree at the edges. The version here follows the widely shared core: capitalise every word except short articles, coordinating conjunctions and prepositions — a, an, the, and, or, but, of, in, on, to and their siblings — and always capitalise the first and last word regardless.

So the art of war becomes The Art of War: the leading the is capitalised because it opens the title, while of stays lowercase in the middle. Where style guides differ most is prepositions of four or more letters — Chicago lowercases with and from, AP capitalises them — so check longer prepositions by hand if you are writing to a specific guide.

How camelCase and snake_case are detected

Converting to a programming case first has to work out where the words are. Punctuation, spaces and underscores are obvious boundaries, but the interesting case is an existing identifier with no separators at all.

The converter splits on the transition from a lowercase letter or digit to an uppercase one, and also handles runs of capitals correctly. That second rule is what makes parseHTMLString become parse_html_string rather than the mangled parse_h_t_m_l_string that a naive split produces. Acronyms are the usual reason a case converter fails, so it is worth testing any tool with one before trusting it on a codebase.

What conversion cannot undo

Case conversion loses information in one direction. Once text has been lowercased, nothing in the result records that apple was originally Apple the company rather than the fruit, so converting back to title case will capitalise every significant word indiscriminately.

The same applies to proper nouns in sentence case: I visited Paris in March lowercased and then converted back becomes I visited paris in march. Keep your original text — it stays in the input box here — and always read the result before using it.

Everything runs locally

The conversion happens in your browser as you type. Nothing is uploaded or stored, so pasting unpublished copy, internal documentation or client material carries no risk of it being retained anywhere.