Case Converter Online

What is a case converter?

A case converter is an online tool that changes the capitalisation pattern of text. Instead of retyping content or editing it manually — which is slow and introduces errors — a case converter applies the transformation automatically and consistently across every word. The SmartWriteTools case converter supports eleven conversion modes covering everything from basic capitalisation changes to programming naming conventions.

The eleven case formats explained

Each capitalisation style has a specific use case. Here is a clear reference for all eleven formats in the case converter.

UPPERCASE

Every letter is capitalised. Used in design and print for emphasis, acronyms, and labels. Also used in programming for constants: MAX_RETRY_COUNT. Use sparingly in running text — all caps is harder to read at length and can feel like shouting.

lowercase

Every letter is in lowercase. Used in URL slugs, hashtags, and informal digital contexts. Also the starting point for many programming case conventions.

Title Case

The first letter of major words is capitalised. Minor words — articles (a, an, the), coordinating conjunctions (and, but, or, nor), and short prepositions (in, on, at, by, to, of) — are kept lowercase unless they appear as the first word. This is the standard format for book titles, article headings, film titles, and product names.

Sentence case

The first letter of each sentence is capitalised, and everything else is lowercase (except proper nouns, which you correct manually). This is the standard format for body text in English — the case you use when writing a normal paragraph.

camelCase

The first word is all lowercase. Every subsequent word starts with a capital. No spaces or separators. Used in: JavaScript variable and function names, Java, Swift, and JSON property names.

PascalCase

Every word starts with a capital, including the first. Also called UpperCamelCase. Used for: class names in most object-oriented languages (Python, Java, C#, JavaScript), React component names, and TypeScript interfaces.

snake_case

Words are joined with underscores, all lowercase. Used in: Python variables and functions, Ruby, database column names, file names in many systems. Sometimes called pothole_case.

kebab-case

Words are joined with hyphens, all lowercase. Used in: CSS class names, HTML attributes, URL slugs, and configuration file keys. Also called spinal-case or lisp-case.

CONSTANT_CASE

All uppercase with underscores. The standard convention for named constants in most programming languages: MAX_FILE_SIZE, DEFAULT_TIMEOUT_MS. Also called SCREAMING_SNAKE_CASE.

tOGGLE cASE

The case of every individual letter is inverted — lowercase becomes uppercase and vice versa. Primarily used for stylistic effect or to undo an accidental Caps Lock. Rarely used in formal writing.

AlTeRnAtInG cAsE

Letters alternate between uppercase and lowercase, starting with uppercase. Used as a stylistic or mocking tone device in informal digital communication. Not appropriate for professional writing.

Which case format should you use?

The right choice depends entirely on the context.

How to use the SmartWriteTools case converter

1. Open the SmartWriteTools toolkit and scroll to the Case Converter card
2. Click Run → to expand the tool
3. Type or paste your text into the input field
4. Click any of the eleven case format buttons
5. The converted result appears immediately below
6. Click Copy result to copy it to your clipboard
7. Or click Apply to editor ↑ to send the converted text to the main editor for further analysis

You can switch between formats by clicking different buttons — each click converts the original input text afresh, so you are always comparing against your starting text rather than a chain of conversions. The Clear button resets everything.

Case converter for writing vs programming

Most people who search for a case converter online fall into two groups: writers who need to fix capitalisation in copy, and developers who need to convert variable names or identifiers between naming conventions.

For writers, Title Case and Sentence case are the most commonly used formats. These are straightforward but error-prone to apply manually across a long list of headings or items. A case converter handles them consistently in one step.

For developers, the case converter is most useful when adapting content between contexts — for example, converting a set of field labels from Title Case to snake_case for a database schema, or converting API response keys from snake_case to camelCase for a JavaScript front end. The case converter does this without requiring a script or manual editing.

Privacy and data handling

The SmartWriteTools case converter runs entirely in your browser. Your text is never sent to a server, stored, or logged. This matters if you are converting confidential content — internal document titles, proprietary variable names, or sensitive copy. Nothing leaves your device.