Retyping a heading because it came out in the wrong case, or renaming a variable by hand letter by letter, is the kind of small friction that’s worth automating away entirely. The converter above runs every common case conversion on the same input at once, entirely in the browser — nothing is sent anywhere.

The nine cases

• UPPERCASE — every letter capitalized. Used sparingly in prose (it reads as shouting), but standard for constants in code: MAX_RETRIES.
• lowercase — every letter lowercase. The safe default for slugs, filenames, and most identifiers.
• Title Case — major words capitalized, minor words (a, the, of, in…) lowercase unless they open or close the title. The convention headlines and book titles use.
• Sentence case — only the first letter of each sentence capitalized. What most body text and UI labels should actually be in.
• camelCase — no spaces, each word after the first capitalized. JavaScript and Java variable and function names.
• PascalCase — no spaces, every word capitalized. Class and component names: UserProfile.
• snake_case — lowercase, underscores between words. Python variable names, database columns, many config keys.
• kebab-case — lowercase, hyphens between words. URL slugs, CSS class names, HTML attributes.
• aLtErNaTiNg CaSe — case flips letter by letter. No technical use — the internet’s sarcasm font.

Title Case is the one people get wrong

The naive version — capitalize every word — produces “The Lord Of The Rings,” which no style guide actually recommends. The convention every major style guide (AP, Chicago, APA) converges on keeps short function words — a, an, the, and, but, or, for, nor, at, by, in, of, on, to, up— lowercase in the middle of a title, while always capitalizing the first and last word regardless: “A Tale of Two Cities,” not “A Tale Of Two Cities.” That’s the rule this converter follows.

Where each case actually gets used

• An SEO-friendly URL slug is kebab-case, always lowercase.
• A CSS custom property or Sass variable is typically kebab-case: --primary-color.
• An environment variable is UPPERCASE snake_case: DATABASE_URL.
• A React component file and its export are PascalCase: UserCard.tsx.
• A page <title> or a blog headline is Title Case (or Sentence case, by house style — both are common, pick one and stay consistent).

Frequently asked

Does this tool store or send my text anywhere?

No. Every conversion runs in your browser with plain JavaScript — nothing is uploaded, logged, or sent to a server.

Why does Title Case capitalize a short word sometimes and not others?

The first and last word of a title are always capitalized regardless of length — “ToKill a Mockingbird” capitalizes “To” because it opens the title, while the same word mid-title (“A Guide to Style”) stays lowercase.

What’s the difference between snake_case and kebab-case?

Only the separator — underscore versus hyphen. Which one is correct depends entirely on where it’s used: most programming languages accept underscores in identifiers but not hyphens (a hyphen reads as subtraction), while URLs and CSS conventionally use hyphens.