Case converters change text between uppercase, lowercase, title case, sentence case, camelCase, snake_case, and kebab-case — one click instead of retyping. Writers fix headlines; developers convert between naming conventions for variable, file, and URL formatting; data analysts normalise inconsistent input.

This guide covers the case formats, when each applies, and the small details that catch people out.

Case Formats

  • UPPERCASE — ALL CAPS; emphasis, acronyms
  • lowercase — all lower; informal, URLs, code
  • Title Case — First Letter Of Each Word; headlines, book titles
  • Sentence case — Only first word capitalised; body text, modern UI
  • camelCase — firstWordLowerRestCapped; JavaScript, Java variables
  • PascalCase — EveryWordCapped; class names, C#, components
  • snake_case — words_joined_by_underscores; Python, Ruby
  • kebab-case — words-joined-by-hyphens; URLs, CSS classes
  • CONSTANT_CASE — UPPER_SNAKE; constants, environment variables
  • Toggle case — InVeRtS eXiStInG cAsE

Common Use Cases

  • Standardising headlines for SEO
  • Converting between code naming conventions
  • Cleaning up data with inconsistent casing
  • Generating URL slugs from titles
  • Formatting environment variable names
  • Converting database column names between styles
  • Producing SHOUTING for legal disclaimers

Title Case Variants

"Title Case" has several conventions:

  • AP Style — Capitalise major words; lowercase articles/prepositions under 4 letters
  • Chicago Style — Similar but more nuanced
  • All Caps for All Words — Simplest; less polished

"The Quick Brown Fox Jumps over the Lazy Dog" (AP) vs "The Quick Brown Fox Jumps Over The Lazy Dog" (all words).

Code Naming Conventions by Language

  • JavaScript / TypeScript — camelCase variables, PascalCase classes
  • Python — snake_case variables/functions, PascalCase classes
  • Ruby — snake_case methods, PascalCase classes
  • Go — camelCase or PascalCase based on export visibility
  • Rust — snake_case functions, PascalCase types, CONSTANT_CASE constants
  • HTML/CSS — kebab-case for attributes and classes
  • SQL — snake_case columns (convention varies)
  • Environment variables — CONSTANT_CASE

URL Slugs

  • kebab-case is standard (this-is-a-slug)
  • Lowercase only
  • Strip accents (café → cafe)
  • Replace special characters with hyphens
  • Collapse consecutive hyphens
  • Trim leading/trailing hyphens

Common Pitfalls

  • Title case acronyms. "URL" should stay "URL" not become "Url"
  • Proper nouns lowercased. Brand names like "iPhone" need preservation
  • Accent stripping in URLs. Décor → decor; ensure intentional
  • camelCase to snake_case. "JSONParser" → "j_s_o_n_parser" without smart handling
  • Mixed separators. "my-file_name" inconsistent; pick one
  • Locale-specific casing. Turkish I/İ rules differ from English

For Specific Tasks

Generating URL Slugs

Lowercase → strip accents → replace non-alphanumeric with hyphen → collapse hyphens.

API Response Conversion

Convert snake_case JSON keys to camelCase for JavaScript clients.

Headline Formatting

Title case for SEO titles; sentence case for body subheadings; consistent within a site.

Variable Renaming

Convert between conventions when porting code between languages.

Quick Tips

  • Pick a convention per project and stick to it
  • Title case for titles; sentence case for body
  • kebab-case for URLs and CSS
  • Watch acronyms and proper nouns; manual fix after auto-convert
  • For SEO, consistent casing across titles improves polish

Use the Case Converter on Popupnote

The Case Converter on Popupnote provides a clean tool for converting text between upper, lower, title, sentence, camel, snake, kebab, and constant case — for writers, developers, and anyone working with text formatting. The tool runs in your browser without any account required.