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Case Converter

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Convert letter case and programming naming styles online (camelCase/snake_case)

  1. 1

    Paste text or a list

    Paste text, a variable list, or file names — or click the example to see mixed-input behavior; conversion is real-time.

  2. 2

    Pick mode and batch behavior

    Choose one of the 10 modes; keep line-by-line for lists, turn it off for phrase-to-slug.

  3. 3

    Copy the result

    Copy in one click; character and line counts show below.

Features Overview

Convert letter case online: UPPERCASE, lowercase, Title Case, and Sentence case for text, plus camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, and dot.case for programming names — all in one click. Line-by-line batch conversion for variable lists, consecutive capitals split correctly (HTTPServer to http_server), CJK mixed text preserved, entirely in your browser.

Tool Description

Free online letter case converter with 10 modes: upper, lower, title, sentence, and six programming naming styles. Batch-convert variable and file name lists line by line; consecutive capitals split correctly (HTTPServer to httpServer). All local.

Last updated

Capabilities Checklist

  • 10 modes: four text modes (upper, lower, title, sentence) plus six programming naming styles (camel, Pascal, snake, kebab, constant, dot) covering both text layout and variable naming.
  • Line-by-line batch: variable and file name lists convert independently per line; toggle off to merge the whole input into a single identifier (phrase-to-slug usage).
  • Quality rules: consecutive capitals split correctly (XMLHttpRequest to xml_http_request), digits stick to the preceding word, ALL CAPS input normalizes properly (Title gives All Caps, not unchanged), and words starting with digits like 3rd stay untouched.
  • CJK-friendly: mixed Chinese text is preserved (已获取 user_name 列表 to 已获取_user_name_列表); sentence splitting honors CJK punctuation.
  • Real-time conversion with character and line counts; nothing is uploaded.

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Related Guides

Variable Naming and Letter Case: camelCase, snake_case, and Language Conventions

Why does the same variable look different across languages? This guide covers the conventional boundaries of camelCase, snake_case, PascalCase, and kebab-case, plus the tricky conversion rules — splitting consecutive capitals, digit grouping, CJK mixed text — with each language's built-in case functions and editor shortcuts, ending with batch-converting variable lists online.

Frequently Asked Questions

Which case modes does this tool support?
Ten: UPPERCASE, lowercase, Title Case, and Sentence case for text, plus camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, and dot.case for programming names. Text modes always process line by line; programming modes offer per-line batch or whole-input merge.
What's the rule for consecutive capitals like HTTPServer?
When the last capital of a consecutive run is followed by a lowercase letter, it starts the next word: HTTPServer splits into HTTP + Server, giving http_server in snake_case; XMLHttpRequest gives xml_http_request. Digits stick to the preceding word: parseJSON2x gives parse_json2x. These two inputs quickly test any converter's quality.
How does mixed CJK text convert?
Chinese characters and punctuation are preserved; only Latin letters convert: 已获取 user_name 列表 in snake_case gives 已获取_user_name_列表; in Title Case, hello 中文 world gives Hello 中文 World. Sentence case always splits on the CJK full stop (。), capitalizing a following Latin letter.
What does ALL CAPS input give in Title Case?
All Caps Input: each word's remaining letters are lowercased first, then the first letter capitalized. A tool that only prepends capitals would output ALL CAPS INPUT (i.e., nothing changed). Likewise, words starting with a digit like 3rd stay untouched rather than becoming 3Rd.
What's the difference between line-by-line and whole-input modes?
Batch on (default): each line converts independently — right for variable and file name lists. Batch off: newlines and spaces both act as separators, merging everything into one identifier (multi-line text becomes a single snake_case string) — right for turning phrases into slugs. The four text modes always process line by line regardless.