Case Converter

Convert text into twelve writing and developer case formats at once. Unicode-aware results stay private in your browser.

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What a Case Converter Does

A case converter changes the casing or naming structure of text without requiring you to retype it. TextCraftHub calculates five writing-oriented results and seven developer-oriented results at the same time, so you can compare them before copying the one you need.

Writing conversions retain punctuation, spacing, line endings, emoji, and uncased scripts. Developer conversions identify reusable word tokens, normalize source separators and identifier boundaries, and preserve each physical line as a separate conversion unit.

Writing Case Formats

These formats preserve the layout of the source text. Title and sentence detection use documented, conservative heuristics rather than claiming complete editorial or grammatical analysis.

UPPERCASE

Uses Unicode-default uppercase mappings unless an explicit locale is supplied. Some mappings can expand into more than one character.

lowercase

Uses Unicode-default lowercase mappings while retaining punctuation, emoji, whitespace, and exact line endings.

Title Case

Capitalizes title words, keeps common English small words lowercase in ordinary positions, and preserves source-uppercase entries from the built-in acronym list.

Sentence case

Lowercases ordinary cased prose and capitalizes detected sentence beginnings while protecting URLs, email addresses, and built-in acronyms.

Toggle Case

Swaps uppercase and lowercase mappings code point by code point. Uncased characters remain unchanged.

Developer Naming Conventions

Developer formats use one shared Unicode-aware tokenization pass. They normalize source acronyms rather than applying the writing acronym list.

camelCase

helloWorld

PascalCase

HelloWorld

snake_case

hello_world

CONSTANT_CASE

HELLO_WORLD

kebab-case

hello-world

dot.case

hello.world

path/case

hello/world

How Words Are Identified for Developer Conversions

The shared Developer Identifier Tokenizer recognizes Unicode letters, combining marks, and numbers. Whitespace, underscores, hyphens, dots, slashes, punctuation, symbols, apostrophes, and emoji act as separators. Repeated separators collapse instead of creating empty identifier parts.

Existing identifier boundaries are also recognized: helloWorld splits before World, XMLParser splits into XML and Parser, and version2Update splits at both number boundaries. Each source line is tokenized once, and the same immutable token structure feeds all seven developer outputs.

CRLF, LF, and lone CR line endings are preserved exactly. Every physical line is converted independently, including blank lines and a final trailing line break.

Unicode and Language Behavior

Default writing results use Unicode case mappings without forcing an English locale. An optional internal locale can tailor casing for language-specific behavior such as Turkish dotted and dotless I, but the MVP does not expose a locale selector.

Scripts without uppercase and lowercase forms, including Hindi, Arabic, Chinese, and Japanese, generally remain unchanged in writing results. Developer formats retain their word tokens without transliteration. Emoji, flags, skin tones, and joined emoji sequences are preserved in writing formats and treated as separators for identifiers.

When Case Conversion Can Alter Character Length

Case mapping is not always a one-to-one replacement. The default uppercase form of German ß expands to SS, and other Unicode mappings can also add or rearrange code points. Lowercasing and uppercasing are therefore not guaranteed to preserve length or round-trip to the original string.

The editor limit applies to the source text. A transformed result may be slightly longer than the accepted source because of legitimate Unicode mappings, and Copy uses that complete transformed value.

Common Case-Conversion Mistakes

Assuming every title rule is the same

Editorial styles disagree about small words, punctuation, and capitalization. This tool documents its own restrained heuristic instead of claiming a named style.

Treating every uppercase word as an acronym

Preserving all short uppercase words would also preserve ordinary shouting. Only source-uppercase entries from the small built-in list are protected.

Using prose rules for identifiers

camelCase and snake_case need token boundaries and separators, not title grammar. Developer formats use a separate shared tokenizer.

Expecting equal input and output lengths

Unicode mappings can expand, and developer separators can be removed or replaced. Validate destination limits after conversion.

Case Converter content review

Last reviewed: July 2026

Technical review: Lalit Giani

Case mappings follow Unicode and ECMAScript behavior, with explicit locale tailoring available through the internal API. TextCraftHub's English title heuristic, fixed abbreviation set, built-in acronym list, and developer identifier rules are documented product choices rather than Unicode standards.

Verified facts

Default case mappings: Uppercase and lowercase results use ECMAScript's Unicode default case conversion when no locale is supplied. [3] [1]
Locale-sensitive casing: An explicitly supplied locale can tailor case mappings for language-specific conventions such as Turkish dotted and dotless I. [4] [2]
Length-changing mappings: A case mapping can produce multiple code points, so converted strings are not guaranteed to retain their source length or round-trip symmetrically. [1] [2]
Uncased text: Characters without uppercase or lowercase mappings map to themselves during default case conversion. [1]
Local processing: Text entered into Case Converter is transformed in the browser and is not stored or transmitted by the utility. [5]

Sources

1. The Unicode Standard, Chapter 5: Case Mappings - Unicode ConsortiumReferenced July 2026
2. Unicode Character Database: SpecialCasing - Unicode ConsortiumReferenced July 2026
3. ECMAScript String case conversion specification - Ecma InternationalReferenced July 2026
4. ECMA-402 locale-sensitive String case conversion - Ecma InternationalReferenced July 2026
5. TextCraftHub Privacy Policy - TextCraftHubVerified July 2026

Editorial Policy · Sources and References

Case Converter FAQ

Is entered text uploaded or stored?

No. Editing and all twelve conversions happen in your browser. The Case Converter does not send the text to a TextCraftHub server or add persistent history, cloud storage, or account storage.

What is the difference between Title Case and Sentence case?

Title Case capitalizes eligible title words and keeps documented small words lowercase in common positions. Sentence case lowercases ordinary cased text and capitalizes the beginning of detected sentences. Both use documented heuristics rather than complete grammatical analysis.

What is camelCase?

camelCase joins identifier words without separators, keeps the first word lowercase, and capitalizes each later word, as in caseConverterResult.

What is PascalCase?

PascalCase joins identifier words without separators and capitalizes every word, as in CaseConverterResult. It is often used for type, class, and component names.

What is snake_case?

snake_case joins normalized lowercase words with underscores. It is commonly used for variables, database fields, filenames, and configuration keys depending on a project's conventions.

What is kebab-case?

kebab-case joins normalized lowercase words with hyphens. It is widely used in URLs, CSS class names, package names, and filenames, although each system can impose additional rules.

What is CONSTANT_CASE?

CONSTANT_CASE joins uppercase words with underscores. It is a naming convention often used for constants and environment variables, not a Unicode standard.

Does Case Converter work with Unicode?

Yes. It uses JavaScript's Unicode-aware casing and Unicode property-based tokenization. Accented Latin, Greek, Cyrillic, combining marks, and uncased scripts are preserved according to the documented rules.

Why do some letters change length when converted?

Unicode case mappings are not always one character to one character. For example, the default uppercase mapping of German sharp s can expand to SS, so a converted result can contain a different number of code points or UTF-16 units.

Will emoji or Hindi text be changed?

Emoji and Hindi characters do not have uppercase/lowercase mappings, so writing transformations generally leave them unchanged. Developer formats keep Hindi word tokens but use separators or joins according to the selected naming convention; emoji acts as a separator there.

Does Title Case follow AP or Chicago style?

No. TextCraftHub uses a documented English small-word heuristic. It does not claim complete compatibility with AP, Chicago, MLA, or another editorial style guide.

Can it preserve acronyms such as API, NASA, or HTML?

Title Case and Sentence case preserve source-uppercase entries from the built-in acronym list: API, HTML, CSS, JSON, XML, HTTP, HTTPS, URL, URI, SQL, NASA, SEO, AI, UI, UX, PDF, CSV, USB. The list is intentionally small, mixed-case spellings are not promoted, and unlisted uppercase prose is normalized. Developer cases always normalize acronym tokens.

How is punctuation handled?

Writing cases retain punctuation and spacing. Sentence case uses a fixed conservative abbreviation list and best-effort sentence endings. Developer cases treat punctuation, symbols, whitespace, and emoji as token separators while preserving physical line endings.

Can large text be converted?

Yes, up to 100,000 Unicode code points. Cards show a grapheme-safe preview for large results, Show full result can reveal one complete output at a time, and Copy always uses the complete in-memory result.