Case Converter

Change the letter case of pasted or typed text without retyping it. Choose a transformation, check the result and copy it or download a plain-text file.

Input

Text to convert

Up to 100,000 UTF-16 code units, not visible characters. Browser text areas use LF line endings.

Transformation

Letter rules

Result

Enter text and select Convert text.

Converted text

Local conversion

The tool converts your text in your browser without tool-added uploads or saved input history.

Copy and download happen only when requested. Other site services and consent settings remain separate.

Convert your text

Paste or type your text, then choose Uppercase, Lowercase, Capitalize words or Sentence case. Select Turkish/Azerbaijani letter rules when the dotted and dotless forms of I matter.
Select Convert text and review the output. Names, abbreviations and acronyms may need manual editing after a mode that first lowercases the passage.
Copy the result or download it as a UTF-8 text file. If clipboard permission is denied, the result is selected so you can copy it manually. Editing the source or settings removes the old result until you convert again.

What each transformation means

Uppercase and Lowercase convert the whole text using the selected letter rules. A letter can become more than one character: the uppercase form of the German sharp S in Straße gives STRASSE. Changing the case back cannot always recover the original spelling.

Capitalize words first lowercases the text, then uppercases the first cased character in each word recognized by the browser's English word segmenter. It does not apply a publication's title-style rules or keep short words lowercase.

Sentence case first lowercases the text, then uppercases the first cased character and the next one after a full stop, question mark, exclamation mark, ellipsis or line break. Chinese full stops and full-width question/exclamation marks count too. A decimal point between ASCII digits does not start a new sentence. Quotes, numbers and Chinese characters can remain before the next cased letter.

The default letter rules are independent of the page language. Turkish/Azerbaijani rules handle I, İ, ı and i differently. Capitalize words uses the specified English word segmenter; newer characters and word boundaries can differ across browser versions. Sentence case follows the listed punctuation, not a grammar model.

Check the result before using it

Capitalizing hELLO, wORLD! produces Hello, World! Sentence case changes a passage such as WHO ARE YOU? into Who are you? without trying to restore names or acronyms.

With default rules, lowercase I becomes i. With Turkish/Azerbaijani rules, lowercase I becomes dotless ı, and uppercase i becomes dotted İ. Choose the rule for the text rather than relying on the interface language.

Chinese characters, emoji and numbers can remain unchanged while nearby Latin letters change case. An unchanged result is still valid; it does not mean the tool failed.

Mechanical letter changes, not rewriting

Enter up to 100000 UTF-16 code units. Emoji and some other characters use two or more units, so this is not a count of visible characters. The tool reports oversized or malformed input instead of silently cutting it off or replacing broken surrogate sequences.

Capitalize words is not editorial title case or Unicode titlecase mapping. It uppercases word starts after lowercasing, which can expand a letter into several characters. Neither capitalization mode automatically preserves acronyms or correct proper names.

The tool does not import files, rewrite markup, remove accents or detect the writing language. Native browser text areas use LF line endings. Downloads contain the current result as UTF-8 without an added byte-order mark or extra newline. Missing word-segmentation support is explained, not replaced with guessed word rules. Sentence case does not protect abbreviations, URLs or email addresses from letter changes.

Your text

Conversion takes place in your browser. This tool does not add text uploads or save your passage between visits. Copy writes only the result to your clipboard when you request it; downloads are generated locally. Existing site services still follow the site privacy policy.

Case conversion questions

No. It lowercases the passage and uppercases the first cased character of each recognized word. It does not decide which articles, prepositions or proper names should keep a particular style.

Some case mappings expand one character into several, such as ß becoming SS in uppercase. A shorter or longer result is not necessarily an error, and changing the case back may not restore the original.

No. Letter rules are a separate setting, and conversion uses your explicit selection. Changing the interface language does not rewrite the text or silently switch between dotted and dotless I rules.

Chinese characters do not acquire an uppercase form here. They remain in the text while letters with case, such as nearby Latin letters, can change.

It contains the current result encoded as UTF-8, without an added byte-order mark, heading or final newline. A leading byte-order-mark character already present in your own text is preserved as text.

It follows the documented punctuation and line-break rule, not a grammar model or abbreviation dictionary. For example, e.g. this becomes E.G. This. Names, acronyms, URLs and email addresses may need manual corrections.

Sources

Reviewed 4 November 2026. These references explain the method, not a certification of this tool or a browser's Unicode version.

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