Text Case Converter

How Do You Convert Text and Check the Result?

Paste text into Input and click a case button to see it in Converted Output immediately. For a heading, start with the NASA mission: a guide to XML. Leave Keep acronyms checked and space cleanup off. The examples below use the same source so you can compare capitalization and separator changes before copying the result.

One heading converted with Keep acronyms enabled

Button	Converted output
UPPER	THE NASA MISSION: A GUIDE TO XML
Title	The NASA Mission: A Guide To XML
Sentence	The NASA mission: a guide to XML
AP Title	The NASA Mission: a Guide to XML
snake_case	the_nasa_mission:_a_guide_to_xml

The colon survives even in snake_case: developer formats replace selected separators rather than stripping every punctuation mark. The table also shows that AP Title does not automatically capitalize the word after a colon. Review headings and identifiers in their intended context instead of treating conversion as proofreading or syntax validation.

Which Case Formats Are Available?

The 15 buttons are organized into four groups. Basic contains UPPER, lower, Title, and Sentence. Developer contains camelCase, PascalCase, snake_case, kebab-case, CONSTANT, dot.case, and path/case. Style Guide offers AP Title and Chicago. Fun contains aLtErNaTiNg and iNVERSE. Choose a format according to whether you need readable prose, a joined identifier, or a decorative change.

UPPER and lower preserve punctuation and whitespace unless another option changes them first. CONSTANT joins uppercase words with underscores. Alternating case starts with a lowercase ASCII letter and switches case for each subsequent ASCII letter; spaces, numbers, and other characters do not advance the alternation. Inverse toggles characters using Unicode uppercase and lowercase methods. Neither decorative format understands sentence structure.

How Do Title, Sentence, AP Title, and Chicago Differ?

Title capitalizes matched words while keeping punctuation, separators, and spacing. Sentence capitalizes only the first matched word and lowercases later words. It does not restart after a full stop, question mark, or exclamation mark. Leading quotation marks and digits do not prevent the first letter word from being capitalized. Proper names need manual review because the converter has no dictionary of people or places.

Keep acronyms starts enabled and preserves words made entirely of at least two uppercase letters in these four formats. Thus NASA and XML stay uppercase. This also preserves ordinary all-capital words such as HELLO; turn it off when normalizing an entire passage typed in capitals. The option does not preserve internal styling in names such as iPhone, and it does not affect developer formats.

AP Title and Chicago lowercase words from different built-in lists, except the first and last matched words. For example, a walk through the park becomes A Walk Through the Park with AP Title and A Walk through the Park with Chicago. These are list-based approximations, not complete implementations of the AP Stylebook or The Chicago Manual of Style: they do not analyze a word's grammatical role.

How Can You Convert Identifiers Without Losing Separate Lines?

Developer formats split at whitespace, underscores, hyphens, dots, slashes, and ASCII case boundaries. They recognize both a lowercase-to-uppercase transition and an uppercase run before a capitalized word. For example, getUserById becomes get_user_by_id, while XMLParser becomes xml_parser. Digits are not separate word boundaries: version2Value becomes version2value.

Enable Line-by-Line for a list. Input containing first name and last name on separate lines produces separate first_name and last_name entries in snake_case. Without that option, the result is one identifier: first_name_last_name. Blank lines and the original CRLF, LF, or CR separators remain when converting independently. The option also restarts Sentence capitalization and alternating case on each nonempty line.

Convert names rather than complete source files. The tool does not validate identifiers for any programming language, remove all punctuation, or protect quoted strings and comments. Likewise, path/case joins words with slashes; it does not check filesystem rules or create folders.

When Should You Select a Language or Clean Spaces?

Language for UPPER / lower offers Default Unicode, Turkish, Azerbaijani, and Lithuanian. Turkish and Azerbaijani distinguish dotted and dotless I: uppercase i ı becomes İ I, and lowercase I İ becomes ı i. Lithuanian uses locale-aware casing too. The selector affects only UPPER and lower; it does not change Title, Sentence, or identifier conversion.

Clean spaces (keep line breaks) removes indentation and trailing horizontal whitespace from each line and collapses repeated horizontal whitespace, including tabs, to a single space. It retains paragraph separators rather than flattening the document. Leave cleanup off when tab alignment matters. Title already preserves line breaks; Line-by-Line is needed there only if you want each line processed independently, especially for first-and-last-word rules in editorial titles.

In What Order Do Find and Replace and Conversion Run?

Find & Replace applies literal, case-sensitive, non-overlapping replacements first. Space cleanup runs next, followed by the chosen case conversion, optionally per line. Searching for a period therefore matches a period rather than any character. Replacement strings such as $& are inserted literally. An empty Find field changes nothing, and the match count describes the original input.

For example, replace draft with final copy in draft report and choose snake_case: the result is final_copy_report. Closing the panel stops replacements while retaining its field values. The input stays available for comparison. Use Word Counter or Character Counter when reviewing a document's length alongside its capitalization.

What Are the Import, Export, and History Limits?

Import .txt reads one UTF-8 text file locally, up to 5 MiB (5,242,880 bytes). It accepts an optional UTF-8 byte order mark and empty files, but rejects malformed UTF-8 and null characters. Failed imports display an error and keep the previous input. There is no configured character cap for pasting, but conversion runs synchronously, so large documents can slow the page.

Both panels show words, characters, and lines. Words are whitespace-separated chunks; character counts use JavaScript string length, so an emoji may count as more than one character. Download saves converted-text.txt. Swap places the output in Input. History keeps five distinct nonblank snapshots from format changes, Swap, Clear, and imports; ordinary typing is not a complete undo history. Restoring text leaves current options active. Text and history live in memory and are cleared by a page reload.