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ToolNimbly

Case Converter

Ten casing conventions, applied without destroying your original text.

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What this tool does

Convert text between ten conventions: lowercase, UPPERCASE, Sentence case, Title Case, camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE and alternating case. Your original stays in place next to the result, so a conversion is never a one-way door. Locale-aware casing is supported, which matters for Turkish dotted and dotless i and for German sharp s — the cases where a naive uppercase transformation produces the wrong word.

How to use this tool

  1. Step 1: Paste your text

    The original is preserved in its own field and is not modified by any conversion.

  2. Step 2: Choose a case

    Each option shows a live preview of the result, so you can see what a convention does before committing to it.

  3. Step 3: Set the locale if it matters

    Defaults to your browser locale. Change it when converting Turkish, Azerbaijani, Lithuanian or German text, where casing rules differ from the default.

  4. Step 4: Copy or download the result

    Copy to the clipboard or save the converted text as a file. The original remains untouched either way.

Worked example

One phrase in every convention

Starting from: user profile image URL

lowercase
user profile image url
UPPERCASE
USER PROFILE IMAGE URL
Sentence case
User profile image url
Title Case
User Profile Image URL
camelCase
userProfileImageUrl
PascalCase
UserProfileImageUrl
snake_case
user_profile_image_url
kebab-case
user-profile-image-url
CONSTANT_CASE
USER_PROFILE_IMAGE_URL

The programming conventions collapse whitespace and punctuation into a single separator, which is why they are safe for identifiers and filenames but lossy for prose.

How each conversion works

Prose conversions change letter casing and leave the structure alone. Identifier conversions first split the text into words at spaces, punctuation and existing case boundaries, then rejoin them with the target separator.

lowercase / UPPERCASE   locale-aware casing, structure untouched
Sentence case           first letter of each sentence capitalised
Title Case              each word capitalised, minor words lowercased
camelCase               words joined, first word lowercase
PascalCase              words joined, every word capitalised
snake_case              words joined with underscores, lowercased
kebab-case              words joined with hyphens, lowercased
CONSTANT_CASE           words joined with underscores, uppercased
alternating case        letters alternate, non-letters skipped
  • Alternating case is deterministic: it starts lowercase and only advances the alternation on letters, so the same input always produces the same output regardless of punctuation.
  • Locale selection matters more than it looks. In Turkish, uppercasing "i" gives "İ" rather than "I", and the default locale gets that wrong.
  • Digits and emoji pass through the identifier conversions unchanged, and are treated as word boundaries where that is the sensible reading.

Sources and methodology

ToolNimbly performs this work locally in your browser using the method shown above. Read how ToolNimbly tests calculations and generated documents.

Case conversion needs word-boundary rules

Changing every letter to upper- or lowercase is straightforward. Converting to camelCase, snake_case or title case first requires deciding where words begin and end. Spaces and punctuation are obvious separators, but existing capitals, numbers, acronyms and non-Latin scripts create ambiguous cases. “XMLHttpRequest” might be read as XML, Http and Request or as several individual capitals depending on the algorithm.

Title case is a style decision rather than a universal transformation. Editorial styles disagree about short articles, prepositions and the first word after a colon. Code-oriented formats are stricter, but changing an identifier’s case can still break a reference in a case-sensitive language or file system. Treat the output as an editable draft, especially for names, acronyms and program identifiers, and compare it with the conventions of the destination system.

Limitations and privacy

What this tool does not do

  • Title Case uses a documented list of minor words. It cannot know that a particular word is a proper noun, a brand name or part of a quoted title, so editorial review is still needed.
  • Sentence case relies on sentence detection, which can be fooled by abbreviations like "Dr." or "e.g." and by decimal points inside numbers.
  • The identifier conversions are lossy. Converting to snake_case and back will not restore the original punctuation or capitalisation.
  • Acronyms are handled by convention rather than knowledge: "URL" becomes "Url" in PascalCase, which some style guides prefer and others do not.

All conversion happens in your browser. Neither the original nor the converted text is uploaded, stored or logged.

Frequently asked questions

What is the difference between Title Case and Sentence case?

Title Case capitalises most words in a heading, leaving short articles, conjunctions and prepositions lowercase unless they start or end the title. Sentence case capitalises only the first word of each sentence, plus any proper nouns that were already capitalised.

When should I use camelCase rather than snake_case?

It is a convention, not a rule, and it follows the language. JavaScript, Java and C# lean camelCase and PascalCase; Python, Ruby and SQL lean snake_case; CSS classes and URL slugs use kebab-case. Match whatever the surrounding code already does.

Why does the locale setting matter?

Because casing is language-specific. The best-known example is Turkish, where lowercase "i" uppercases to "İ" and the dotless "ı" uppercases to "I". Using the wrong locale there produces a different word, not just different styling.

Will converting my text lose anything?

The prose conversions preserve everything except letter casing. The identifier conversions deliberately discard spacing and punctuation, so they are lossy — which is why the original text stays on screen next to the result.

How does alternating case treat punctuation and numbers?

It skips them. The alternation only advances on letters, so a space or a comma does not flip the pattern. This makes the output deterministic and repeatable, which a naive position-based implementation is not.

Read more about this

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Part of Text & Developer Tools. Last reviewed .