The Free Case Converter Guide: Uppercase to Lowercase, Title Case, camelCase and What Every Button Really Does
A paragraph typed with Caps Lock on. A headline you are unsure how to capitalise. A spreadsheet header that must become a variable name. All the same small job, and a good case converter does it in the time it takes to paste. This guide shows how to convert case with the tool above, from uppercase to lowercase and lowercase to uppercase through to a title case converter and a sentence case converter for writing, and the naming conventions developers use. It also says exactly what each option does to your words, and where to check the result.
1. What a Case Converter Does: All 18 Options
A case converter rewrites the capitals in a piece of text by a rule, so you never retype it. This one is a text case converter online free of accounts and limits, with eighteen options on one row of buttons. They fall into four families.
For writing
UPPERCASE, lowercase, Title Case, Sentence case and Capitalized Case. The last one is the quickest way to capitalize first letter of each word online, which suits lists of names, product lines and table headings.
For code and the web
camelCase, PascalCase, snake_case, kebab-case, CONSTANT_CASE, dot.case, path/case, Train-Case and Slug (url-safe). Each joins your words into one name.
For fun
aLtErNaTiNg makes this an alternating caps generator SpongeBob mocking text fans will recognise. InVeRsE cAsE flips every letter, and Reverse is a reverse text generator for puzzles, jokes and testing.
For cleaning
Remove extra spaces collapses doubled spaces and tabs and trims line ends, keeping blank lines.
2. How to Convert Case in Three Steps
- Add your text. Paste or type into the Text box, or drop a .txt or .md file onto the panel above it. A dropped file replaces whatever was in the box.
- Pick a case. Title Case is selected to begin with. Click another and the Result box changes immediately, and again with every keystroke.
- Copy or download. Press Copy to put the result on your clipboard, or Download to save it as converted.txt. Your original stays in the Text box.
The page works the same on a phone, where keyboards have no change-case command. To change text case on iPhone or Android, copy the text, paste it here, pick a case and copy it back.
3. Title Case and Sentence Case: The Exact Rules
If you are wondering how to make a title in title case, the common convention is to capitalise the important words and leave short connecting words lowercase. Our Title Case capitalises the first letter of every word except this fixed list, which stays lowercase unless it is the very first word of the text: a, an, the, and, but, or, nor, for, so, yet, at, by, in, of, on, to, up, as, vs, via, per. So “the art of war” becomes “The Art of War”.
Why is my title case wrong? Usually for one of three reasons:
- Acronyms and brand names are flattened. Every word outside the small-word list gets one capital and the rest lowercase, so NASA becomes Nasa and iPhone becomes Iphone. There is no exceptions list, so fix these by hand afterwards.
- It follows no named style guide. AP, APA, Chicago and MLA each have their own rules. This tool does not capitalise the last word or the word after a colon, both of which several guides require, so “what to look out for” ends with a lowercase “for”.
- Only the start of the whole text counts as a start. If you convert several headings at once, a line beginning with “the” or “a” keeps it lowercase. Convert headings one at a time.
Sentence case lowercases everything first, then capitalises the first letter of the text, of each new line, and each word after . ! or ? plus a space. Ideal for shouty text, but proper nouns and the pronoun “I” come out lowercase, and an abbreviation such as “e.g.” can trigger a capital where you did not want one.
Check before you paste. After Title Case or Sentence case, scan for names of people and places, acronyms, brand names with unusual capitals, the word “I”, and the last word of a headline.
4. camelCase vs snake case vs kebab case
The camelcase vs snake case vs kebab case question is mostly about where a name will live:
- camelCase (userFirstName) for variables and most JSON fields. The tool is a camelcase converter for any phrase or identifier.
- PascalCase (UserProfileCard) for types and components. Use it as a pascal case converter for class names: type the phrase, copy the name.
- snake_case (user_first_name) for Python functions and database columns. The Python style guide, PEP 8, recommends it alongside UPPER_CASE constants.
- CONSTANT_CASE (MAX_RETRY_COUNT) for constants and environment variables. Pick it and you have a constant case converter screaming snake case back at you.
- kebab-case (main-nav-item) for CSS class names, file names and web addresses. Use it as a kebab case converter and Train-Case when each word needs a capital.
How to convert camelCase to snake case: paste the camelCase name and choose snake_case. The tool splits words at every lowercase-to-capital hump and at acronym boundaries, so XMLHttpRequest becomes xml_http_request. It also splits on any character that is not a letter or digit, which makes it a reliable snake case converter when you need to convert column names to snake_case: “Order Date (UTC)” becomes order_date_utc. Two cautions: apostrophes are dropped, so “don’t” becomes don_t, and several lines collapse into one name. Convert one header at a time, or use line tools for work that goes line by line.
Slug (url-safe) is the slug generator for a web address. To convert blog title to URL slug without accents, paste the title and pick Slug: “Café Crème Recipes” becomes cafe-creme-recipes. Accents are separated from their letters by standard Unicode normalisation and removed, then anything outside a to z and 0 to 9 becomes a hyphen. Titles in non-Latin scripts such as Arabic or Chinese therefore produce an empty or partial slug; write those by hand.
5. Fix Caps Lock, Extra Spaces and Pasted PDF Text
Here is the accidentally typed in caps lock fix. If your paragraph reads “hELLO, tHANKS FOR YOUR EMAIL”, choose InVeRsE cAsE and every letter flips back. If it is all capitals, Sentence case gives you normal writing; then restore any names.
Shift F3 not working in Word? That Word shortcut cycles case, but many laptops need the Fn key held too. Otherwise, paste the text here, convert it and copy it back. If you are asking how to change case in Google Docs, it has a built-in capitalisation option under the Format menu; for sentence case or any code case, which it does not offer, use this page and paste the result back. The pasted passage arrives as plain text, so re-apply any bold or links.
On how to remove extra spaces from text: pick Remove extra spaces. It is the fix when text copied from PDF has extra spaces, doubled gaps, stray tabs or trailing spaces. It does not rejoin a sentence that the PDF broke across two lines, and it keeps blank lines, so paragraphs stay separate.
6. What It Does Not Do, and Where to Go Instead
A case converter changes letters. Neighbouring jobs belong elsewhere:
- Formatted documents. It reads .txt and .md and returns plain text, so it cannot change case inside a Word or PDF file while keeping the layout. To get text out of a PDF first, use the PDF to text converter; for scans and screenshots, the PDF OCR or image to text tool.
- Renaming files. To make file names lowercase or kebab-case, use the file renamer.
- URL encoding. The slug option makes a tidy path segment, not an encoded query value. For that, the URL encoder.
- Counting, patterns and comparing. For word and character totals, the word counter; to find or replace words by pattern, the regex tester (its replacements insert the text you type and cannot change capitals, so to recase one part of a passage, paste only that part here); to see exactly what changed, the diff checker.
It also does not keep acronyms intact, apply AP or Chicago rules, rename JSON keys (the JSON formatter only tidies JSON), show every case side by side, or make fancy Unicode fonts.
7. Why Use the Cortexis Case Converter
Here is what is different, stated so you can check every line.
Free, no account
No sign-up, no email and no daily limit. The tool at the top of the page is the whole product.
Writers and developers on one page
Title and Sentence case sit beside camelCase, snake_case and slugs: eighteen options in one row.
Rules you can predict
This guide lists the small words Title Case keeps lowercase and how code cases split words.
Your text stays private
What you paste is never stored on our servers and nothing is retained after you close the page.
Nothing is used for training
Your drafts, emails and code are never used to train anything.
Live, with copy and download
The result updates as you type, copies in one click and saves as a .txt file.
It is one of a wider set of free text and file tools offered on the same terms.
8. Frequently Asked Questions (FAQ)
How to change uppercase to lowercase without retyping?
Paste the text into the case converter above and choose lowercase, or Sentence case for normal capitals at the start of each sentence. Then press Copy and paste it back.
Which words does Title Case leave lowercase?
Short words such as a, an, the, and, but, or, of, on, to and per stay lowercase unless they start the text. It does not follow a named style guide such as AP or Chicago.
Why did NASA turn into Nasa?
Title Case, Sentence case and Capitalized Case give each word one capital and lowercase the rest, with no exceptions list for acronyms. Fix those words by hand afterwards.
How do I turn a column header into a snake_case name?
Paste the header and choose snake_case; spaces and punctuation become word breaks. Convert headers one at a time, because several lines are joined into a single name.
Can I convert a whole Word document or PDF and keep the formatting?
No. It reads pasted text or a .txt or .md file and returns plain text, so formatting is not kept. For a PDF, extract the text with the PDF to text converter first.
Does the slug option work for non-English titles?
Accented Latin letters lose their accents and are kept. Letters from other scripts, such as Arabic or Chinese, are dropped because the slug keeps only a to z, digits and hyphens.
Is my text stored or used for training?
No. What you paste is never stored on our servers, nothing is retained after you leave, and it is never used for training.
Can it count words or sort lines while converting?
Not in the same step. Use the word counter for word, character and sentence totals, and line tools for sorting, removing duplicates or numbering lines.
Working with data rather than prose? Reshape tables with the CSV to JSON converter, tidy queries with the SQL formatter, or turn notes into a web page with the Markdown converter. Curious about writing the code itself? Our free Python development course is a good next step.