Inverse Case Converter
Use the CaseSwitch Inverse Case Converter to swap every uppercase letter to lowercase and every lowercase letter to uppercase. It is the quickest fix for Caps Lock plus Shift mistakes (tHIS iS wHAT hAPPENED). Paste, copy, done — processing stays in this browser.
Written by the CaseSwitch editorial team. We maintain these tools in the browser so drafts, keys, and images stay on your device.
Last reviewed: 23 July 2026
Processed locally in your browser. Nothing is sent to a server.
Paste or type text to convert. Output stays empty until there is input.
Character count: 0 · Word count: 0 · Line count: 0
Examples
Simple swap
Input
Hello World
Output
hELLO wORLD
Classic Caps Lock plus Shift mistake
Input
tHIS iS wHAT hAPPENED
Output
This Is What Happened
CamelCase identifier (usually do not invert code)
Input
XMLHttpRequest
Output
xmlhTTPrEQUEST
Brand-style mixed case
Input
iPhone
Output
IpHONE
Digits stay; only letters flip
Input
ABC123xyz
Output
abc123XYZ
How to use
- Paste the inverted or Caps Lock–mangled text into the input panel.
- Confirm names and brands look right. If you still need normal prose, run Sentence Case next.
- Copy the repaired result.
What this tool is for
Inverse case (also called swap case) flips the case of each letter while leaving digits and symbols alone. It is the fastest repair when Caps Lock was on and you also held Shift on the first letter of each word, producing the classic inverted mess. It is also useful for reversing a novelty string or building a test fixture that must look case-scrambled. It is not a substitute for sentence case or title case when you want normal prose.
How it works
Each character is inspected. If it has an uppercase form different from itself, it becomes lowercase; if it has a lowercase form different from itself, it becomes uppercase. Digits, spaces, and punctuation pass through unchanged. “Hello World” becomes “hELLO wORLD.” Camel-style identifiers reverse awkwardly: “XMLHttpRequest” becomes “xmlhTTPrEQUEST,” and “iPhone” becomes “IpHONE.” Running the converter twice restores the original string.
When to use it
Rescuing a paragraph typed with Caps Lock and Shift, reversing alternating-case jokes, checking how a UI looks with inverted labels in a fixture, and fixing a short paste before you apply sentence case for readable prose.
When not to use it
Do not invert finished title case hoping to get sentence case — you will scramble the heading. Do not invert source code, JSON keys, or API paths you still need to run. Do not invert a whole document that is already correct; use lower case or sentence case when everything is truly ALL CAPS with no shifted exceptions.
How it compares to related tools
Lower case flattens everything. Sentence case rebuilds sentence capitals from punctuation after a lowercase pass. Alternating case imposes a new rhythm instead of flipping what you already typed. Inverse case preserves which letters were emphasized — just swapped — which is why it repairs Caps Lock plus Shift better than a blanket lowercase. Walkthrough: How to fix Caps Lock text.
Common mistakes
Running inverse case twice by accident (which restores the original and looks like “nothing happened”). Inverting JSON keys or camelCase identifiers. Expecting numbers to change. Inverting mixed-language text without previewing characters that have no case pair.
Caps Lock repair workflow
If every letter is truly uppercase with no Shift exceptions, Lower case or Sentence case is enough. If the first letter of each word is wrong because Caps Lock and Shift fought each other, inverse case restores the intended mixed casing in one pass. After that, apply sentence case for a paragraph or title case for a heading, then restore brands (iPhone, McDonald’s) by hand.
Idempotence, Unicode, and empty input
Inverse case is its own inverse: apply it twice and you get the original. Characters without a case pair (digits, most emoji, many symbols) are unchanged. Mapping uses the same simple Unicode upper/lower rules as the rest of this suite — it does not apply Turkish dotted-I special cases. Empty input produces empty output.
Frequently asked questions
I typed with Caps Lock. Is inverse case or sentence case better?+
If the first letters of words were shifted, inverse case restores the intended mixed case. Then use sentence case if you want normal prose. If everything is truly A–Z with no shifted exceptions, lower case or sentence case is enough.
Does inverse case change numbers?+
No. Only letters that have a case pair are swapped. Digits and symbols pass through.
What happens if I run it twice?+
You get the original text back. Inverse case is its own inverse.
Will it fix “XMLHttpRequest” into a usable identifier?+
No. Inverting camelCase produces nonsense like “xmlhTTPrEQUEST.” Do not run this tool on code you still need to compile.
Is my text uploaded?+
No. Conversion runs in this browser. Nothing is sent to a server.
Does CaseSwitch upload this text?+
No. Conversion, cleaning, and counting for this page run in your browser. Drafts are not sent to CaseSwitch for processing.
Related guides
Read our original articles on this topic.
Tips
How to Fix Accidental Caps Lock Text
Typed with Caps Lock on? Paste into a case converter — sentence case for prose, lowercase for slugs. No retyping required.
Guides
What Is Alternating Case? Mocking Text, Examples, and When to Skip It
Alternating case (hElLo) is the mocking-text pattern, not a Caps Lock fix. See exactly how letters are counted, how it differs from inverse case, and when it reads as an insult.
Related tools
Alternating Case Converter
Convert text to aLtErNaTiNg cAsE.
Upper Case Converter
Convert text to UPPERCASE.
Lower Case Converter
Convert text to lowercase.
Sentence Case Converter
Capitalize the first letter of each sentence automatically.
Title Case Converter
Apply title capitalization rules to headings and names.
Capitalized Case Converter
Capitalize the first letter of every word.