Uppercase and Lowercase Converter
Switch the whole text to capitals or to lowercase in one step.
The simplest case conversion there is, and the one people need most often: take a block of text and make all of it uppercase, or all of it lowercase. No sentence detection, no exceptions, no cleverness that might surprise you.
It is more useful than it sounds because case matters in places where it is easy to get wrong. Identifiers, tags, product codes, CSS class names, and database keys are frequently required to be lowercase. Headings, labels on buttons, and legal notices are often required to be uppercase. Converting by hand invites typos in exactly the strings where a typo is expensive.
Conversion here is locale-aware rather than a naive byte swap. Accented characters convert in both directions without corruption, and the German sharp s expands to a double S when uppercased, which is what German orthography expects.
Examples
| What it handles | Input | Output |
|---|---|---|
| To uppercase, with ß | Straße café | STRASSE CAFÉ |
| To lowercase, with accents | HÉLLO Wörld | héllo wörld |
| Numbers and punctuation untouched | Order #42 — Ready! | ORDER #42 — READY! |
How it works
The text is passed through locale-aware case mapping, which knows that characters outside the basic Latin alphabet have their own uppercase and lowercase forms. That is why é converts to É rather than being left alone, and why ß becomes SS when uppercased instead of staying as a lone character. Line breaks, spacing, punctuation, numbers, and emoji are untouched — only letters change. Because the operation is a pure mapping, it is instant even for very large documents, and running it twice in the same direction produces the same result.
When people use it
- Making product codes or SKUs consistently uppercase.
- Lowercasing tags, slugs, or CSS class names before import.
- Converting a heading to capitals for a design that requires it.
- Normalizing a column of data where case was entered inconsistently.
Frequently asked questions
- Why does ß become SS?
- German has no single uppercase form of ß in standard orthography, so the correct uppercase rendering is SS. That is what locale-aware case mapping produces.
- Does it change my line breaks?
- No. Case conversion touches letters only. Line breaks, indentation, and spacing come back exactly as you pasted them.
- Is there a size limit?
- Nothing enforced. The conversion is a direct mapping and stays fast well past a megabyte of text.