Lowercase converter
Drop everything to small letters. Handy for cleaning up text that arrived in capitals, and for normalising the values — emails, tags, slugs, keys — that are supposed to be case-insensitive but rarely are in practice.
Where lowercasing is the right fix
Email addresses are the classic case. The domain half is defined as case-insensitive, and although the local part technically is not, essentially every real mail provider treats it that way — so Support@Example.COM and support@example.com reach the same inbox. Storing both in a database as different users is a bug that shows up as "I already have an account but it says I don't".
Tags, slugs, hashtags and lookup keys have the same problem for the same reason. Normalising to lowercase on the way in is a two-character fix for a whole class of duplicate-record bugs.
Hostnames in URLs are case-insensitive and safe to lowercase. The path is not — /Docs and /docs are different resources to a strict server — so lowercase a URL only up to the end of the domain unless you know the server folds case.
Lowercasing is not always reversible
Case conversion loses information in a few languages, and it is worth knowing before you round-trip text through it. German STRASSE lowercases to strasse, but the word is normally written Straße — the sharp s uppercases to SS, and there is no way back. Greek final sigma changes shape depending on position, so uppercasing and lowercasing a Greek word can move the letter form.
Turkish is the well-known trap: the language has a dotted and a dotless i as separate letters, so lowercasing I should give ı in Turkish and i in English. Browsers use the locale-independent Unicode default, which means the English answer. If you are normalising Turkish user input for comparison, do it with a Turkish-aware collation, not with a plain lowercase.
Worked examples
Run through the same code the button runs, so the examples cannot drift from the tool.
| Input | lower case |
|---|---|
STOP SHOUTING AT ME | stop shouting at me |
Contact: Support@Example.COM | contact: support@example.com |
STRASSE | strasse |
Common questions
How do I convert text to lowercase?
Paste it into the box and click the lowercase button. Every letter is converted, including accented and non-Latin characters.
Should I lowercase email addresses before storing them?
In practice yes. Domains are case-insensitive by definition and virtually every mail provider treats the local part that way too, so normalising avoids creating two accounts for the same person.
Is lowercasing always reversible?
No. German ß uppercases to SS with no way back, and Turkish has dotted and dotless i as separate letters that a locale-independent conversion cannot distinguish.
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