TonniTools is built to run locally in your browser. Since no data ever leaves your device, everything works, even without internet.
Paste or type text and convert it between seven formats in real time: sentence case, Title Case, UPPERCASE, lowercase, aLtErNaTiNg case, URL-friendly slugs, and trimmed whitespace. The slugify option handles special European characters correctly — ä becomes ae, ø becomes oe, å becomes aa, and so on — making it ideal for generating clean URL slugs from Danish, German, French, or other European-language text. See the converted output live as you type. Copy the result to your clipboard or download it as a .txt file.