The short version
Scissor Text never receives your text. When you open a tool, your browser downloads the website. What you type, paste or open from a file stays in the memory of your tab; the tool works on it there, on your own processor, and the result is yours to copy or download. Closing the tab erases everything.
What runs where
Every tool, from the word counter to the JSON formatter, is a small piece of JavaScript that runs in your tab. Text to speech uses the voices built into your browser and operating system.
The server only hosts the site's files. It has no endpoint that accepts text, so there is nothing that could receive yours. A small customer care service on the same domain receives only what you choose to send, such as feedback, plus anonymous page counts.
Verify it yourself
Open your browser's developer tools, switch to the Network tab and use any tool. You will see the page's own files load, small anonymous page-count requests to /_care/, and no request carrying your text. You can also disconnect from the internet after the page has loaded: every tool keeps working.
The site also sends a strict Content Security Policy that tells your browser to block the page from contacting any other server, so even a mistake in our code could not send your text elsewhere.
Works offline
After your first visit, a service worker stores the site in your browser's cache, so the tools open and work with no connection.