How saving works
The notepad uses the Web Storage API, the localStorage object that every current browser provides. All notes are kept together as one JSON list under a single key belonging to this site. Each entry holds an identifier, the title, the text and the time of the last edit. When you change anything, the page waits 400 milliseconds for you to stop typing and then rewrites the whole list.
On your next visit the page reads that list back and shows your notes again. Nothing in this path touches a server, which you can confirm in the browser's network panel: typing produces no requests. Saving also keeps working if your connection drops while the page is open, since it needs only the browser.
What deletes your notes
Local storage belongs to one browser profile on one device, tied to this site's address. Clearing browsing data with the cookies and site data option ticked wipes it, as does a Clear site data button in the site settings or a cleanup utility that resets browsers. Clearing only the history or the cache leaves notes alone. Uninstalling the browser or deleting its profile removes them too.
Private and incognito windows get a temporary store that is discarded when the window closes, so a note written there does not survive. Safari may also remove a site's stored data when you have not opened the site for about a week. And storage is finite, usually around 5 MB per site: a lot of plain text, but when a write fails the pill changes to Can't save in this browser.
Working with more than one note
The Notes list shows each note's title and the date and time of its last edit, most recent first. Click a row to open it. The bin icon appears when you hover over a row or reach it with the Tab key, and asks before deleting. Titles are free text and also name the download, with spaces and punctuation turned into underscores, so Meeting notes becomes Meeting_notes.txt.
Keep the notepad open in one tab at a time. Each tab loads the notes when it opens and writes the full list back when you type, so two tabs do not see each other's changes and the last one to save wins. If you have edited in two tabs, copy the text out of one before typing in the other.
Backing up and moving notes
Download .txt saves the open note as a plain text file, one note per click. There is no export-all button and no import. To bring a note back, open the file in any editor, copy the contents and paste them into a new note. For anything you would be upset to lose, download it the day you write it.
Nothing syncs between devices or browsers. Chrome and Firefox on the same computer hold separate stores, and your phone holds another. To move text across, send yourself the downloaded file, or paste a short note into the QR code generator as Text and scan it with the phone. The count under the editor covers words and characters. The word counter adds sentences, paragraphs and reading time.
What not to keep in it
Local storage is not encrypted by the page. Anyone who can use your browser profile can open this page and read the notes, and browser extensions with access to the site can read them too. On a shared or public computer, treat the notepad as a scratch pad: download what you need and delete the notes before you leave. Passwords, recovery codes and card numbers belong in a password manager.
The editor is plain text. It has no bold or headings, no images, no search across notes and no version history. An overwritten paragraph is gone once the pill reads Saved on this device, apart from what the browser's undo still holds in the open tab. It suits drafts, snippets, command lines and to-do lists better than documents you need to format or share.