Privacy
Simple.Tools is built around browser-side workflows whenever that is practical. In plain terms, many tools process your input directly in the page instead of sending it to the server first. That is one of the reasons the site is designed as a collection of small focused tools rather than account-heavy apps. For common text, data, calculator, and formatting tasks, this usually means the work happens in your browser session.
At the same time, privacy should match the exact feature you are using. The site itself does collect and store some limited data for normal operation. The main server-side example is the comments system. When you submit a comment, the site stores the comment content, the name you entered, your selected rating, the tool slug, the language, and the time of submission. It also stores a hashed form of your IP address and a hashed form of your user agent string for rate limiting, duplicate detection, and abuse prevention. Comment-related security helpers such as CSRF protection and short-lived flash messages also rely on PHP session state.
Some features are intentionally stored only in your own browser. Favorites are a good example. The favorites list is stored client-side in IndexedDB, with a localStorage fallback if IndexedDB is not available. That means favorite items such as tool id, icon, name, short description, category, URL, and the local timestamp when the item was added stay in your browser rather than being written to the site database. Theme preference is also stored locally in localStorage. In a few cases, a specific tool may save temporary working state locally as part of the tool itself, such as a browser notepad style workflow.
There is also a small amount of temporary browser-side session handling. For example, the comment form uses sessionStorage to reduce accidental repeat submissions during the same browsing session. This is used to improve form behavior, not to build a cross-site profile of your activity.
If a tool clearly depends on a third-party script, a remote service, or a library loaded from outside the site, that changes the privacy surface of that page. In those cases, the practical behavior of the tool matters more than any generic statement. If you are working with highly sensitive content, the safest habit is still to review the exact tool behavior before using it.