There is information people type into convenient web tools without thinking. What to be careful about.
Web tools come in two kinds: those that compute inside your browser, and those that send what you enter to a server and return a result. With the first, your input never leaves your device; with the second, it reaches that server. For identical functionality, this difference decides almost all of the safety question.
The most reliable check is to load the page, disconnect from the internet, and try the feature. If it still works, it runs in your browser. You can also watch the network tab in developer tools to see whether a request fires as you type.
As a rule, never type a password you actually use into any online tool โ including strength checkers. The same goes for internal company documents, national ID numbers, bank account numbers and medical records. If you must test something, use fake values with the same shape as the real ones.
Free tools still cost money to run. Advertising or paid tiers are the usual answers. When there is no visible business model and the tool asks for sensitive input, it is worth considering that the input itself may be the product.
Tools that convert images or documents often upload the file to a server. Photos can carry the location and time they were taken as metadata, and documents can carry author information. Deciding whether to strip that first, or to use a tool that processes in the browser, is the safer path.
Each button runs this keyword on that search engine