Every "free online tool" site has the same shape: pick a task — resize an image, merge a PDF, decode a JWT — upload a file, wait, download the result. That upload almost never needs to happen. Browsers have had the APIs to do this work locally for years.
Source: [Dev.to](https://dev.to/amritanshu_gaurav_8c70b9e/why-i-built-a-browser-only-tool-platform-and-what-broke-that-rule-16df)