Frequently asked questions

No. There's no server component to this site's core tools \u2014 files are read with your browser's File API, processed in memory using JavaScript libraries, and the result is offered back to you as a download. Nothing is transmitted anywhere.

After your first visit, PDF Ultra Pro can be installed as a lightweight app and used offline for previously cached tools, thanks to its service worker and web app manifest.

Because nothing leaves your device, sensitive documents never cross a network in the first place. That said, always keep your own device and browser up to date, since that's the boundary that matters here.

100MB per file, and up to 40 files in a batch for tools that support multiple files. These limits exist to keep your browser responsive, since processing uses your device's own memory.

Current versions of Chrome, Firefox, Edge and Safari, on both desktop and mobile.

Compress PDF works by re-rendering each page as a compressed image, which is what makes it effective on scanned or image-heavy PDFs. That process rasterizes any text, so it's not the right tool if you need to keep selectable, searchable text \u2014 in that case, try reducing embedded image size manually instead.

Real PDF password protection and removal require robust encryption support that isn't reliably available in the open-source libraries this site uses client-side. We'd rather mark it "Coming soon" than ship something that doesn't actually protect your file.

Faithfully converting office formats to PDF typically requires a full layout engine (like the one inside Word or LibreOffice). That's not something we can do accurately and safely without a server, so it's on our roadmap rather than in the current tool set.