Frequently asked questions

Yes. Every tool on AntiUpload is free. There is no signup, no credit card, no premium tier, no file-count limit, and no watermark on output. The site is supported by small banner ads on tool pages — adblockers do not affect functionality.

No. Every conversion runs entirely in your browser using WebAssembly and standard browser APIs. There is no upload step, no staging server, and no temporary cache on our infrastructure. You can verify in your browser's Network tab — every conversion shows zero outbound bytes for your file.

The same way Google Docs draws your cursor without sending each keystroke to a server: modern browsers can run real code locally. AntiUpload ships compiled libraries (pdf.js, pdf-lib, mozjpeg, oxipng, libheif, tesseract.js) as WebAssembly modules. When you drop a file in, the browser runs those libraries on your device against your file, then offers the result for download — never crossing the network.

For privacy: yes — your file never leaves your device, so we cannot see, store, or leak it. For correctness: every conversion is best-effort. We are honest about each tool's limits on the About page. If you are converting a legally significant document, always verify the output by opening it before sharing.

AntiUpload caps individual files at 100 MB per tool, with the actual limit set by your device's memory. Phones can typically handle PDFs up to 30-50 MB; desktops handle 100 MB without issue. Larger files are not technically blocked but may cause the tab to slow down or crash. For very large PDFs, try Compress PDF first to bring the file under 100 MB.

Yes. Every tool works in mobile Safari, Chrome, and Firefox. Drag-and-drop, file picker, HEIC photo handling, and download all behave the same as on desktop. Heavy operations (large PDF compression, OCR) take longer on phones but they finish.

After your first visit, the static assets are cached. Most tools work fully offline once their WebAssembly modules have loaded. The few that fetch font data or pdf.js worker chunks at runtime will need a connection the first time you use them.

Those services upload your file to a server, process it there, and send the result back. That works, but you have to trust them with the document. AntiUpload runs in your browser, so the trust question never comes up — your file never goes anywhere. Trade-off: AntiUpload uses your device's CPU and memory, which means very large or unusual PDFs can be slower on AntiUpload than on a server-side competitor. For most files this is not noticeable.

Running AntiUpload costs us almost nothing because the heavy work happens on your device, not ours. Our infrastructure is a static site on Cloudflare's edge — orders of magnitude cheaper than a server-side PDF service. Banner ads cover the bandwidth bill. There is no subscription tier we are upselling and no data we are reselling.

Honest list: scanned PDFs in non-Latin scripts (OCR is English-default), complex magazine layouts with irregular columns, PDFs with form fields or math equations in unusual fonts, and PDFs that use the JBIG2 or JPEG2000 image formats. Password-protected encrypted PDFs are also held back pending native AES-256 implementation. We document the live tools' real limits on each tool's page. See About for the full picture.