What NilPDF needs from your browser, and where it has limits.
| Browser | Minimum version |
|---|---|
| Chrome / Chromium-based (Edge, Brave, Opera) | Recent versions (last ~2 years) |
| Firefox | Recent versions (last ~2 years) |
| Safari (macOS / iOS) | Recent versions (last ~2 years) |
NilPDF relies on SharedArrayBuffer, WebAssembly, and Web Workers, all of which require a reasonably modern browser. Very old browser versions are not supported and will show an error rather than a broken tool.
NilPDF works on mobile Chrome and Safari, but large files may process more slowly or use more memory relative to available device RAM than on desktop. Very large PDFs (100+ MB) are more likely to hit memory limits on mobile devices.
NilPDF's PDF engine runs as WebAssembly via Pyodide, which requires SharedArrayBuffer support. This in turn requires the page to be served with Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp headers, which NilPDF's hosting is configured to send. If you're running a local mirror of the site without these headers, tools will fail to load the engine.
Because processing happens in your browser's memory rather than on a server, very large PDFs (typically 100 MB and up, depending on your device) can exhaust available memory. If this happens, the browser tab may slow down, become unresponsive, or crash. Closing other tabs, using a device with more RAM, or splitting a large file into smaller pieces first can help.
After your first visit, NilPDF's app shell and PDF engine are cached by a service worker, so most tools continue to work without an internet connection on a subsequent visit — though this has not been exhaustively tested across every tool and browser combination, so treat it as best-effort rather than a guarantee.
Most tools support password-protected PDFs — enter the password in the field provided before or after selecting the file, depending on the tool. The password is used only in-browser to decrypt the file locally.
NilPDF's "PDF to Text" tool extracts embedded text only. It does not perform OCR (optical character recognition), so scanned documents that are essentially images of text will not yield extracted text. OCR is not currently available in NilPDF.
The Repair PDF tool attempts best-effort recovery of readable pages from truncated or structurally damaged PDFs. Severely corrupted files, or files damaged in ways outside common failure patterns, may not be recoverable.