Frequently Asked Questions

Correct. Every tool on DSPDF runs entirely inside your web browser. Your file is read with the browser's FileReader API and processed locally by JavaScript libraries. Nothing is transmitted over the network. You can verify this yourself: open DevTools (F12), go to the Network tab, clear requests, then use a tool. You'll see no outgoing request carrying your file. Or disconnect from the internet entirely and use any tool — it still works.

No file content, ever. The only thing stored on your device is your theme preference (dark/light), kept in local storage. If the site owner enables analytics or ads, additional cookies may be set — see the Cookie Policy.

No. There is no sign-up, login, email, or verification. Open a tool and use it.

Yes, all tools are free. There's no catch — no "premium tier", no export watermark, no waiting queue. If the site owner enables advertising, ads help cover hosting costs, but they never interfere with the tools.

Analytics is off by default. If the site owner enables it, it collects anonymous page-view statistics. It never sees your files, filenames, or any user-identifying information.

There's no fixed limit — the practical ceiling depends on your device's RAM, since all processing is local. Most modern laptops handle 100 MB PDFs comfortably. Older phones may struggle above 30-40 MB. If a tool fails on a large file, try a device with more memory, or split the PDF first.

Yes. DSPDF is built mobile-first and works on modern Android and iOS browsers. Large files process more slowly on phones because mobile CPUs are slower and memory is more constrained. All features work; performance varies.

Yes. Once a tool page has loaded, you can disconnect from the internet and everything still works. This is the strongest proof that processing is local. (Note: the first visit needs internet to load the page and any libraries from CDN.)

For PDF tools: PDF files. For JPG to PDF: JPG, PNG, and WebP. For signature upload: PNG or JPG. For HTML to PDF: HTML or plain text.

Not directly — browsers don't decode HEIC natively. Convert HEIC to JPG on your phone first (iPhone: Settings → Camera → Formats → "Most Compatible").

No — and no browser-based tool can, reliably. Editing existing PDF text requires reconstructing the layout, which current open-source libraries can't do. Our PDF Editor lets you add new content on top of your PDF: text, images, shapes, signatures, and annotations.

Split produces multiple output files. Extract produces one output file containing selected pages. Both are useful — pick based on how many files you want at the end.

Yes. Our compression converts each page to an image, then rebuilds the PDF. This reduces file size significantly but makes text non-selectable. If you need searchable text afterwards, use OCR to rebuild a text layer, or accept that the text is now an image.

Yes — use the Metadata Editor to view and edit title, author, subject, keywords, creator, and producer. Clearing metadata before sharing is a good privacy habit.

No. Watermarks are drawn into the PDF's page content and can't be removed from the output file. Always keep your original.

Depends on your input. Clean, printed, 300 DPI scans work well (~95%+ character accuracy in English). Handwriting, low-resolution scans, and complex multi-column layouts produce poor results. See the OCR article for detailed accuracy figures.

Yes. Enhance PDF offers automatic cleanup, grayscale, black and white, color boost, contrast, brightness, sharpening, an adjustable eraser and edge cropping. The preview updates as you work.

Yes. Page Numbers lets you choose the format, position, font, size, margin and page range. The preview updates when settings change, and you can manually refresh it when needed.

Yes. Annotate PDF supports movable sticky notes, text stamps, image stamps and freehand drawing. Image-stamp controls appear only when the Stamp tool is selected.

No. The eraser paints a white raster area; it is not a secure redaction method. For sensitive content, use the dedicated Redact PDF workflow and follow its secure-output guidance.

No. Our Unlock PDF tool removes protection from files where you already know the password. It does not brute-force or crack unknown passwords, and never will.

It depends on whether the underlying library exposes encryption in the browser build. Our tool checks at runtime. If encryption isn't available, it tells you honestly and offers a rasterization fallback rather than faking a "protected" file. See the Protect PDF page for the details.

Depends on jurisdiction and receiving party. Our signature tool produces visual signatures — an image on the page — not cryptographic digital signatures. For legally critical documents (contracts, affidavits, government forms), use a dedicated eSignature service with identity verification and audit trail, or check with a lawyer about requirements in your jurisdiction.

Only if you use the rasterize option. Drawing black boxes over content without rasterizing does NOT remove the underlying text — it's still extractable. Our Redact PDF tool offers both modes and warns clearly which is safe.

No, and we couldn't if we wanted to — we never receive it in the first place. See the Privacy Policy.

Modern browsers: Chrome, Edge, Firefox, Safari, and their mobile counterparts. Older browsers (Internet Explorer) are not supported. If something doesn't work, try updating your browser.

Because it's happening on your CPU. Server-based tools can parallelise across many machines; browsers use one device. Large files, high DPI settings, and OCR are the slowest operations. Patience is real — our progress bars reflect actual work, not animation.

Because your CPU is doing genuine work. Compression rasterizes every page; OCR runs neural networks on each word. This uses real compute and generates real heat. It's normal, especially on phones.