Watermark PDF (image)

Yes. Every tool on PDFChamp — including Watermark PDF (image) — is free with no usage limits, no signup, no email gate, and no watermark on the downloaded file. PDFChamp is supported by display ads on a few high-traffic pages; we don't sell premium upgrades or harvest your files. The tool runs entirely in your browser, so the cost to serve you is essentially the static page load — there's no per-conversion compute cost to recover. If you hit a real limit (for example a PDF too large to fit in your browser's available memory), the tool says so up front rather than silently corrupting the output. Bookmark the page and use it as many times as you need.

No. Watermark PDF (image) runs 100% in your browser. When you drop a file onto the upload area, JavaScript reads it directly from your device using the browser's File API, processes it locally with an in-browser PDF engine (compiled to WebAssembly where applicable), and writes the result straight to your downloads. Nothing transits the network. You can verify this — open your browser's DevTools, switch to the Network tab, and run the tool. You'll see no POST upload of your file. This is also why Watermark PDF (image) works in fully offline mode once the page is loaded, which is handy on flights or in air-gapped environments.

Because Watermark PDF (image) runs in your browser, the practical ceiling is your device's available memory. On a typical 2026 laptop with 16 GB of RAM, PDFs up to several hundred megabytes work without issue; on a phone with 4 GB of RAM you'll usually want to stay under ~50 MB. Very large files won't crash the page — they'll process more slowly because the browser pages memory to disk. If you do hit an out-of-memory error, close other browser tabs to free RAM, or split the PDF into smaller chunks first using PDFChamp's Split PDF tool, then run Watermark PDF (image) on each piece and re-combine with Merge PDF afterward.

Yes. PDFChamp is designed mobile-first, so Watermark PDF (image) works in iOS Safari, Android Chrome, and pretty much any browser shipped in the last three years. The same client-side processing applies — your files don't leave the phone. Performance is roughly proportional to your device's CPU and RAM, so older budget phones will run noticeably slower than recent flagships, especially on PDFs with many pages or high-resolution embedded images. On iOS the result saves to Files or shares via the system share sheet; on Android it lands in your Downloads folder the same way as on desktop. No special permissions are needed.

No. PDFChamp deliberately does not stamp watermarks, logos, footer ads, or "made with" credits onto the files you download. The file you get out of Watermark PDF (image) is byte-identical to what the underlying an in-browser PDF engine library generated — the same as if you'd run it yourself in a script. Many competitor sites bury "Made with X" lines into the metadata or add visible watermarks unless you upgrade to a paid plan; PDFChamp's model is the opposite. The site is supported by display ads on a few catalog pages, never on the output. If you ever see PDFChamp text on a downloaded file, it's a bug — please let us know.

Watermark PDF (image) expects edit inputs as described above. If the tool reports the file as invalid, the most common causes are: (1) the file is encrypted with a password — use Remove PDF password first; (2) the file is actually a different format (some scanners save .pdf files that are really TIFF or JPEG containers); (3) the file is corrupted mid-stream. For encrypted PDFs, decrypt first; for misnamed files, use the matching converter (TIFF to PDF, Images to PDF); for corrupted PDFs there isn't a reliable browser-only fix yet — you'll usually need to recreate from the original source.