Black out sensitive personal data, financial numbers, and confidential notes in PDFs with true rasterized redaction, then sign with a handwritten or uploaded signature. 100% in your browser — zero bytes uploaded.
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PDF documents up to 100MB · 100% processed locally on your device
Geek check: open DevTools → Network tab — 0 bytes of your data uploaded.
A notorious mistake in document security is drawing a black rectangle over sensitive text in a standard PDF editor or presentation software. While visually covered, the underlying characters remain fully embedded in the PDF's text stream. Anyone can press Ctrl+A and Ctrl+C or search with Ctrl+F to copy the “hidden” Social Security Numbers, addresses, or confidential prices.
Our tool solves this through Thorough Mode: any page that contains redaction boxes is rendered at 2x high resolution and converted into a flattened raster image with the black boxes painted directly over the pixels. The original vector text streams, hidden metadata, and font glyphs are completely eliminated.
Many online PDF signers require you to upload confidential contracts, employee agreements, or financial records to their remote cloud servers. With YuliusBox, your document never leaves your device. You can draw your signature naturally with a mouse, trackpad, or touch stylus, or upload a scanned signature image. The signature is rendered directly into the PDF stream at crisp native resolution.
Thorough Mode (enabled by default) rasterizes any page containing redactions into a flattened high-resolution image with the blackout rectangles baked into the raw pixel data, discarding the original text streams and vector objects entirely. In contrast, visual cover mode merely draws black boxes on top of the existing PDF page; the underlying text characters remain intact in the document stream and can still be searched, selected, or copied by anyone opening the file.
Signatures created here are simple electronic signatures (SES) — graphical stamps of your handwritten signature or uploaded image. Under laws such as the US ESIGN Act and EU eIDAS regulation, simple electronic signatures are generally valid for everyday commercial agreements, purchase orders, approval forms, and NDAs. However, they do not provide cryptographic certificate-based non-repudiation (such as Advanced or Qualified Electronic Signatures). Legal enforceability depends on your jurisdiction, governing law, and document requirements.
No, never. All document parsing, rendering, redaction, signature stamping, and final PDF generation take place entirely within your browser using WebAssembly and client-side JavaScript (pdf-lib and PDF.js). Zero bytes of your document or signature leave your machine.
Standard PDFs store textual information as coordinates and font character codes in a content stream. When a page is rasterized, the PDF rendering engine flattens all fonts, vectors, and layers into a single grid of pixels (bitmap), and the black redaction rectangles paint over those exact pixels. Because the original PDF content stream is replaced with the flattened image, the text data is physically destroyed and cannot be retrieved.
Pages without any redaction marks are copied directly from the original PDF as lossless vector pages. Their crisp fonts, selectable text, internal links, and compact file size are preserved 100% intact. Only pages containing redactions undergo rasterization when Thorough Mode is active.