Veil: Dark mode PDF viewer that preserves images

What it does

Veil is a PDF viewer that applies dark mode styling to documents while keeping images, charts, and diagrams intact. Instead of inverting everything including visuals, it inverts text and backgrounds while preserving image colors. The tool runs entirely in the browser, so files never leave the user's device. It includes OCR functionality that makes text trapped inside images selectable and searchable. Users can export dark-mode PDFs that work in any standard reader, and internal links, external references, and bookmarks remain functional.

Who it is for

The tool targets people who read PDFs at night or in low-light settings, particularly those working with scientific papers, textbooks, study materials, and documents heavy in charts or histology slides. Anyone who reads color-critical figures benefits from keeping those visuals unaltered while reducing eye strain from bright text on dark screens. The export feature appeals to users who want to share dark-mode PDFs across devices without vendor lock-in.

Pricing

The site does not show prices. The project is free and available with a donation option via Ko-fi, with a stated commitment to remain free forever.

How it stands out

Most dark mode PDF readers simply invert the entire document, destroying image quality and color information. Veil solves this by detecting images within the PDF structure and leaving them untouched while inverting only text and backgrounds. The built-in OCR layer extracts text from images, making previously non-selectable content in charts, labels, and captions available for copying. Running fully client-side means no server processing, no file uploads, and offline functionality after installation. Export preserves the dark styling in a standard PDF format that opens correctly in any reader, avoiding platform lock-in.

What a founder should check

A competitor should verify the technical moat: how difficult is it to replicate the image detection within PDF.js operator lists and the OCR integration? PDF rendering is a crowded space, but the specific combination of dark mode plus image preservation is narrower. Second, assess switching costs by examining whether users who export dark PDFs can easily move to competitors or are locked into Veil for ongoing reading. Third, evaluate pricing pressure: the project is donation-based and open source, so a commercial alternative would need significant added value to justify paid tiers when users can self-host the free version.

Thinking of building something like this?

Every launch here is a competitor to somebody's idea. If yours is close, check it against the market before you build: the Full Check names the rivals, the prices and the gaps.