Saving Eyes, One Slide at a Time
Project: Dark PDF
Repo: wakeupguruu/dark-pdf
Tech Stack: TypeScript, React, PDF.js, Vercel
The Problem: Late Night Eye Strain
The inspiration for this tool came from a very specific, painful reality: exam season. I found myself pulling all-nighters, staring at hundreds of pages of bright white PDF slides in a dark room. The contrast was blinding, and my eyes were burning.
I tried existing solutions—browser extensions and "dark mode" converters—but the results were disappointing. Most tools either:
- Simply inverted the colors, turning images into negatives (making diagrams look like crime scenes).
- Ruined the text formatting entirely.
- Required sign-ups or uploaded my private study notes to a server.
I didn't want a complex editor; I just wanted to read comfortably without going blind.
The Solution: A Privacy-First Dark Mode Engine
I built Dark PDF to do one thing perfectly: convert documents into a clean, elegant dark mode while preserving the integrity of the content.
Unlike basic color inverters, I focused on a smart conversion logic. The tool targets the background and text specifically—turning the canvas pure black and the text high-contrast white—while attempting to keep images and diagrams natural.
Key Features:
- Smart Inversion: Backgrounds go dark, text goes white, but images remain intelligible.
- Privacy First: Zero server uploads. The conversion logic runs entirely in the browser (client-side), so your documents never leave your machine.
- No Friction: No sign-ups, no watermarks, and no installation required. Just drag, drop, and read.
Technical Approach
The project is built with TypeScript for type safety and deployed on Vercel for speed.
The core challenge was manipulating the PDF rendering layer. Instead of treating the PDF as a flat image, the tool interacts with the PDF structure to modify the rendering palette before re-assembling it. This ensures that the text remains crisp rather than becoming a blurry, inverted screenshot.
The Outcome
What started as a personal utility to survive exam week has turned into a deployed web app that anyone can use. I’ve tested it on a wide range of academic papers, slides, and ebooks to ensure the formatting holds up.
It is simple, fast, and does exactly what it says on the tin: gives your eyes the rest they deserve.
Try it out at darkpdf.vercel.app