https://evelynytliu.github.io/prooflens/index.html

ProofLens – Catch Errors before ink hits paper

Hi, I'm Evelyn.

For years, my proofreading workflow was simple but painful: open two PDFs, manually drag the windows until they overlapped perfectly, and hold my breath to check for errors. It worked, but it was incredibly slow.

I designed ProofLens to take over the tedious parts of my job as a Packaging Specialist. It automatically aligns and scales your files, so you can skip the setup and get straight to the checking.

It’s the tool I wish I had 18 years ago. Now, I’m hoping it can also help you save time.

🚀 What is ProofLens?

ProofLens is a standalone Windows desktop app that compares two files (Reference vs. Proof) and helps you spot visual differences instantly.

It’s not a bloated enterprise suite. It’s a focused, lightweight tool designed to solve one specific problem: Visual Quality Control.

✨ Key Features

• ⚡ The "Flash" (Auto-Strobe): Hold [Space] to flash between the two images. Your eyes will instantly catch even a 1px shift or a missing comma because it "vibrates" on screen.
• 📂 Broad File Support: Supports PDF, AI (Adobe Illustrator), EPS, JPG, and PNG. You can compare a vector AI source file against a rasterized JPG proof from a vendor.
• 🎯 Smart Red Boxes: The app automatically scans and draws Red Boxes around differences.
• ✂️ Ignores Crop Marks: Vendor sent a file with bleed and color bars? No problem. The Auto-Align engine snaps the content together so you can compare the actual design, not the paper size.
• 🔒 100% Offline & Safe: ProofLens processes everything in your RAM. No cloud uploads. No AI training on your work. Your NDA files never leave your computer.
• 📚 Batch Power: Drag in a list of files. The app handles multi-page PDFs and batch lists smoothly.

⚠️ "Real Talk" (Important Notes)

I want you to be happy with this tool, so let’s manage expectations. I am a solo developer building this for real-world use:

1. It compares Pixels, not Code: ProofLens looks at the visual output (like a digital light table). It does not do OCR, spell-checking, or extract text. If it looks different, it marks it.
2. Resolution Matters: To compare PDFs or AI files, the app converts them into high-resolution images. While optimized for 300 DPI, extremely large or complex vector files might take a moment to load.
3. PDF Rendering: ProofLens uses the same fast rendering engine as Google Chrome (PDFium). While effective for most files, complex print-ready PDFs (e.g., with heavy CMYK layers, Spot Colors, or transparent shadows) may show slight visual differences compared to Adobe Acrobat. Think of this as a content checker, not a color proofer.
4. Human Judgment Required: Automated detection (Red Boxes) can sometimes have false positives (due to anti-aliasing) or miss extremely faint changes. Always use the "Strobe Mode" (Spacebar) for your final human check.
5. Windows Only: This version is strictly for Windows 10 / 11.
6. Liability: This tool is an assistant to aid your workflow, not a replacement for your professional approval. ProofLens cannot be held responsible for printing costs or errors that are missed. You are the final gatekeeper.

💎 Pricing (No Subscriptions!)

• Standard License ($15): The price of a few coffees. You get the full tool, lifetime updates for v1.x, and my gratitude.
• Team License ($49): If you need to install it on multiple machines for your team (up to 5 users). Includes priority support.

🛡️ The "No-Regrets" Guarantee: If ProofLens doesn't save you time or catch a mistake in the first 30 days, just reply to your receipt email. I’ll refund you. No hard feelings.

💻 System Requirements: Windows 10 / 11 (64-bit) No installation required (Portable .exe)

🇹🇼 Made with code & coffee in Taiwan. Designed by Evelyn YT Liu.