PDF Redline Comparator

DrawDiff

See exactly what changed. Pixel by pixel.

Pixel-accurate overlay comparison for engineering drawings, technical documents, and contracts. Color-coded redlines show every addition, deletion, and unchanged element at a glance.

▶ Launch DrawDiff How it works ↓
DRAWDIFF — REDLINE OVERLAY PREVIEW
Original
Revised
Overlay
Original only (removed)
Revised only (added)
Unchanged (both)
🔒
100% Local Processing
Your files never leave your device
🚫
No Uploads
No server receives your documents
🔑
No Account Required
Open and use — nothing to sign up for
🛡️
Sensitive Document Friendly
Safe for sensitive and controlled documents
How It Works

Three steps to a redline.

No installation. No account. Open DrawDiff in any modern browser and you're ready.

01
📄
Load Your PDFs
Drag and drop your original and revised PDFs into the tool. Multi-page documents are fully supported — all pages compared in order.
02
⚙️
Run Compare
Hit Run Compare. DrawDiff renders each page at high resolution and performs a pixel-by-pixel comparison. Progress updates in real time.
03
🔍
Review & Export
Pan and zoom the color-coded overlay. Inspect specific regions, export individual pages as JPGs, or package everything into a single PDF redline.
Color Code

Read a redline in seconds.

Green — Original Only
Content present in the original PDF that has been removed or moved in the revision.
Red — Revised Only
New content added in the revised PDF that wasn't in the original.
Cyan — Unchanged
Content present in both PDFs within the diff threshold — nothing changed here.
Dark — Background
Empty space. Background color is adjustable — dark, white, or original document background.
Features

Built for real drawing review.

Every feature exists because engineering drawing comparison has specific problems that generic tools don't solve.

🎯
Pixel-Accurate Overlay
Every pixel compared at configurable render scale. Catch even the smallest line weight change or dimension edit.
📑
Multi-Page Support
Compare entire drawing sets. All pages processed in one run — page 1 vs 1, page 2 vs 2, across hundreds of sheets.
⊕
Alignment Tool
When a view shifts between revisions, the standard compare becomes noise. Crop a region, pick a reference point on each, and compare aligned.
🔎
Region Inspector
Ctrl+drag any area to pop up a three-panel view — overlay, original, and revised side by side. Copy to clipboard or save as JPG.
Ⓣ
Text Compare
When shifted text makes the pixel overlay unreadable, box-select any text region to extract and diff the actual words — additions in green, removals in red. Works on native PDF text; OCR support coming soon.
⬇
Flexible Export
Export all pages as individual JPGs with a custom filename prefix, or package the entire comparison into a single PDF. Copy region comparisons directly to clipboard.
Use Cases

Who uses DrawDiff.

Anyone who needs to understand exactly what changed between two versions of a document.

🏗️
Engineering Drawing Review
Compare MIL-spec drawings, CAD exports, and technical revisions. Catch dimension changes, added notes, and modified tolerances.
🏛️
Architecture & Construction
Review plan revisions and change orders. Identify what moved, what was added, and what was removed between drawing sets.
⚖️
Legal & Contracts
Redline contract amendments and regulatory filings. See every word-level change without manually reading every page.
🛡️
Defense & Government
No files leave your machine — suitable for sensitive and proprietary documents.
Get Started

Ready to see
what changed?

Free to use. No signup. Works in any modern browser. Your documents stay on your machine.

▶ Launch DrawDiff Free