Local Diff – Offline Compare Tool for Prompts, Images & Workflows

Local Diff – compare prompts, images, PDFs, spreadsheets and folders, 100% offline

Spot exactly what changed between two prompts, two generations, two workflows or two training datasets. Local Diff is a free comparison tool that runs entirely in your browser from one HTML file. There's nothing to install, no account to create, and nothing is uploaded anywhere.

What it does

Local Diff puts two versions of something side by side and highlights every difference. It works like the popular online diff checkers, except your files never leave your computer. That matters when you're comparing unreleased models, client work or private datasets.

It's built for the everyday "what did I change?" moments in AI art:

• Prompts and parameters: paste two generation infos and see the exact words, weights, seeds and settings that differ.

• Generations and edits: compare an original against an inpainted, upscaled or retouched version. You can swipe between them, fade between them, or see a pixel-difference map, and zoom right in.

• ComfyUI workflows and configs: compare two .json workflows or training configs line by line.

• Training datasets: compare two LoRA dataset folders to see which images were added, removed or changed. You can then open any caption file to see the edited tags.

• Training logs and spreadsheets: compare two CSV or Excel files cell by cell.

• Model cards and licences: compare two PDF or Word documents.

Features

Five comparison modes, each in its own tab.

Text (prompts, JSON workflows, configs, code, any text file)

• Split or unified view, with changed words or single characters highlighted inside each line

• Ignore whitespace and ignore case options, plus folding of unchanged lines

• "Next change" button, and export to a standard .diff patch file

• Open or drag in files, or just paste
  

Images (PNG, JPG, WebP, GIF, SVG, BMP, AVIF)

• Four views: side by side, swipe slider, fade, and a pixel-difference map with an adjustable tolerance

• Zoom up to 3200% in every view, with both sides locked together; pixels show as sharp squares above 300%

• Zoom and pan with buttons, Ctrl or ⌘ + scroll, pinch, double-click or the keyboard (+ − 0 1)

• Images of different sizes can be scaled to match, for example an original against its 2× upscale. They can also be aligned top-left or centred.

• Shows the percentage of pixels changed, and saves the difference map as a PNG
  

Documents (PDF, Word .docx, OpenDocument .odt, RTF, HTML, text)

• Text comparison of the document contents, including tables

• Visual page-by-page comparison for PDFs, with all the image tools above
  

Spreadsheets (Excel .xlsx and .xlsm, OpenDocument .ods, CSV, TSV)

• Side-by-side grids that scroll together, with changed cells highlighted

• Added and removed rows detected, and every sheet compared, with a colour dot showing which sheets changed

• "Changed rows only" filter, and export of the change list as a CSV
  

Folders

• Drop or choose two folders to list every file as modified, added, removed or identical

• Click a file to open its detailed comparison, using the right mode for its type

• Skips .git, node_modules, .DS_Store and similar by default, and the list is editable
  

Everywhere

• Light and dark themes, a layout that works on phones and tablets, and remembered settings

• Works fully offline: everything, including the PDF reader, is built into the one file

Setup guide

Setup takes under a minute and needs no installation. Any recent Chrome, Edge, Firefox or Safari (2023 or newer) on Windows, macOS or Linux will run it.

1. Download Local-Diff-v1.0.zip with the Download button on this page.

2. Extract the zip. On Windows, right-click it and choose Extract All. On a Mac, double-click it.

3. Double-click Local-Diff.html. It opens in your default web browser. If it opens in another app, right-click it and choose Open with, then pick your browser.

4. Optional: bookmark the page, or move the file anywhere you like, such as your desktop or a USB stick. It's completely self-contained.

Quick start

• Text: paste the old version on the left and the new version on the right, then click Find difference, or press Ctrl or ⌘ + Enter.

• Images, Documents, Spreadsheets: drop a file on Original and one on Changed. The comparison appears straight away.

• Folders: drop or choose two folders, then click any file in the list to see what changed inside it.

• Zooming images: use the + and − buttons, Ctrl or ⌘ + scroll, pinch or double-click. Drag to move around. Press 0 to fit and 1 for actual pixels.

• Updating: download the new version and replace the old file.

FAQ, privacy and credits

Is anything uploaded? No. Every comparison runs inside your browser on your own computer. The file makes no network requests, so it works with Wi-Fi switched off.

Why is the file about 2.7 MB? The PDF reader and the Office file reader are built in, so nothing needs downloading when you use it.

What can't it do?

• Old Office formats (.doc and .xls) aren't supported. Save them as .docx or .xlsx first.

• Scanned PDFs contain pictures of text rather than text. Use the PDF Visual comparison for those.

• Dragging folders onto the page works best in Chrome and Edge. Other browsers can use the folder picker instead.

Is it safe? It's a plain web page. Open it in a text editor any time to see exactly what it contains.

Credits and licence. Local Diff © 2026 PixelBlitterBoy. All rights reserved. It includes two open-source libraries, used under their licences: pdf.js by the Mozilla Foundation (Apache License 2.0) and JSZip by Stuart Knightley and contributors (MIT License). Full notices are under Credits & licences at the bottom of the app, and in the zip.

Feedback and bug reports are welcome in the comments. If it saves you time, a like or a review helps others find it. 🕹️🤓👌