🔬 Text Diff

Compare two texts with word-level highlights

▶ Open it on navigatorslab.com — free, no sign-up, nothing uploaded
navigatorslab.com/Text-Diff · 🔊 Watch Narrated Step-by-Step Tutorial Video · Watch Full Suite Hands-On Video
This repo's Pages site runs the actual tool: demo.html

Line diff with word-level highlights, similarity percentage, whitespace/case options, unified-diff export.

📖 Complete Step-by-Step User Guide

Step 1: Paste Original Text (Version A) Into the Left Pane (Original Text Editor (#textA))

• How to do it: Paste or type the baseline version of your contract clause, code snippet, or prose into #textA.
• Expected result: Original text is loaded in local browser memory.

Step 2: Paste Revised Text (Version B) Into the Right Pane (Revised Text Editor (#textB))

• How to do it: Paste the updated or redlined text into #textB.
• Expected result: Both versions are ready for Longest Common Subsequence (LCS) comparison.

Step 3: Click Compare Texts to Inspect Word-Level Highlights (Compare Button (#btnDiff) & Diff Output (#diffOut))

• How to do it: Click Compare (#btnDiff). Inspect #diffSummary (added/removed line counts and similarity percentage) and #diffOut, where intra-line word changes are highlighted in green (.w-add) and red (.w-del).
• Expected result: Subtle single-word edits (like 30 days → 45 days) stand out immediately.

Step 4: Export Standard Unified .diff Patch File (Download .diff Button (#btnDl))

• How to do it: Click Download .diff (#btnDl) to save a standard unified diff file with - and + hunks.
• Expected result: Standard .diff patch file downloaded locally.

🎛️ UI Controls, Shortcuts & Parameters Reference

Control / Shortcut	What It Does
Version A (#textA) & Version B (#textB)	Side-by-side text areas for original and revised text.
Compare (#btnDiff)	Runs the deterministic LCS diff algorithm with intra-line word highlighting.
Diff Summary (#diffSummary) & Output (#diffOut)	Shows similarity score, added/removed counts, and color-coded word diffs.
Download .diff (#btnDl)	Exports a standard unified .diff text file.

💡 Pro Tips & Real-World Workflows

• 💡 Use Text Diff before signing a counter-party's 'clean final PDF' of an NDA or MSA: copy the text from your draft into #textA and the text from their PDF into #textB to catch silent edits.
• 💡 AI agents can also call this exact diff engine deterministically via POST https://navigatorslab.com/tools/mcp (text_diff tool).
• 💡 You can pre-populate inputs via URL parameters (textdiff.html?a=...&b=...).

🧪 Concrete Example: Input → Engine → Output

Stage	What Happens	Details
1. Raw Input	Contract-v1.txt vs Counterparty-Redline-v2.txt	Counterparty claims 'minor typos fixed', but changed '30 days notice' to '90 business days notice'
2. On-Device Engine	Custom Longest-Common-Subsequence (LCS) line + intra-line word diff engine highlights exact token mutations	Runs 100% client-side in your browser tab under strict CSP (connect-src 'none').
3. Verified Output	Inline Word-Diff + Unified Patch (.diff)	91.4% similarity badge · '-30 +90 +business' highlighted inside line 14 · Exportable unified diff patch

@@ -14,1 +14,1 @@
-terminate with [-30-] {+90 business+} days written notice | Similarity: 91.4%

• 🔊 Narrated Step-by-Step Usage Tutorial Video (32s): demo.mp4 (also live at https://navigatorslab.com/tools/videos/textdiff.mp4)
• 🎬 Full Suite Hands-On Video Guide: https://navigatorslab.com/tools/videos/notebooklm-overview.mp4

✅ What it does

• Compare two texts with word-level highlighting inside changed lines
• Similarity percentage, whitespace/case options, unified-diff export
• Handles code, contracts and prose alike

🚀 Try it in 30 seconds

1. Paste both texts
2. Read word-level highlights and the similarity %
3. Export a unified diff

📸 Live UI in action

🔒 Private by design

• 100% on-device — files are processed in your browser and never uploaded to any server
• No accounts, no tracking, no cookies, nothing retained — open the page and work
• Works offline once loaded; fully mobile-friendly
• Free & open source (MIT) — use it at home, at work, anywhere

🤖 Built for humans and AI agents

• Deep-linkable via URL parameters — see the Agent Mode guide
• Machine-readable catalog: llms.txt · llms-full.txt
• MCP endpoint: POST https://navigatorslab.com/tools/mcp (tool catalog + deterministic text tools — see the main repo)
• No build step required to use any tool — just the URL

🛠 Under the hood

Custom LCS diff with word-level intra-line highlighting

Third-party components are catalogued in NOTICE; this repo is MIT-licensed (LICENSE).

🗂 The NavigatorsLab Tools suite

The full catalog — every tool in the hub with the same zero-upload promise, plus the lab's apps, CLIs and engines:

Tool	What it does
🛡 Photo Privacy Kit	Strip GPS, camera model and timestamps before posting	Open
🔐 Password Breach Checker	Has this password been breached? — it never leaves your tab	Open
🔍 Metadata & Hidden-Data Checker	See what's really inside a file — then strip it	Open
🗜 Image Shrinker	Hit “max 2 MB” portal limits without TinyPNG	Open
📄 Scan & Screenshot Cleaner	Phone photos of documents → clean, straight PDFs	Open
✍ Local E-Sign Pad	Sign this lease tonight — not DocuSign	Open
🧾 Receipts → One PDF	Shoebox of receipt photos → one date-sorted PDF	Open
🔢 Receipt OCR → CSV	Read totals off receipt photos, export for expenses	Open
🔳 QR Studio	Generate QR codes and decode QR images — no site sees them	Open
🎧 Audio Trimmer	Cut voice notes and clips on a waveform	Open
🧮 Invoice / Quote Generator	One-person shops: hours in, clean PDF out	Open
🗂 Batch Rename & Sort	IMG_5847.jpg → 2026-09-05-receipt-home-depot.jpg	Open
🖨 Print-Shop Prep	Exact sizes, bleed, DPI checks, print-ready PDF	Open
📑 PDF Pages	Reorder, rotate, delete and extract PDF pages	Open
🔬 Text Diff	Compare two texts with word-level highlights	Open
🎨 Reimagine	Redesign any HTML page from its own content	Open
📊 Text Stats	Words, reading time, readability, keyword density	Open
📜 PDF Studio	Edit the text inside your PDF — private, free, open source	Open
🩺 Design Health	18 deterministic design-quality checks for HTML — no LLM, no API key	Open
🔪 Skill Slice	Copy one Read-verified skill folder — a slice, not the pie	Open
🕵 liecatchers	Your agent said Done. Prove it — ten sensors, one RECEIPT.json	Open
📚 Book Guide MCP	Ship improvements with your books — agents cite, run playbooks, learn	Open
📡 Data Insights	Founder intelligence — daily & weekly tech signal briefs	Open
🪓 Iron Axe: Legacy	An original side-scrolling beat 'em up — Godot 4	Open

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One hub, twenty-four projects: https://navigatorslab.com/tools
Source & the whole suite: https://github.com/Kayforkind/NavigatorsLab-Tools