Terms of Service Change Highlighter

WHAT IT DOES

Terms of Service Change Highlighter automatically tracks and visualizes changes to legal and policy documents on the web. It saves a snapshot of any page you visit, then compares future visits to that snapshot, highlighting exactly what's been added, removed, or modified. The script uses a line-by-line diff algorithm that works at paragraph, sentence, or word-chunk sensitivity to detect even small changes. Added sections appear in green, removed sections in red with strikethrough, and modified sections in yellow. A panel overlay shows a summary of changes with counts for each type, so you can quickly assess the significance of updates. This is ideal for monitoring terms of service, privacy policies, user agreements, terms of use, and any other legal documents that companies frequently update without notice. Perfect for privacy advocates, legal professionals, compliance officers, and anyone who wants to stay informed about changes to the agreements that affect their data and rights.

WHERE IT RUNS

This script runs on any webpage—the same URL will be compared across visits. It operates entirely within your browser tab, reading the page's text content and storing snapshots locally using GM_setValue. The script cannot access other tabs, your browsing history, bookmarks, downloads, or any data outside the current page. All settings—including highlight colors, auto-save preference, diff sensitivity, and summary-only mode—are stored locally and never transmitted anywhere.

HOW TO USE

After installing with the BotGentz extension, navigate to the Terms of Service or policy page you want to monitor. Click "Save Snapshot" to store the current page content. On your next visit to the same page, click "Compare with Snapshot" to see what's changed. The script highlights additions, removals, and modifications directly on the page, and the panel shows a summary with counts of each change type. Use the diff sensitivity dropdown to adjust how fine-grained the comparison is—paragraph for broad changes, sentence for more detail, or word for the most granular comparison. Customize highlight colors for added, removed, and modified sections. Enable auto-save to automatically store snapshots on each visit, building a change history. Click "Copy Change Report" to export a summary of changes to your clipboard.

THE REAL MECHANISM

The script extracts page content using a TreeWalker that traverses text nodes in the document body, filtering out script and style tags. The content is split into sections based on the user's sensitivity setting: paragraphs (using p, div, section, article, and li elements), sentences (using regex to split by sentence boundaries), or word chunks (groups of 10 words). The diff algorithm compares the new content array against the stored snapshot array. It builds frequency maps of lines to identify added and removed sections, then finds modified sections by comparing lines that share significant word overlap (more than 3 common words but less than 80% identical). This approach handles common use cases like reworded clauses, added paragraphs, and removed sections. When changes are detected, the script applies visual highlighting by wrapping matched text in span elements with background colors—no innerHTML is used for untrusted data. Snapshots are stored per page URL, with a maximum of 10 snapshots per page to manage storage size.

THE PANEL

The TOS Change Highlighter panel is a BGPanel component that you can drag anywhere on your screen by its header. It snaps to the nearest edge when released, keeping your workspace organized. The panel collapses to a small bubble showing only the emoji icon when minimised—click to expand it again. You can resize the panel horizontally to see more of the settings. Press the Escape key to collapse the panel instantly. Your panel position and size are saved per-site.

PLEASE NOTE

This script requires the free BotGentz browser extension to function. The diff algorithm works on text content only and does not compare formatting, images, or interactive elements. Legal documents often have dynamic content (e.g., date stamps, cookie consent banners) that may change on every visit—consider this when reviewing results. The script uses a simplified diff approach and may not detect all changes in heavily formatted or dynamically generated pages. Snapshots are stored locally in your browser storage and may be lost if you clear browser data. The script never reads or writes password fields, hidden inputs, or file inputs. It stores only page content snapshots, highlight color preferences, diff sensitivity, auto-save preference, and summary-only mode locally. No document content, policy data, or personal information is ever collected, transmitted, or shared.