Text diff
Paste two versions of the same page, an earlier and a later scrape or two API replies, and every line is marked as kept, removed or added, so a changed price or a new field stands out at once.
2 lines removed, 3 added, 2 kept
Trail running shoe- Price: $89.00+ Price: $79.00 In stock- Rating: 4.6 (212 reviews)+ Rating: 4.7 (230 reviews)+ Free delivery
Worked out in your browser. Nothing you paste is stored, sent or added to the page address, so tokens and cookies stay on your machine.
What it is for when you scrape
Monitoring is scraping the same pages again and comparing. A line diff is the plainest way to see what moved between two runs: a price, a stock line, a new delivery offer. It also catches the scraper's own failures, when a whole block disappears because a site changed its layout.
This site checks every vendor's pricing page the same way each day and records a price change only when the vendor's own page moved. For page-level monitoring at volume, extracting the fields you track to markdown or JSON first keeps the diff to the lines that matter.