You open a webpage, run your scraper, and get a CSV full of empty cells. The page looks fine in your browser. The data is clearly there. So what happened?

This is the most common scraping problem, and it has one root cause: JavaScript rendering .

How most scrapers read a page

When a basic scraper — including popular Chrome extensions like Instant Data Scraper — fetches a page, it reads the raw HTML returned by the server. That HTML is the skeleton of the page before any JavaScript has run.

The problem: most modern websites don't put their actual data in that initial HTML. They load it afterward, via JavaScript. The page your browser shows you is the result of HTML + JavaScript executing together. The initial HTML alone is often just a loading spinner and some empty containers.

So when a scraper reads the HTML directly, it gets those empty containers.…