Custom Chrome extensions and web scrapers that save to Sheets or a database

There are two separate jobs here. A Chrome extension changes or reads the page you are looking at, in your own browser. A scraper runs on a schedule on a server, fetches pages or data endpoints, and writes the results somewhere. I build either, and sometimes both together.

What a Chrome extension looks like in practice

Typical examples: a button added to a page that saves the current product or profile to a Sheet, a sidebar that shows extra data next to a page, or a tool that fills a repetitive form. Extensions today are built on Manifest V3. Per the Chrome developer docs, the background logic runs in a service worker that only runs when needed, and an extension may not load remotely hosted code, so all the JavaScript has to ship inside the package that the Chrome Web Store reviews.

In practice that means: no long-lived background page keeping state in memory (I store state in extension storage), permissions kept as narrow as possible, and updates delivered as new versions rather than code fetched from my server.

What a scraper looks like

A scraper is a scheduled job. It fetches a list of pages, reads fields such as title, price, stock or date, compares with the last run, and writes new or changed rows to Google Sheets or a database. Some sites need a real browser to render the page, some expose a JSON endpoint that is easier and more reliable.

I add:

• retry with sensible delays, so I do not hammer a site
• a record of every run and its row count
• an alert if a run returns zero rows or a field is suddenly empty
• de-duplication so reruns do not create double rows

Legal and terms caveats

• Read the site terms. Some forbid automated access. Check the robots.txt file, which states which paths the site asks crawlers to avoid. It is not a legal shield either way.
• Personal data brings privacy law into play, depending on where you and the people in the data are. Confirm with a qualified adviser.
• If the site offers an official API or data export, that is nearly always the better route.
• I will not build anything meant to bypass logins, paywalls or security measures.

Off the shelf versus custom

If you need one page scraped once, a no-code scraping tool or a browser export may be enough. Custom makes sense when the extraction logic is specific, the volume is steady, or you need clean output in your own system.

What I need from you

• The exact pages and the fields you want, with a few examples of the ideal output.
• How often it should run and where results should go.
• Confirmation that you are allowed to use the data this way.
• Access to the Sheet or database.

Sources

• Chrome for Developers, Manifest V3 overview: https://developer.chrome.com/docs/extensions/develop/migrate/what-is-mv3