This is really really amazing. Good job!

Some feedback from someone who is also working on a subscription service based on cloud computing magic:

- Realistically, charging $20 - $40 a month means you'll need a lot of customers to signup to make anything significant in revenue.

- Acquiring new customers might be difficult for this type of service because direct sales would be too costly to make a profit. You would definitely need to run ads to gain a large customer base.

- If you run ads you'd have to position it as an up-time monitoring service since the volume around searches for automated headless browser testing solutions isn't going to be high. The cost of acquisition through marketing will be pricey especially since you offer a free plan that offers what most people would need.

- The Chrome extension is super cool and very impressive, but I think the average small business owner might be intimidated by all the javascripty things you throw at them on the landing page. A good tagline might be along the lines of "Know when something breaks on your site"

- You will spend a lot of time answering support emails.

- I can see this service really taking off if you find a way to bundle it with an eCommerce shopping cart. Maybe create a Magento plugin or Shopify app?