You will practise on a few small apps we built just for this site. They are not real products or real companies. They are sandboxes for you to test, and they run inside your browser with no setup.
Each one is a normal working web app. Buttons respond, forms reject bad input, data loads a moment after the page appears. That last part matters, because a page that loads instantly teaches you nothing about timing, and timing is where most real test failures come from.
Here are the three.
Nimbus, a sign-in page
Nimbus is a login page. An email field, a password field, and a sign-in button.
It behaves like a real one. The correct details take you to a dashboard. A wrong password shows an error. An empty form shows validation messages, meaning the small warnings that appear when a required field is blank.
This is where you will write your first test, because signing in is the shortest complete journey an app has.
Terra Supply, an online store
Terra Supply is a small shop. It has a product list, a cart, and a checkout form.
You can add items to the cart, change quantities, remove things, and pay with a card number. The cart count in the corner updates as you go, and the checkout form rejects invalid cards.
Shops are useful for practice because so much can go wrong in a way that still looks fine. A cart badge can show the wrong number. A subtotal can ignore quantity. You will write tests that catch exactly those.
PipelineHQ, a contact manager
PipelineHQ is a CRM, meaning a tool for keeping track of customers and deals. It has a table of contacts, a search box, filters, and forms for adding and editing.
Tables and search are where beginners write their weakest tests, so this app exists to give you practice with both.
Why these and not a real website
You could point a test at any public website. Two problems with that.
The site can change without warning, so your test breaks for reasons that have nothing to do with what you wrote. And you cannot break the site on purpose to check whether your test would notice.
Here we can do both. When you solve a practice problem, we run your test against the working app, then break that exact behaviour and run it again. If your test still passes, it was not really testing anything, and we tell you which behaviour it missed.
That check is the reason these apps exist. A test that cannot fail is not a test, and the only way to know the difference is to try.
Where to start
Start with Nimbus. It is the smallest, and the next lectures use it for their examples.
You do not need to memorise these names. Whenever one comes up in a later lecture, you will get a short reminder of what it is.
Remember this: these are practice apps, built to behave like real ones and safe to break.
Next: installing Playwright on a real project.