Hi, welcome to the tutorial!

Right click the text below and click Inspect.
Right click this text.
Good.
Now right click this text and click Inspect.
Then double click it in Elements to edit it.
Change it to: 'edited_by_me'
When you are done, click:
Why this matters
You just changed the page by editing your browser’s copy of it.

In cybersecurity, this is important because a user can modify anything that lives in the client, like text, buttons, hidden fields, prices, or values stored in localStorage.

That is a client-side threat vector.
It means the system must not trust the browser for important decisions.

This site exists to show, in a safe way, how easy it is to tamper with client-side data and why real security must be enforced on the server.
Let's begin