IT and software
The playground runs total(numbers) in a sandboxed frame. The SQL tasks use a fixed employees table. Neither tool deploys code or reads this site's cookies.
8 min
Coding MCQ
Functions, SQL, git, and Big-O, in plain language.
10 min
JavaScript playground
Write total(numbers) in the browser. The preview cannot read this site's cookies.
10 min
SQL practice
Three SELECTs against a four-row employees table.
12 min
Tech interview practice
Four questions scored on clarity and a named result.