A free beginner cybersecurity CTF: 100 in-browser challenges with server-verified flags and classroom leaderboards. A picoCTF alternative, no install.
Common questions
Is the CS++ Capture the Flag free?
Yes. All 100 challenges are 100% free to play. A free account lets you save your score across devices and join classroom competitions; only the optional AI GuardBot challenges require a membership or class seat.
Do I need to install anything, download a VM, or use the command line?
No. Everything runs in your web browser — no install, no virtual machine, no download, and no SSH. It works on locked-down school devices and Chromebooks, which makes it safe for classrooms.
Do I need to log in or sign up to play?
No login is required to start. Guests can play a free preview (one challenge per category) instantly, and progress is saved in your browser. Make a free account to unlock all 100 challenges, save your score across devices, and join class competitions.
Is it good for beginners and high-school students?
Yes. It is built as a true beginner ramp for ages 13-18 and AP / high-school computer science classes. Challenges start with simple encodings and include three free hints before optional point-cost hints, so absolute beginners can get their first flag without prior experience.
Can teachers assign this CTF to a class?
Yes. Teachers can assign the CTF as a classroom competition with a due-date countdown and a live class leaderboard, edit hints, and track progress per student — a classroom-friendly, no-install alternative to picoCTF that runs entirely in the browser.
What categories and skills does it cover?
Challenges span general-skills warm-ups, cryptography, web exploitation, forensics, steganography, reverse engineering and logic, programming, networking, OSINT, plus optional AI-security (prompt-injection) challenges — the core categories of a real jeopardy-style CTF.