Hacker101 offers a free web security class with lessons and Capture the Flag challenges.
CTFtime
vsCTF Sites
CTFtime vs CTF Sites
How do CTFtime and CTF Sites compare? Here are the facts side by side: pricing, platforms, open-source status and what each one is for.
| Directory detail | CTFtime | CTF Sites |
|---|---|---|
| What it is | CTFtime lists upcoming and past Capture the Flag events, teams, tasks, ratings, and writeups. | CTF Sites lists Capture the Flag sites and provides a directory for finding cybersecurity challenges. |
| Website | ||
| Type | Website | Website |
| Topic | ||
| Pricing | Not confirmed | Not confirmed |
| Platforms | Web | Linux, Web |
| Open source | Not stated | Not stated |
| Language | English | — |
| Alternatives |
Other options to consider
Sites similar to both CTFtime and CTF Sites.
The CTF101 wiki introduces Capture the Flag competitions and explains related security concepts.