Hacker101 offers a free web security class with lessons and Capture the Flag challenges.
CTF Sites
CTF Sites lists Capture the Flag sites and provides a directory for finding cybersecurity challenges.
About CTF Sites
CTF Sites is a directory of Capture the Flag (CTF) sites, which are online information security competitions where users solve challenges to find hidden text called a flag. The site groups listed sites into three sections: best known CTF sites, beginner CTF sites, and a longer general list. Each entry has a short description of the site's focus and a link to start.
The homepage states that the directory includes only permanent CTFs. It does not host challenges itself, so access to each challenge depends on the external site. The homepage also invites visitors to suggest or submit sites through a Discord server and notes that the project accepts donations.
Key features
- Lists CTF sites in best-known, beginner, and full collection sections
- Short description of each listed site's focus area
- Beginner section with starter sites such as picoCTF and OverTheWire
- Sites covering binary exploitation, web exploitation, and reverse engineering
- Cryptography and Linux command-line challenge sites included in the list
- Submission of new CTF sites through a linuxpwndiary Discord server
Best for: People new to Capture the Flag challenges who want a curated list of permanent sites to start learning cybersecurity skills.
Good for
- Groups sites into best-known, beginner, and full list sections
- Each listed site includes a brief description of its focus
- Covers several topics, including web, binary, cryptography, and reverse engineering
Watch out for
- Descriptions are brief, one line per site
- Includes only permanent CTFs, so temporary competitions are not listed
- Challenges run on external sites, not on CTF Sites itself
CTF Sites at a glance
- Website
- ctfsites.github.io
- Category
- Education & Learning › Learn to Code
- Type
- Website
- Pricing
- Not confirmed. Check the site
- Platforms
- Linux, Web
- Open source
- Not stated
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
CTF Sites alternatives
Tools and sites you could use instead, ranked by how closely they match.
CTFtime lists upcoming and past Capture the Flag events, teams, tasks, ratings, and writeups.
The CTF101 wiki introduces Capture the Flag competitions and explains related security concepts.
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CTF Sites FAQ
What does CTF mean?
CTF stands for Capture The Flag. It is an information security competition in which participants solve challenges, ranging from decoding a string to hacking into a server, to find a specific piece of text called a flag.
Does the directory list temporary CTF competitions?
No. The homepage states that CTF Sites contains only permanent CTFs.
How can a CTF site be added to the directory?
The homepage says site owners or anyone who knows of a CTF site can join the linuxpwndiary Discord server to suggest it.
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