CTFd Alternatives in 2026: An Honest Comparison

CTFd is the default CTF platform for good reason. It's open source, well documented, has a plugin ecosystem, and thousands of events have run on it. If you're looking for an alternative, it's usually because of one specific problem, not because CTFd is bad.

This post compares four options on the things that matter during a live event. One of them is our product, Zero Day Arena, so read that section with the appropriate skepticism. We've tried to be fair to the others. Feature sets change: check each project's current documentation before deciding.

The short version

CTFd

What it's good at. Maturity. CTFd has the largest community, the most tutorials and the most third-party plugins. If you need a feature, someone has probably written a plugin for it. The admin interface is complete: challenges, users, teams, scoreboards, notifications, all in the browser. The paid hosted version removes the operations burden for organizers who don't want to self-host.

Where organizers struggle. Out of the box, flags are static: every team submits the same string, so flag sharing can only be found by comparing submissions after the fact. Self-hosted scoreboards under heavy concurrent load need careful caching and tuning, and there are public issues discussing scoreboard performance at scale. Per-team containers and per-team flags are possible, but through plugins you'll need to evaluate, install and maintain.

Choose it if you want the broadest ecosystem, need to self-host, and have someone comfortable running and tuning a Python web application during the event.

rCTF

What it's good at. rCTF was built by the redpwn team for their own large public CTF, with performance as a primary goal. It's lean, fast and handles large Jeopardy events well. If your event is a big open competition and you want a lightweight, high-throughput Jeopardy platform, it's a strong choice.

Where organizers struggle. It's intentionally minimal. There's no Attack-Defense, no built-in per-team containers, and fewer admin conveniences than CTFd. The community is smaller, so you'll be reading source code more often than documentation.

Choose it if you're running a large, public Jeopardy CTF with an experienced team, and raw scoreboard performance matters more than admin features.

GZCTF

What it's good at. GZCTF has strong built-in support for container challenges: per-team dynamic instances on Docker or Kubernetes, with dynamic flags injected per team. Because those flags are unique, it can flag cross-team submissions on dynamic challenges. For a Jeopardy event that leans heavily on containerized challenges, it covers a lot without plugins.

Where organizers struggle. You need to run and operate the container backend yourself, which is the hardest part of any CTF's infrastructure. Per-team flags apply to dynamic container challenges, so static challenges still share one flag. There's no Attack-Defense mode.

Choose it if you're self-hosting a Jeopardy event with many container challenges and have someone comfortable operating Docker or Kubernetes under load.

Zero Day Arena

This is our platform. Here's what it does differently, and what it doesn't do.

What it's good at.

• Both formats. Jeopardy and Attack-Defense on one platform. For A/D we run the full game plane: a WireGuard VPN per team, sandboxed checkers, HMAC flags per team, per service and per tick, and SLA-weighted scoring.
• Anti-cheat by default. Every challenge gets per-team flags, not only container challenges. Cross-team submissions are flagged in real time with an evidence bundle, and penalties need two organizers to confirm.
• Hosted. There's nothing to deploy. The scoreboard has been load-tested at 500+ teams with updates under 5 seconds at p95, and we publish those numbers.

What it doesn't do.

• No self-hosting. If your event must run on your own infrastructure, for policy or air-gap reasons, this isn't the right choice.
• No plugin system. You get the platform's feature set. That's deliberate, since it's what lets us guarantee behavior under load, but it means less flexibility than CTFd.
• Not free. Plans start at ₹4,999 per event. Open-source platforms cost you hours; we cost money. For a small club event with a volunteer who enjoys running servers, CTFd or rCTF may be the better trade.
• Limited A/D capacity. We run one large Attack-Defense event at a time, so A/D dates book out.

How to decide

Ask what you're actually trying to fix:

• "We want the most flexible, community-supported option." → CTFd.
• "We're running a huge public Jeopardy event and need it fast." → rCTF.
• "Our event is mostly container challenges and we can run Kubernetes." → GZCTF.
• "We want Attack-Defense, real anti-cheat, or simply no servers to run." → Zero Day Arena.

If you're unsure, book a 30-minute demo. If one of the open-source options fits your event better, we'll tell you.