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FlagForge is an open-source Capture The Flag (CTF) platform built to make hosting and participating in cybersecurity challenges accessible to everyone. This page gives you an overview of what FlagForge is, who it’s designed for, and what you can do with it.

What is FlagForge?

FlagForge is a full-stack web application that lets you host, manage, and participate in CTF competitions. Whether you’re a student sharpening your skills, an organizer running an event, or a club setting up a private competition, FlagForge provides everything you need in a single deployable platform. Players browse challenges organized by category — Web, Crypto, Forensics, Pwn, and more — submit flags in the flag{...} format, and track their progress on a real-time leaderboard. Admins create and manage challenges, assign badges, and control who has access to admin features. FlagForge is licensed under the GPL-3.0 license and is free to self-host.

Technology stack

FlagForge is built with the following technologies:
TechnologyRole
Next.jsFull-stack React framework for pages and API routes
TypeScriptType-safe language used throughout the codebase
MongoDBDocument database for users, challenges, and scores
NextAuth.jsAuthentication via Google OAuth with JWT sessions
Tailwind CSSUtility-first CSS for the UI

Key features

Challenges

Browse and solve challenges across multiple categories. Each challenge includes a description, optional file attachments, and configurable hints.

Flag submission

Submit flags in the flag{...} format. The platform validates your answer instantly and updates your score.

Dynamic flags

Each user receives a unique flag variant, preventing flag sharing and ensuring fair scoring across all participants.

Real-time leaderboard

Track scores and rankings live as participants solve challenges throughout the competition.

Badges

Earn badges for solving challenges, reaching milestones, and demonstrating skills. Admins can create and assign custom badges.

Admin dashboard

Create and manage challenges, control user roles, and assign badges from a dedicated admin interface.

Next steps

Ready to start using FlagForge? Follow the quickstart guide to create your account, browse challenges, and submit your first flag.

Quickstart

Create your account and submit your first flag in minutes.

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