Flagprint

Every team gets its own flag and its own files.
A shared flag tells you who leaked it.

An open-source plugin that stops flag sharing in CTFd. Per-team flags, per-team challenge files, and shared-flag detection that names the leaker. Free, for the CTFd you already run.

A team pastes another team's flag, sees Incorrect, and the admin is told who copied whose flag

What it does

Unique flags per team. Write flag{st3g0_l0v3s_y0u_{team}}; each team's code is an HMAC of the challenge and the team. No flag table.
Per-team files of any kind. Swap a sample flag inside text, binaries, pcaps and zips, or let your generate.py build each team's file in an offline sandbox.
Who leaked it. A copied flag is a plain "Incorrect" for the player and a live alert for you, with both teams, the player, IP and time.
Admin tools. Share alerts, flag lookup, shared IPs, per-team flag regeneration, an optional Hall of Shame.
Invisible to players. The challenge type looks like a normal one; nothing hints that flags differ.

Install

cd CTFd/CTFd/plugins
git clone https://github.com/rj-karan/ctfd-flagprint flagprint

Restart CTFd and open Admin → Flagprint. Script delivery also pulls the sandbox image: docker pull ghcr.io/rj-karan/flagprint-generator:latest.