A privacy-friendly anti-spam system for registering accounts on a public Matrix Synapse homeserver. Before an account is created, the client solves an Argon2id puzzle, slow and memory-hungry on purpose (~30 minutes by default), which makes it expensive for bots to do at scale.

Synapse's own open registration gets turned off; Vigil is the only
thing that can create an account, and it only does that once a
client proves it solved a fresh puzzle.

Features

• Privacy-friendly
• A lot harder to bypass than traditional anti-spam systems
• Optional CLI tool to solve cryptographic challenges for people who don't wanna use JavaScript
• Small codebase