Show HN: MetaArena – Compare & Rank 5,353 Meta Global AI Hackathon Projects

The author built MetaArena, a site that presents two projects from Meta's Global Developer Hackathon head-to-head and lets users pick the stronger one, ranking them on a leaderboard using the Bradley-Terry algorithm used by LLMArena and DesignArena. The hackathon had a $1M prize pool, 34K applicants, 20K accepted developers, and over 5K submitted projects, which made human review infeasible and AI rubric scoring disappointing.