Self-hosted alternatives to arena

A

arena

Spawn N parallel candidates at the same task, pick a base

arena is an agent skill from Cursor's plugins collection that runs several candidate solutions to the same task in parallel, picks a base, and grafts the strongest parts of the other candidates into it. Its phases are: frame the task, fan out to parallel candidates, cross-judge them, pick a base, graft, and verify. In the framing phase every candidate receives the same prompt, so the prompt acts as the contract. The agent states the artefact each candidate should produce and writes a rubric of three to six concrete, gradeable criteria for success. The rubric is kept for the judging stage, because candidates only see the task. The skill selects the models to run from a configured list in the user's rules, with defaults and family matching when a configured model is refused, and it omits the model setting when the entry means the parent model. The approach is useful for tasks where there are several reasonable designs and you want the evidence to decide between them, rather than trusting the first attempt. It costs more than a single run, so it suits decisions that matter. It is listed on skills.sh, where the page shows install counts and GitHub stars for the Cursor plugins repository, and its security audits all pass. Install it with npx skills add https://github.com/cursor/plugins --skill arena.