# CaptchaArena

The work builds CaptchaArena, a large-scale fine-grained computer-use training dataset of 20,000 interactive CAPTCHA puzzles across 20 types and five interaction modes, where every solution is replayed in a real browser and accepted by the page's own verifier, together with 20,000 screenshot-action trajectories (18,000 carrying judge-filtered step-by-step reasoning annotations) and pixel-mask supervision for irregular targets; training a single 9B policy, CaptchaAgent, on it reaches 70.5 average Pass@1 after supervised fine-tuning and 71.7 after reinforcement learning with the environment verifier as reward, versus 11.4 for the untrained backbone, 35.2 for the strongest open-weight GUI agent, 69.2 for the strongest closed-source model, and 94.1 for humans.

The work builds CaptchaArena, a large-scale fine-grained computer-use training dataset of 20,000 interactive CAPTCHA puzzles across 20 types and five interaction modes, where every solution is replayed in a real browser and accepted by the page's own verifier, together with 20,000 screenshot-action trajectories (18,000 carrying judge-filtered step-by-step reasoning annotations) and pixel-mask supervision for irregular targets; training a single 9B policy, CaptchaAgent, on it reaches 70.5 average Pass@1 after supervised fine-tuning and 71.7 after reinforcement learning with the environment verifier as reward, versus 11.4 for the untrained backbone, 35.2 for the strongest open-weight GUI agent, 69.2 for the strongest closed-source model, and 94.1 for humans.