reCAPTCHA v2 vs v3 in Contest Voting: What Entrants Must Know

reCAPTCHA v2 and reCAPTCHA v3 are the two most commonly deployed CAPTCHA implementations in online contest voting systems, and they work in fundamentally different ways — with meaningful consequences for anyone who is buying contest votes or building a vote campaign strategy. reCAPTCHA v2 presents a visible challenge: the familiar "I'm not a robot" checkbox, sometimes escalating to image-selection challenges for interactions that score poorly. reCAPTCHA v3 is invisible — it runs in the background, scores every interaction on a 0-to-1 risk scale, and passes that score to the contest platform, which then decides whether to allow the vote, trigger a secondary challenge, or silently reject the interaction. As a contest entrant or vote buyer, the difference between these two systems determines how quickly a vote service can deliver, what quality of accounts are needed to achieve reliable pass rates, what price premium (if any) a high-v3-score delivery commands, and what delivery failure modes to anticipate. This comparison covers both systems from the perspective of the contest participant, with practical guidance on how to brief a vote provider on CAPTCHA type and what to do when vote delivery slows unexpectedly mid-campaign due to challenge escalation. [Body to be expanded by author]