RafflePress is the best WordPress-based contest and giveaway plugin. It helps you create a viral feedback loop by incentivising your visitors to share your giveaways on Facebook, X (formerly Twitter), Instagram, and other social media platforms. RafflePress also integrates with most of the popular email marketing platforms.

Grow your email list, followers, and website traffic with viral giveaways and contests in WordPress.

If you prefer a SAAS-based solution, my recommendations are in the Social Sharing & List Building section further up this page.