Here are some popular pop-up free plugins that you can use for your WordPress website:
- OptinMonster
- Thrive Leads
- Icegram
- Hustle
- WP Notification Bar
- Hello Bar
- Popup Maker
- Pop up builder
These plugins can help you create various types of opt-in forms, lead generation forms, announcement bars, and other types of website pop-ups without the need for coding or paying for premium pop-up plugins.