Ticketed events can sell out, and then people email you asking whether a ticket will come back. This app gives them a proper place to wait.
Put the widget on your event page. While tickets are on sale it takes no room at all. The moment the event sells out, visitors see "Sold out. Join the waitlist", leave their name, email and how many tickets they need, and get their place in line straight away: "You are number 12 in line." Someone who signs up twice keeps their first place.
Everyone who joins shows up on the app's dashboard page in order, per event. When a refund or a cancelled order puts tickets back on sale, the page tells you. Click Email next to the first person and your mail app opens with a ready message and the link to the event, and the person is marked as emailed. First come, first served, and you stay in control of who gets the ticket.
The free plan covers any number of events, with up to 30 people per event and a small credit link under the widget. Premium removes the limit, gives each ticket type its own line (Standing and Seated, for example), adds a CSV download and one email to everyone waiting, and removes the credit link.