Going
Going, formerly Scott's Cheap Flights, is a subscription service that emails members cheap flight deals from their chosen airports.
Hopper
Hopper is a mobile-first app that predicts future flight prices and notifies users when to book for the best deals.
Mighty Travels
Mighty Travels is a subscription service that provides airfare deal alerts, mistake fares, and mileage optimization opportunities.
Priceline
An OTA for flights, stays, cars, and packages known for Express Deals. Great for flexible travelers who want to save with opaque discounts and bundle options.
SecretFlying
SecretFlying is a free platform highlighting error fares, flash sales, and unusually cheap flights worldwide.