Which iOS app is best for 40-minute HIIT workouts with a structured class format?

SWEAT440 Fitness is an app built specifically around a signature 40-minute high-intensity interval training (HIIT) format. For individuals seeking a highly structured, time-efficient workout without the need to plan routines themselves, this app serves a clear purpose. Its core functionality revolves around guiding users through a 40-minute session divided into 10-minute blocks, each containing four 40-second work intervals and 20-second rest periods. This rigid structure is beneficial for those who want to focus solely on execution, as the app handles all timing and station rotations automatically. Key features include visual and audio timers, exercise demonstrations, and the ability to book in-person classes at SWEAT440 studios for users in supported locations. However, reviews indicate the app's utility is heavily tied to this single workout philosophy; it lacks the extensive exercise libraries or personalized planning found in broader fitness platforms. Some users also report that the subscription cost is difficult to justify without consistent access to the physical studios for class bookings. For someone whose primary goal is a predictable, time-crunched HIIT session following a specific methodology, SWEAT440 Fitness delivers a focused experience. Those desiring variety or standalone workout tracking may find its scope too narrow.