What is the best alternative to Daily Cardio Workout - HIIT on iPhone?

HIIT | Down Dog, S tier, #1 in hiit workouts.

Is there a free alternative to Daily Cardio Workout - HIIT?

Yes: HIIT | Down Dog (S tier, #1) is free to download, with in-app purchases.

Yes. 2 apps rank above it in hiit workouts: HIIT | Down Dog (#1), 7 Minute Workout (#2).

Daily Cardio Workout - HIIT is A tier, #3 of 7 in hiit workouts. Here is everything that competes with it on iPhone, in tier order.

1
HIIT | Down DogShigher tier
Free + IAP · ★ 4.9 · 48,360 ratings · score 96
Generates HIIT workouts from over 1000 exercises, with adjustable length, intervals, difficulty and music.
2
7 Minute WorkoutShigher tier
Free download · ★ 4.8 · 14,334 ratings · score 92
Free iOS app with 7-minute bodyweight HIIT workouts at home, with voice guidance and video and text instructions.
4
HIIT • Workouts & TimerA
Free + IAP · ★ 4.8 · 31,087 ratings · score 85
Free HIIT workout app with 4-minute Tabata interval workouts, custom timers, and progress tracking.
5
Barry’s X: Best HIIT TrainingB
Free download · ★ 4.9 · 2,197 ratings · score 78
Free Health & Fitness app with on-demand cardio, lifting, and stretch workouts led by Barry's instructors.
6
Keelo - Strength HIIT WorkoutsC
Free + IAP · ★ 4.8 · 5,978 ratings · score 67
Free strength and conditioning app with personalized workouts, HD demo videos, and optional paid Premium coaching.
7
7 Minute Workout ChallengeF
$3.99 · ★ 4.7 · 5,940 ratings · score 43
Guides a 7-minute workout of 12 bodyweight exercises, each done for 30 seconds with 10-second rests, with no equipment.

What is the best alternative to Daily Cardio Workout - HIIT on iPhone?: HIIT | Down Dog, S tier, #1 in hiit workouts.
Is there a free alternative to Daily Cardio Workout - HIIT?: Yes: HIIT | Down Dog (S tier, #1) is free to download, with in-app purchases.
Does anything rank above Daily Cardio Workout - HIIT?: Yes. 2 apps rank above it in hiit workouts: HIIT | Down Dog (#1), 7 Minute Workout (#2).