What is the best alternative to Zwift Companion on iPhone?

Camp Gladiator, S tier, #1 in social workouts.

Is there a free alternative to Zwift Companion?

Yes: Camp Gladiator (S tier, #1) is free to download, with in-app purchases.

Yes. 3 apps rank above it in social workouts: Camp Gladiator (#1), Rumble Boxing - Group Fitness (#2), SugarWOD (#3).

Zwift Companion is B tier, #4 of 6 in social workouts. Here is everything that competes with it on iPhone, in tier order.

1
Camp GladiatorShigher tier
Free + IAP · ★ 4.9 · 11,889 ratings · score 83
Group fitness app with live workout classes led by certified Personal Trainers, with new workouts starting every 5.
2
Rumble Boxing - Group FitnessB
Free · ★ 4.8 · 5,306 ratings · score 76
Book Rumble full-body group fitness classes, join waitlists, find studios, track progress with Apple Health and earn.
3
SugarWODB
Free · ★ 4.9 · 90,791 ratings · score 72
Workout tracking app for CrossFit-style athletes and affiliate gyms, with WOD posting, PR tracking, and community.
5
Sweatpals: Fitness Near YouC
Free · ★ 4.9 · 5,561 ratings · score 69
Find and host fitness and wellness classes, events and retreats near you, with chat and ticketing for hosts and pals.
6
Echelon FitC
Free + IAP · ★ 4.4 · 8,352 ratings · score 65
Free fitness app with live, on-demand and scenic classes for cycling, rowing, running, strength training and yoga.

What is the best alternative to Zwift Companion on iPhone?: Camp Gladiator, S tier, #1 in social workouts.
Is there a free alternative to Zwift Companion?: Yes: Camp Gladiator (S tier, #1) is free to download, with in-app purchases.
Does anything rank above Zwift Companion?: Yes. 3 apps rank above it in social workouts: Camp Gladiator (#1), Rumble Boxing - Group Fitness (#2), SugarWOD (#3).