What is the best alternative to Dua & Azkar on iPhone?

Azkar - اذكار : Athan & Prayer, S tier, #1 in adhkar.

Is there a free alternative to Dua & Azkar?

Yes: Azkar - اذكار : Athan & Prayer (S tier, #1) is free to download, with in-app purchases.

Yes. 2 apps rank above it in adhkar: Azkar - اذكار : Athan & Prayer (#1), Adhkar - Morning & Evening (#2).

Dua & Azkar is B tier, #3 of 7 in adhkar. Here is everything that competes with it on iPhone, in tier order.

1
Azkar - اذكار : Athan & PrayerShigher tier
Free + IAP · ★ 4.7 · 47,103 ratings · score 96
Islamic app offering Athkar, Qur'an reading and audio, prayer times, Qibla direction, and a Tasbih counter.
2
Adhkar - Morning & EveningAhigher tier
Free download · ★ 4.4 · 3,191 ratings · score 89
IOS app for morning and evening adhkar with guided reading, a misbaha counter, audio, Hisn al-Muslim duas, and a Quran.
4
Adhkar AppC
Free · ★ 4.9 · 654 ratings · score 68
Free iOS app for tracking daily morning, evening and night adhkar, with location-based reminders and an optional…
5
iAzkar - آي أذكارD
Free · ★ 4.7 · 5,762 ratings · score 58
Arabic Islamic app that displays daily athkar in five sections, with background audio and morning and evening.
6
مؤذني - MoadeniF
$19.99 · ★ 4.8 · 3,179 ratings · score 43
Reference app for prayer times, Qibla direction and Athkar, listed on the App Store as Moadeni.
7
Hisn - حصنF
Free + IAP · ★ 4.8 · 1,965 ratings · score 42
Adhkar and supplications app based on the book Fortification of the Muslim, with Quran and Sunnah duas, audio.

What is the best alternative to Dua & Azkar on iPhone?: Azkar - اذكار : Athan & Prayer, S tier, #1 in adhkar.
Is there a free alternative to Dua & Azkar?: Yes: Azkar - اذكار : Athan & Prayer (S tier, #1) is free to download, with in-app purchases.
Does anything rank above Dua & Azkar?: Yes. 2 apps rank above it in adhkar: Azkar - اذكار : Athan & Prayer (#1), Adhkar - Morning & Evening (#2).