What is the best alternative to Tap Tempo Button on iPhone?

Auto BPM: Music Tempo Finder, S tier, #1 in tap tempo.

Is there a free alternative to Tap Tempo Button?

Yes: Auto BPM: Music Tempo Finder (S tier, #1) is free, with no in-app purchases.

Yes. 3 apps rank above it in tap tempo: Auto BPM: Music Tempo Finder (#1), Tap That Tempo (#2), GruKit: DJ Vinyl Scanner (#3).

Tap Tempo Button is F tier, #4 of the 7 tiered apps in tap tempo. Here is everything that competes with it on iPhone, in tier order.

1
Auto BPM: Music Tempo FinderShigher tier
Free download · ★ 4.7 · 1,906 ratings · score 92
Estimates the tempo (BPM) of music playing nearby by listening through the iPhone microphone, without tapping.
2
Tap That TempoAhigher tier
Free + IAP · ★ 4.7 · 1,176 ratings · score 83
A tap-based tool that measures the BPM of music by tapping along to the beat.
3
GruKit: DJ Vinyl ScannerChigher tier
Free download · ★ 5.0 · 3 ratings · score 61
Free iOS toolkit for vinyl DJs and collectors: song ID, turntable speed check, BPM tapping, barcode lookup and record.
5
Tap Tempo: BPM CounterF
$0.99 · ★ n/a · 0 ratings · score 25
Measures BPM by tapping along or listening with the microphone, and saves tempos on iPhone and Apple Watch.
6
Tap Tempo: BPM and Beat MatchF
Free + IAP · ★ n/a · 0 ratings · score 24
Tap along to a rhythm to measure its tempo in BPM, with a metronome, delay time converter and tap history log.
7
Tap Tempo BPMF
Free download · ★ 1.0 · 1 ratings · score 12
A tap tempo BPM counter that measures the tempo of music by tapping along to it.

What is the best alternative to Tap Tempo Button on iPhone?: Auto BPM: Music Tempo Finder, S tier, #1 in tap tempo.
Is there a free alternative to Tap Tempo Button?: Yes: Auto BPM: Music Tempo Finder (S tier, #1) is free, with no in-app purchases.
Does anything rank above Tap Tempo Button?: Yes. 3 apps rank above it in tap tempo: Auto BPM: Music Tempo Finder (#1), Tap That Tempo (#2), GruKit: DJ Vinyl Scanner (#3).