BarlineSlow down music to learn it by ear
How Barline compares
Barline is an iPhone app for learning songs by ear: it slows down audio files you own without changing the key, finds their bars, beats, sections and key on the phone, and loops the exact bars you need. Some of this is in other apps too: Capo also finds bars and snaps loops to them, Moises lists AI-detected sections under Premium, and Amazing Slow Downer speeds a loop up and, like Barline, collects no data. Barline does all of these in one app. The others also run on iPad and Mac.
Who it suits
Barline is a good fit if
- You learn by ear from audio files you own (MP3, M4A, WAV, AIFF or FLAC), on an iPhone.
- You want the bar lines and sections found for you and loops snapped to them (Capo also finds bars and snaps loops to them; Moises lists AI-detected sections under Premium).
- You want the loop to speed itself up as you get it (Amazing Slow Downer does too, and Anytune with its Pro Pack, which needs the Basic Pack).
- You’d rather nothing was uploaded and no data collected (like Amazing Slow Downer, whose privacy label also reads Data Not Collected).
Another app may suit you better if
- You practise on an iPad or a Mac: all four have iPad and Mac versions (Moises in the same app, the others as separate apps).
- You want to separate the vocals, drums or bass: Moises does on its free plan, Anytune with its Studio Pack.
- You want songs from your Apple Music library: Amazing Slow Downer and Anytune play them; Barline imports files.
- You’d rather pay once (Amazing Slow Downer, £14.99) or keep a free version (Capo’s Free Edition).
- You need more than 40% to 120%: Amazing Slow Downer runs from 25% to 200%, Capo from 25% to 150%.
Side by side
From each app’s UK App Store page and website, checked on 15 October 2026. “Not listed” means we couldn’t find it there that day. Paid features say which plan.
| Feature | Barline | Amazing Slow Downer | Anytune | Capo | Moises |
|---|---|---|---|---|---|
| Price (UK) | £2.99 a month or £19.99 a year, first week free | £14.99 once | Free with ads; packs £1.99 to £6.99 | Free Edition; Pro £18.99 a year, or £1.99 or £4.99 a month; Platinum £44.99 a year | Free with limits; Premium £4.99 a month, £34.99 or £39.99 a year; Pro from £24.99 a month |
| Finds the bar lines and snaps loops to them | Yes | Not listed (set by hand) | Not listed (tempo only) | Yes | Shows bars; snapping not listed |
| Finds the song’s sections, one tap to loop one | Yes | Not listed | Not listed (your marks) | Not listed (you name them) | Yes, listed under Premium |
| Speeds a loop up as you repeat it | Yes | Yes | With the Pro Pack (£4.99, needs the £1.99 Basic Pack) | Not listed | Not listed |
| Moves the downbeat when you tap the one | Yes | Not listed | Not listed | Edits the beat grid; kept with Pro | Not listed |
| App Store privacy label | Data Not Collected | Data Not Collected | Data Used to Track You | Data Linked to You | Data Used to Track You |
| Runs on | iPhone | iPhone, iPad, Vision Pro; Mac, Windows and Android apps separate | iPhone, iPad, Vision Pro; Apple Watch with the Remote Control & Watch add-on (£4.99); Mac and Android apps separate | iPhone, iPad; Mac app separate (Free Edition) | iPhone, iPad, Mac, Apple TV, Vision Pro; Android, web |
What people ask for, and what Barline does
Loops that come round in time
People ask for a loop with no hiccup at the seam. Barline snaps both ends to the bar lines and plays the seam without a gap.
Bar lines on the wrong beat
Beat detection sometimes misplaces the one on a live recording. In Barline you tap along on the one and the bar lines, sections and loops follow.
No account, no upload
Some people would rather not send their recordings anywhere. Barline analyses each song on the phone, has no account and collects no data.
Questions
Is there an app that slows down music without changing the key?
Yes. Barline, Amazing Slow Downer, Anytune, Capo and Moises all do. In Barline speed runs from 40% to 120% and pitch is a separate control, up to twelve semitones either way.
Which app finds the bars and loops them for me?
Barline finds the bar lines, sections and key when you import a song and snaps every loop to the bars. Capo also finds bars and beats and snaps loops to them.
Can Barline slow down songs from Apple Music or Spotify?
No. Streamed tracks are copy-protected, so Barline works with audio files you own: MP3, M4A, WAV, AIFF or FLAC.
Does Barline upload my music?
No. The analysis runs on the iPhone, there is no account, and its App Store privacy label is Data Not Collected.
Does Barline work on iPad or Mac?
Barline is made for iPhone, with iOS 27 or later. Amazing Slow Downer, Anytune, Capo and Moises all have iPad and Mac versions (Moises in the same app, the others as separate apps).
Checked 15 October 2026. Other apps change; if something here is out of date, tell us.