We would like to thank the owners of the photos used in our app. Their information and the corresponding licences are listed bellow.

Trumpet
Trumpet 1 by Amanda44 is licensed under CC BY-SA 3.0
Trumpet 2 by Justin Brockie is licensed under CC BY 2.0
Trumpet 3 by Pxhere is licensed under CC BY 2.0
Trumpet 4 by Silviu Costin is licenced under Pexels License
Trumpet 5 by Charles Nadeau is licensed under CC BY 2.0

Clarinet
Clarinet 1 by Crisco 1492 is licensed under CC BY-SA 4.0
Clarinet 2 by Petrus Glas is licensed under CC BY-SA 4.0 
Clarinet 3 by Pxhere is licensed under CC0 1.0
Clarinet 4 by Ralf Schulze  is licensed  under CC BY 2.0
Clarinet 5 by Pxhere is licenced under CC0 1.0

Saxophone
Saxophone 1 by Sally V is licensed under CC BY-SA 4.0
Saxophone 2 by juantiagues is licensed under CC BY 2.0
Saxophone 3 by Pexels is licensed under CC0 1.0
Saxophone 4 by Pxhere is licensed under CC0 1.0
Saxophone 5 by Sally V is licensed under CC BY-SA 4.0

Bassoon
Bassoon 1 by Carl August Schaufler is licensed under CC0 1.0
Bassoon 2 by Giosue Esposito is licensed under CC0 1.0
Bassoon 3 by ACE Foundation is licensed under CC BY 2.0
Bassoon 4 by Thorsten Krienke  is licensed under CC BY 2.0
Bassoon 5 by  ACE Foundation is licensed under CC BY 2.0

Violin
Violin 1 by Creative Tools is licenced under CC BY 2.0
Violin 2 by  菜森_Rister is licensed under PRF license
Violin 3 by Eric Golub is licenced under CC BY 2.0
Violin 4 by I'often is licensed under PRF license
Violin 5 by Curran Kelleher is licenced under CC BY 2.0

Piano
Piano 1 & 2 by Steinway & Sons is licensed under CC BY-SA 3.0
Piano 3 by Pixabay is licensed under  CC0 1.0
Piano 4 by 武轩 is licensed under PRF license
Piano 5 by DailyMediaStudio is licensed under CC BY-SA 4.0

Oboe
Oboe 1 by Hustvedt is licensed under CC BY-SA 3.0
Oboe 2 by Jacob Denner is licensed under  CC0 1.0
Oboe 3 by Byron Howes  is licensed under CC BY-ND 2.0
Oboe 4 by Alexei Zoubov has been released into public domain
Oboe 5 by samuraijohnny is licenced under CC BY 2.0

Classical guitar
Classical guitar 1 by Boubbt Official is licenced under CC BY 2.0
Classical guitar 2 by Trude Bergheim Mikkelsen is licensed under CC BY-SA 4.0
Classical guitar 3 by Pixabay is licensed under  CC0 1.0
Classical guitar 4 by Gianni Sarti is licenced under CC BY 2.0
Classical guitar 5 by Danica Bijeljac is licensed under CC BY-SA 3.0

Tuba
Tuba 1 by Charles Hutchins  is licenced under CC BY 2.0
Tuba 2 by Wolfie  has been released into public domain
Tuba 3 by IIP Photo Archive is licensed under  CC0 1.0
Tuba 4 by Garry Knight  is licenced under CC BY 2.0
Tuba 5 by Prayitno is licenced under CC BY 2.0

Cello
Cello 1 by nosha is licensed under CC BY-SA 2.0
Cello 2 by Gabriel Hess  is licensed under CC BY-SA 2.0
Cello 3 by Gabriel Ureña is licenced under CC BY 2.0
Cello 4 by Irv Kagan is licensed under CC BY-ND 2.0
Cello 5 by Tomás Del Coro is licensed under CC BY-SA 2.0

Trombone
Trombone 1 by Josef Plch has been released into public domain
Trombone 2 by the Met Museum is licensed under CC BY-SA 3.0
Trombone 3 by Gabrielt4e is licensed under GFDL
Trombone 4 by  ACE Foundation is licensed under CC BY 2.0
Trombone 5 by The United States Army Band is licensed under CC BY 2.0

Flute
Flute 1 by 20000000384 is licensed under PRF license
Flute 2 by Warner Music Group Germany Holding GmbH is licensed under CC BY-SA 4.0
Flute 3 by Amadís is licensed under CC BY-SA 3.0
Flute 4 by ACE Foundation is licensed under CC BY 2.0
Flute 5 by Mark Bonica is licensed under CC BY 2.0

Harmonica
Harmonica 1 by eurok is licensed under CC BY 2.0
Harmonica 2 by AlixSaz is licensed under CC BY-SA 4.0
Harmonica 3 by Nicolas Buffler is licensed under CC BY 2.0
Harmonica 4 by shannonpatrick17 is licensed under CC BY 2.0
Harmonica 5 by Ken FUNAKOSHI is licensed under CC BY-SA 2.0

Drum
Drum 1 by Yannick Weiler is licensed under CC BY 2.0
Drum 2 by Vladimir Morozov is licensed under CC BY 2.0
Drum 3 by Dejan Krsmanovic is licensed under CC BY 2.0
Drum 4 by Iain Cameron is licensed under CC BY 2.0 
Drum 5 by Randy Robertson is licensed under CC BY 2.0

Melodica
Melodica 1 by 鍵盤ハーモニカ is licensed under CC BY 2.0
Melodica 2 by Ukulele is licensed under CC BY-SA 3.0
Melodica 3 by ウィキ太郎(Wiki Taro) has been released into public domain
Melodica 4 by Bennett is licensed under CC BY-SA 2.0
Melodica 5 by Bob Doran  is licensed under CC BY 2.0

Ukulele
Ukulele 1  by Johannes Weber is licensed under CC BY 2.0
Ukulele 2 by Fhgitarre is licensed under CC BY 2.0
Ukulele 3  by Mariano Angius is licensed under CC BY 2.0
Ukulele 4 by Dean Wissing is licensed under CC BY-SA 2.0
Ukulele 5  by Charles Mims is licensed under CC BY 2.0

Metallophone 
Metallophone 1 by cyanide45 is licensed under CC BY 2.0
Metallophone 2 by Méline Waxx is licensed under Pexels license
Metallophone 3 by Pixabay is licensed under Pexels license
Metallophone 4 by Tom Page is licensed under CC BY-SA 2.0
Metallophone 5 by Quinn Dombrowski is licensed under CC BY-SA 2.0

Recorder
Recorder 1 by LovePik is licensed under CC0 1.0
Recorder 2 by Marco Verch is licensed under CC BY 2.0
Recorder 3 by Pxhere is licensed under CC0 1.0
Recorder 4 by Victoria Borodinova is licensed under Pexels license
Recorder 5 by Pymouss is licensed under CC BY-SA 3.0

Lyre
Lyre 5 by Amber Strocel is licensed under CC BY-ND 2.0

Castanets
Castanets 1 by TheMexican has been released into public domain
Castanets 2 by Missouri History Museum has been released into public domain
Castanets 3 by Lernestorod is licensed under Pixabay License
Castanets 4 by montuno is licensed under CC BY-SA 2.0
Castanets 5 by SD Dirk is licensed under CC BY 2.0

Triangle
Triangle 5 by julimagalhaes is licensed under Pixabay License

Tambourine
Tambourine 1 by Pxhere is licensed under CC0 1.0
Tambourine 2 by Drumsontheweb is licensed under CC BY-SA 3.0
Tambourine 3 by Nacho is licensed under CC BY 2.0
Tambourine 5 by Mark Gstohl is licensed under CC BY 2.0

Maracas
Maracas 1 by Luis Alvaz is licensed under CC BY-SA 4.0
Maracas 2 by Luis Alvaz is licensed under CC BY-SA 4.0
Maracas 3 by Rusty Clark ~ 100K Photos is licensed under CC BY 2.0
Maracas 5 by Bryan Ledgard is licensed under CC BY 2.0

Pan flute
Pan flute 1 by LovePik is licensed under CC0 1.0
Pan flute 2 by Pxhere is licensed under CC0 1.0
Pan flute 3 by LovePik is licensed under CC0 1.0
Pan flute 4 by Laima Gūtmane is licensed under CC BY-SA 3.0
Pan flute 5 by 總統府 is licensed under CC BY 2.0

Acoustic guitar
Acoustic guitar 1 by LovePik is licensed under CC0 1.0
Acoustic guitar 2 by Loco Steve is licensed under CC BY 2.0
Acoustic guitar 3 by Your Best Digs is licensed under CC BY 2.0
Acoustic guitar 4 by Jonathan Kos-Read is licensed under CC BY-ND 2.0
Acoustic guitar 5 by LovePik is licensed under CC0 1.0

Electric guitar
Electric guitar 1 by LovePik is licensed under CC0 1.0
Electric guitar 2 by Larry Ziffle  is licensed under CC BY 2.0
Electric guitar 3 by Kuba Bożanowski is licensed under CC BY 2.0
Electric guitar 4 by Pixabay  is licensed under Pexels license
Electric guitar 5 by Loren Javier is licensed under CC BY-ND 2.0

Electric bass
Electric bass 1 by LovePik is licensed under CC0 1.0
Electric bass 2 by Alexander Lesnitsky is licensed under CC0 1.0
Electric bass 3 by Shunichi kouroki  is licensed under CC BY 2.0
Electric bass 4 by Bruno is licensed under CC BY-SA 3.0
Electric bass 5 by Basheer Tome is licensed under CC BY 2.0

Keyboard
Keyboard 1 by Moribunt is licensed under CC BY-SA 3.0
Keyboard 2 by Alex Borland is licensed under CC0 1.0
Keyboard 3 by Mattgirling is licensed under CC BY-SA 3.0
Keyboard 4 by Lindz Graham is licensed under CC BY 2.0
Keyboard 5 by Aureliomoraes30 is licensed under CC BY-SA 3.0

Drum kit
Drum kit 2 by Pxhere is licensed under CC0 1.0
Drum kit 3 by Michael Coghlan is licensed under CC BY-SA 2.0
Drum kit 4 by Iyyaka Nastain is licensed under CC BY 2.0
Drum kit 5 by LovePik is licensed under CC0 1.0

Accordion
Accordion 1 by Monika Fischer is licensed under CC BY 2.0
Accordion 2 by Bigbluefish has been released into public domain
Accordion 3 by Uberprutser is licensed under CC BY-SA 3.0
Accordion 4 by Per Palmkvist Knudsen is licensed under CC BY-SA 2.5
Accordion 5 by Paul Hudson is licensed under CC BY 2.0

Mandolin
Mandolin 1 by Angelo Mannello is licensed under CC0 1.0
Mandolin 2 by Villanueva has been released into public domain
Mandolin 3 by David Hilowitz is licensed under CC BY 2.0
Mandolin 4 by Ted and Jen  is licensed under CC BY 2.0
Mandolin 5 by spoilt.exile is licensed under CC BY-SA 2.0

Cajón
Cajón 1 by castilloivan.f is licensed under CC BY-SA 4.0
Cajón 2 by Ravenest13 is licensed under CC BY-SA 4.0
Cajón 3 by Daniel Ogden is licensed under CC BY-SA 3.0
Cajón 5 by Gluckstadt is licensed under CC BY-SA 3.0

Banjo
Banjo 2 by Larry Lamb is licensed under CC BY-SA 2.0
Banjo 3 by LovePik is licensed under CC0 1.0
Banjo 4 by Gratisography is licensed under Pexels license
Banjo 5 by Wesley Fryer is licensed under CC BY-SA 2.0

Marimba
Marimba 2 by Marimbaone is licensed under CC BY-SA 3.0
Marimba 3 by Mrkhlopov is licensed under CC BY-SA 4.0
Marimba 4 by Thorsten Krienke is licensed under CC BY-SA 2.0
Marimba 5 by Heather Harvey is licensed under CC BY-SA 2.0

Harp
Harp 1 by Salvi Harps is licensed under CC BY-SA 4.0
Harp 2 by Sébastien Érard has been released into public domain
Harp 4 by Raymond Klaassen is licensed under CC BY-ND 2.0
Harp 5 by Thorsten Krienke is licensed under CC BY-SA 2.0

Bongos
Bongos 1 by Pxhere is licensed under CC0 1.0
Bongos 2 by Cralize is licensed under CC BY-SA 3.0
Bongos 3 by Vladimir Morozov is licensed under CC BY 2.0
Bongos 5 by Khaldun albaz is licensed under CC BY-SA 4.0

Oud
Oud 1 by Céréales Killer is licensed under CC BY-SA 3.0
Oud 2 by The Metropolitan Museum of Art  is licensed under CC0 1.0
Oud 3 by Iranian Oud Player is licensed under CC BY-SA 4.0
Oud 4 by Enas El Masry is licensed under CC BY-SA 4.0
Oud 5 by Pixabay is licensed under Pexels license

Sitar
Sitar 1 by Sathyadeep has been released into public domain
Sitar 2 by Andrew Plumb is licensed under CC BY-SA 2.0
Sitar 3 by Ustad Nishat Khan is licensed under CC BY-SA 4.0
Sitar 4 by Nandanupadhyay is licensed under CC BY-SA 3.0
Sitar 5 by Jean-Pierre Dalbéra is licensed under CC BY 2.0

Bouzouki
Bouzouki 1 by Arent is licensed under CC BY-SA 3.0
Bouzouki 2 by Villanueva is licensed under CC BY-SA 3.0
Bouzouki 3 by Titanas is licensed under CC BY-SA 2.0
Bouzouki 4 by Ilias Theodoropoulos is licensed under CC BY 2.0
Bouzouki 5 by Jarosław Roland Kruk is licensed under CC BY-SA 3.0

Balalaika
Balalaika 2 by Pxhere is licensed under CC0 1.0
Balalaika 3 by juantiagues is licensed under CC BY-SA 2.0
Balalaika 4 by Pixabay is licensed under CC0 1.0
Balalaika 5 by tomislavmedak is licensed under CC BY 2.0

Didgeridoo
Didgeridoo 2 by LovePik is licensed under CC0 1.0
Didgeridoo 3 by Seantelle92 is licensed under CC BY-SA 4.0
Didgeridoo 4 by Fæ is licensed under CC BY-SA 3.0
Didgeridoo 5 by Noel Feans is licensed under CC BY 2.0

Saz
Saz 3 by Lukas007 has been released into public domain
Saz 4 by Raimond Spekking is licensed under CC BY-SA 4.0
Saz 5 by S Pakhrin is licensed under CC BY 2.0

Chinese lute
Chinese lute 1 by LovePik is licensed under PRF license
Chinese lute 2 by 拼却的一醉 is licensed under PRF license
Chinese lute 3 by IQRemix is licensed under CC BY-SA 2.0
Chinese lute 4 by Jean-Pierre Dalbéra is licensed under CC BY 2.0
Chinese lute 5 by by LovePik is licensed under CC0 1.0

Chinese violin
Chinese violin 1 by LovePik is licensed under PRF license
Chinese violin 2 by 拼却的一醉 is licensed under PRF license
Chinese violin 3 by Peter Griffin is licensed under CC0 1.0
Chinese violin 4 by Simon Blackley is licensed under CC BY-ND 2.0
Chinese violin 5 by gaelx is licensed under CC BY-SA 2.0

Chinese zither
Chinese zither 1 by LovePik is licensed under PRF license
Chinese zither 2 by LovePik is licensed under PRF license
Chinese zither 3 by 文心雕龙 is licensed under PRF license
Chinese zither 4 by Gary Stevens is licensed under CC BY 2.0
Chinese zither 5 by Pxhere is licensed under CC0 1.0

Darbuka
Darbuka 1 by greensheepred is licensed under CC BY-SA 2.0
Darbuka 3 by Lukáš Perný is licensed under CC BY-SA 3.0
Darbuka 4 by Elekes Andor is licensed under CC BY-SA 4.0
Darbuka 5 by Thorsten Krienke is licensed under CC BY-SA 2.0

Harmonium
Harmonium 2 by Niranjan Arminius is licensed under CC BY-SA 2.0
Harmonium 3 by Frédéric BISSON is licensed under CC BY 2.0
Harmonium 4 by Christian Jansen  is licensed under CC BY 3.0
Harmonium 5 by Iqbal7282 is licensed under CC BY-SA 3.0

Bagpipes
Bagpipes 2 by Mushummel is licensed under CC0 1.0
Bagpipes 3 by Pxhere is licensed under CC0 1.0
Bagpipes 4 by Werner Bayer is licensed under CC BY 2.0
Bagpipes 5 by Daniel Stockman is licensed under CC BY-SA 2.0