There is actually a MusicBrainz for Android app, which hasn’t received much (if any) love for a long time:
https://play.google.com/store/apps/details?id=org.musicbrainz.mobile
So if by “smartphone” you mean Android, perhaps you would be interested in helping with (or taking over?) maintenance of that app? 
I have borrow a smartphone once for the purpose that @ClaudeVernier describes as it happens that I would buy duplicates. I remember that crucial information was missing while browsing my collection and I had to fallback to the website collection page.
I don’t remember what was missing, it was something that would identify a specific edition, like catalogue numbers, track lists, I don’t remember.
I say that because if Claude has the same aim as me, there is hope. 
But unfortunately I do not have smartphone, so take it only as an advice.
I am a Microsoft technologies developer. I was planning on writing my App with the Cordova framework which makes application compatible with Android and iPhones, it is not a miracle framework that makes everything out of the box, but it can help to build apps for several platform with only one app.
I had a look at the code of the Android app, it is a quite large app and well documented but still my lack of knowledge of Android was revealed to me… I’d be happy to help but I don’t know how yet.
Cheers,
Claude
I found the Android app recently under the products menu on MusicBrainz, and was very excited about the possibility to look up releases by barcode while shopping. I think what it lacks is (like @jesus2099 said) the possibility to show more detailed information about releases and other entities in the app. So any work on the existing app or new projects would be great.
I’ve been experimenting with mobile app development lately, mostly in android studio which has some amazing tools for building aesthetically pleasing applications right out of the box. Although I wouldn’t call it overly simplistic by any means. I can’t really wrap my head around the larger example projects yet.
I’ve also used kivy a bit which allows for multi-platform mobile development in python. It’s much simpler and more approachable, but of course lacks the flair built in to android studio. That being said, it is more than possible to build a beautiful and functional application with kivy, which of course has the ability to run on any device. Some examples for your consideration: https://github.com/kivy/kivy/wiki/List-of-Kivy-Projects
Apache cordova sounds like a cool idea too @ClaudeVernier. That would also have the benefit of web functionality which could be used as a cool visual frontend to the musicbrainz db. I would super interested in helping out with the mobile project, regardless of the direction it takes… Is there a working list of features everyone would want in a new version? I haven’t used the other one, but I’ll try to check it out on my android emulator.
Or I don’t know, maybe a mobile version (via CSS or an alternate m.musicbrainz.org site) of the site?
Only barcode scanning would be lacking.
I think that barcode scanning is possible in js, although, intuitively, it seems more like a feature that belongs in an app. I was thinking something like soundhound-esque music identification, picard tagging, or even a mobile audioplayer for a users library. Other than itunes and streaming services, I’ve never really had a particularly memorable audio playback experience on a cell phone. It’d be really cool to build a sort of functional all-in-one audio application that people could actually customize or tweak how they wanted and contribute in a meaningful way to it’s development instead of just dealing with apple’s or any companies forced updates. Maybe I’m projecting my own project ideas onto this much more finite app though…
This is inevitable, surely?
Surprised it doesn’t exist yet (though I know everyone’s busy, no hate!), maybe it’s something I could have a look at sometime…
That makes two of us — the 2% (percentage of world population without cell phones) 
Actually, I was unaware of the existence of such an app.
What I do know is that Discogs (<- is it allright to mention this organization? ) recently launched their official iOS App see blog here
For features scroll down page.
Checkout my rough GUI prototype for a musicbrainz / social / music recommendation / media player app… all icons are unicode emojis… if you were wondering about the choices I made there…
actually, for me, what I’d want in a MusicBrainz app on my android is the ability to actually * tag* musicfiles.
Why? well because loading a bunch of files on the phone/downloading them from wherever (I’m sure bandcamp and soundcloud m.m has apps with features) and then only later discovering that it was badly tagged (and therefore messed up playing order etc.) and being able to fix that on the get-go instead of having to plug into a computer (that must have picard on it, so not just a random public one or anything. also to remember an USB cable.)
Or the situation where the way it’s tagged for musicplayer on computer, works havoc on phone.
For example does itunes let you set disc numbers and will play these separate and consequently, not so on a phone or mp3player - instead you get track 1 from disc 1 and then track 1 from disc 2 etc.
perhaps a “Mobile Picard” is a different project altogether ?
~cat
That’s an excellent point. I think I went a little crazy with the instagramified features and design and lost site of the whole point. xD Mobile music tagging is an essential tool. Bringing it to to mobile would be great. Even the google play page for the MB app has comments from users requesting that feature. I’ll definitely look into it! Thanks for the comment!
