Posts Tagged ‘android market’

App Tracker and Chord Reader go open-source

I recently open-sourced two of my Android apps – App Tracker and Chord Reader. You can find the code on GitHub.

I open-sourced them for very different reasons, although the catalyzing events were similar. In both cases, I had a request from a fellow dev for more information about the app, which made me question why I was keeping it closed-source in the first place. And in both cases, I couldn’t find a good reason to keep the code private.

App Tracker

But in a broader sense, the two apps mean very different things to me. App Tracker was a project that I poured a lot of effort into, but which turned into an unmitigated failure, with only 294 active users (and less than 4,000 downloads) after almost two years on the Android Market. It’s kind of embarrassing to admit now, but at the time I was writing it, I actually thought App Tracker would be my ticket into doing freelance app development as a full-time gig – hence the laughable premium version. Ultimately, though, the app suffered from bad design and bad marketing (can you guess what it does from the name and icon?), and it never really took off. So in this case, opening up the source means acknowledging my failure and cutting my losses. It’s a humbling moment.

Chord Reader

Chord Reader, on the other hand, was an app that I barely put any effort into, and against my expectations became pretty successful, with over 35,000 downloads (and 10,000 active users) after about a year. It’s even made me a modest amount of money from the AdMob campaign (about $100), although I put in the ads more out of curiosity than anything. I never really found the time or interest to keep maintaining this app, though, so it ended up becoming something of a neglected stepchild to me. There were lots of requests for new features (autoscroll, set lists, bluetooth integration), but for some reason I just couldn’t muster up the enthusiasm to implement them. So in this case, opening up the source means releasing my app to the community, where hopefully it will find more dedicated contributors. It also means getting rid of the ads (since there’s no point in having ads in an open-source app), which I’m actually relieved to do, because they weren’t making me enough money to justify uglifying up the UI.

Of course, a lot of code gets open-sourced, and a lot of it gets lost in the abyss of endless cyberspace. There’s no point in making a big show about releasing this code without explaining a bit about why anyone should bother looking at it. So here’s my brief run-down:

App Tracker reads the system logs (“logcat”) in a background Service and notes when other apps are being launched, which allows it to keep usage statistics. It should be interesting for anyone looking to write an app to detect when a third-party app has been started (which was the question from a fellow dev that prompted me to open-source it). For instance, all of the various “protect my apps with a password” security apps use this technique. Be forewarned, though: these methods are faulty, given that the Android OS treats with suspicion any Service that tries to run 24/7, and may kill your Service without warning.

Chord Reader reads chord charts downloaded from sites like and, parses the text, and displays information about the chords, including various guitar fingerings. The most interesting part is the system of regexes (really, a grammar) to parse the chords and determine, for instance, that “Abmaj7” and “G#M7” both mean the same thing: “A-flat, major quality, 7th added.” A good place to see this in action is the unit tests. Music geeks should get a kick out of it. And of course, anyone who just wants to contribute to the project (like the dev who first contacted me and suggested open-sourcing it) is welcome to create branches and pull requests on GitHub.

Oh, and in case I haven’t made it clear elsewhere, when I open-source something on GitHub, please assume that the license is the WTFPL license, or some other very permissive open-source license. I honestly don’t care what you do with the code, although hopefully you’ll be nice about it and give me credit. Happy coding!

CatLog is #1!

My goal with CatLog was to write the best darned Logcat app for Android, and in that regard I think I succeeded. But as long as the adequate but inferior aLogcat was ahead in the search results for “logcat,” I felt like my work was incomplete. After all, most people will just download the first app in the list without trying any others. How can I really say that I’ve written the “best Logcat app for Android,” when it’s not most people’s first choice?

Starting sometime this month, though, it finally happened – CatLog now shows up first in a search for “logcat” on the Android Market:

I’m ecstatic that my app is finally getting the recognition I think it deserves, but, to be honest, I’m also kind of puzzled as to why it suddenly managed to nudge ahead of aLogcat. Comparing the Market statistics of the two apps side-by-side, it’s not clear what makes CatLog stand out:

CatLog aLogcat
Released: Aug. 2010 Nov. 2009 (?)
Downloads: 10,000-50,000 100,000-500,000
Reviews: 587 1,683
Rating: 4.7 4.6
Updated: August 14, 2011 March 6, 2011
Android Version: 1.5 and up 1.5 and up
Category: Tools Tools
Size: 323k 39k
Price: Free Free
Content Rating: Everyone Everyone

There doesn’t seem to be a big difference in the ratings (4.7 vs. 4.6), and aLogcat has a considerably higher number of downloads and reviews. So what changed? I think this blog post might provide a clue. It seems that, besides downloads and ratings, Google’s ranking algorithm also takes into consideration the retention rate of an app – i.e. how many users actually keep the app installed, as opposed to those who just download it.

It’s impossible for me to know what aLogcat’s retention rate is, because Google doesn’t make that information public. But I do know that CatLog has 40,834 downloads and 15,487 active users, which gives it a retention rate of 38%. This is the highest retention rate out of my most popular apps (30% for Chord Reader, 18% for Japanese Name Converter, and 20% for Pokédroid), so I’m guessing it’s also higher than whatever aLogcat has. Considering that aLogcat was released almost a year before CatLog, maybe it initially attracted a large user base that later started flocking to my app? Who knows.

Alternatively, it could be the fact that I’ve recently updated CatLog, whereas aLogcat hasn’t been updated since March of 2011. If that’s the case, then aLogcat could quickly regain the lead by just releasing an update. This seems unlikely, though, given that such a system would be easily gameable by just releasing a new update every day. As I noted in a previous post, those kinds of shenanigans made the “Just In” section of the Android Market practically useless, so Google eventually nipped that practice in the bud.

Whatever the reason, it’s nice to see that quality apps do eventually drift to the top. Similarly, I’ve watched one of my other apps, KeepScore, jump from 11th to 3rd in a search for “score keeper.” I’m hoping that, by just being the quiet valedictorian in the back of the class, it can eventually make it to the top. CatLog proves that that’s possible.

State of the Android app union

I thought it might be useful to report on how all my apps are doing on the Android Market, in terms of downloads and active users. Hopefully this information will be helpful for someone looking to write their own app, or wondering what their chances of success are.

It’s worth mentioning that I’ve never marketed any of my apps, except for a short “house ad” campaign I did in Chord Reader to promote KeepScore. App development is a hobby for me, so I’ve found it more interesting to just release my apps into the wild and see whether they sink or swim. I’ve relied almost solely on the Android Market and word-of-mouth to build up my user base.

This may have worked better when I first started writing apps, which was around March of 2010, when Android was still in its infancy. Back then, the Android Market had less than 20,000 total apps, so you could get a decent amount of visibility by simply publishing your app. Today, the Android Market boasts over 250,000 apps, so it’s much easier to get lost in the crowd.

My Personality Type

For instance, when I released my second app, My Personality Type, in March of 2010, it was able to gain 3,000 downloads in a single week without any advertising. Most likely this is just because personality tests are fun, mine was free, and it was also only the second or third of its kind to be released on the Market. The app was later removed due to a takedown request from psychologist David Keirsey, so there’s no way of knowing if it could have maintained that stellar rate of growth, but it’s pretty impressive nonetheless. (Yes, Pokédroid was not my first run-in with copyright issues. I tried to work out a licensing agreement with Dr. Keirsey, but eventually he stopped responding to my emails.)

By comparison, my most recent app, KeepScore, has grown much more slowly. KeepScore only broke 1,000 downloads very recently, even though it’s been on the Market for almost two months, and despite the fact that I promoted it through house ads (where it got 8,091 impressions and 243 clicks). I’m guessing this is because the Android Market is already saturated with tons of score-keeping apps, so KeepScore doesn’t even show up in the top 10 in a search for “score,” “score keeper”, etc. Even though it’s the best of the bunch, it’s hard to stand out over apps that have been around longer, with more downloads and more reviews.

In general, though, I’ve found that the best determiners of an app’s success in the Market are 1) search engine optimization, 2) constant updates, and 3) short, easily understandable app summaries. I’ll describe each one in turn.

Search results for "score keeper."

Search engine optimization is important for the obvious reasons. Most users are going to discover your app by searching for some problem they’re trying to solve – “save battery,” “calorie counter,” “weather widget,” etc. Try to think of what need your app fulfills, and be sure to include those terms in your Android Market description. I always just add a section at the end where I write “seo:” and then list a bunch of terms related to the app.

Constant updating might not be something you’d imagine would contribute much to an app’s success, but anyone who’s worked in Android development long enough can testify to this. Back in the old days, this technique was enormously effective, because the Android Market app had a prominent “Just In” page that simply listed the most recently released or updated apps. For this reason, you’d often see spam apps (such as “Sexy Hot Girl #12”) releasing a new version every day, perhaps under the imaginative title of “version-20100614”. Anybody could just change a string, release a new version of their app, and watch the number of downloads spike.

Google seems to have cracked down on this practice since then, and the new Market app doesn’t even include a “Just In” page. Instead we now have “Top New Paid,” “Top New Free,” and “Trending,” which seem relatively free of spam. But updating from time to time can still be a boon to your app’s success. Users love getting updates, and when the updates stop rolling in, they tend to lose interest in your app and uninstall it. Go long enough without any updates, and you may even start hemorrhaging users. (We’ll see an example of this later.)

Search results for "logcat."

And finally, short, easily understandable app summaries are a crucial part of promoting your app through the Market. I believe most users will decide whether or not to install your app based on a glance at the search results, which means the icon and the name are key. The description, the reviews, and even the star rating are of secondary importance, in my opinion. (The star rating is almost meaningless, because all halfway decent apps will have at least 4 stars.)

So when you design your app, you need to ask yourself: 1) Is the icon attractive, and does it hint at the app’s functionality? and 2) Is the name simple, and does it effectively communicate what the app does? For illustration, I’ll point out that aLogcat beats out my own app, CatLog, by this measure. CatLog has a cute icon (which many users have complimented me on!), but I’ll admit it requires a little bit of extra mental effort to figure out what the app does. CatLog still has fewer downloads than aLogcat.

All of these are just tips based on my own personal experience, which means they’re mostly hunches and guesswork. Make of them what you will. But of course, the Android Market also provides us with some wonderful reporting tools, so I have some hard data to offer as well!

So without further ado, here’s the current state of all my apps in Android Market, in the order I wrote them. I report the total number of downloads, as well as the number of active users (i.e. installed copies of the app). Each graph shows the change in active users since January of 2011, which is when Google started providing these detailed statistics. You can ignore sudden spikes in the graph – I think those are bugs in the reporting tool.

Japanese Name Converter

Released March 2010
7,464 active users (19%)

My first app, which I never updated beyond version 1.0, is still fairly popular. Its popularity also seems to be pretty constant, since I imagine most people download it, get a kick out of it, and then uninstall it soon afterwards. That doesn’t bother me much, though, since this was basically just a “Hello World” app for me.

My Personality Type

Released March 2010
287 active users (8%)

As I noted above, My Personality Type only spent one week on the Android Market, due to a takedown notice from the author of the test. (I actually based this app on an assignment from one of my undergraduate computer science classes, so I didn’t know the test was under copyright.) Given it’s been off the Market for a year, I’m kind of amazed the app still has any active users at all.


Released April 2010
125,576 active users (27%)

This chart still breaks my heart a little. The sudden bump in March corresponds to when I released the update for Pokémon Black/White, and the dip in June, of course, corresponds to when I removed the app from the Android Market due to a takedown notice from The Pokémon Company. At its height, it had 170,000 active users.

Offline Browser

Released June 2010
2,820 active users (16 %)

I wrote this app while I was attending the 2010 NAACL conference, because I wanted to be able to browse the conference proceedings, which were distributed as raw HTML and PDF files, on my phone. This app didn’t hold much interest for me afterwards, so I never looked back. (By the way, here’s my paper from that conference.)

App Tracker

Released July 2010
344 active users (10%)

With only 3,000 downloads over the course of a full year, App Tracker is a certified dud. As I was developing it, I actually believed it was going to be my breakthrough app, and that the revenue from the Premium version would allow me to quit my day job and do app development full-time. Unfortunately, the graveyard of lost ambitions is littered with such failures, and App Tracker never really got off the ground.


Released August 2010
10,330 active users (41%)

Ah, CatLog – the phoenix that rose from the ashes of App Tracker. After App Tracker’s failure, I refashioned its log-reading component into a straight-up Logcat app, and now CatLog perseveres as my third-most popular app. In fact, it’s probably the app I’m most proud of after Pokédroid.

Chord Reader

Released October 2010
11,607 active users (38 %)

It’s a shame I never found this app very compelling to work on, because it’s actually my most popular app on the Market (now that Pokédroid is gone). I’m not really sure why it started bleeding users in late June, but if I had to guess, I’d say it’s because I haven’t updated it much over the past year. Like I mentioned above, users tend to lose interest when you don’t update, and I think that’s especially true when there are much-needed features they keep clamoring for. (In my case, users keep asking for an auto-scroll feature and setlists.)


Released June 2011
873 active users (72 %)

I would really, really like to see this app succeed more than it has. My goal with KeepScore was to create the end-all be-all best score keeper for Android, and in a sense I’ve failed simply because the app still doesn’t have much visibility in the Android Market. As I mentioned above, it doesn’t even come up in the top 10 in searches for “score” or “score keeper,” meaning that most users will probably never find it, and instead settle for an inferior app. I’m not sure what to do, though, other than wait for it to gain more downloads and ratings. I have no control over Google’s search rankings.

So that concludes my app-by-app report. But because it’s a lot of data to take in individually, I also created some charts comparing all the apps side by side:

Total downloads and active users

Total downloads and active users

This chart shows the total number of downloads and active users (as of today) per app. Obviously Pokédroid is an order of magnitude more popular than my other apps, so I also created a log-based version of the same chart:

Total downloads and active users (log)

Total downloads and active users (log)

Here it’s a little easier to compare the non-Pokédroid apps. Chord Reader, CatLog, and Japanese Name Converter are all reasonably successful, whereas Offline Browser and App Tracker are less so. With KeepScore and My Personality Type, it’s difficult to compare, because they’ve spent much less time on the Market than the others. So I also went ahead and created a chart showing the total number of downloads and active users divided by the approximate number of days spent in the Market:

Downloads and active users per day spent in Market

Here it’s easier to see which apps were more popular on a day-to-day basis. The most surprising finding is that My Personality Type apparently had more potential than I thought. Even though it was only on the Market for one week, it looks like it could have been as popular as Pokédroid if it hadn’t been taken down. (Funny that my most successful apps are also the ones that get targeted for copyright infringement! Take note, kids: you walk a fine line when you reuse other people’s content.)

And here’s the same graph with a log-based y-axis:

Downloads and active users per day spent in Market (log)

So there you have it. Of the apps I still have on the Market, Chord Reader, Japanese Name Converter, and CatLog are the most popular. Offline Browser and KeepScore take up the second tier, whereas App Tracker is an unmitigated failure. (I couldn’t even show App Tracker’s active users per day on this chart, because the value was less than 1, meaning the log value actually went negative.)

I wish I could say there was a way to know in advance whether an app is going to be a hit or a miss, but I think the Android Market is just too unpredictable for that. You really can’t know how popular an app is going to be until you put it out there. For me, though, this is the excitement of app development. More so than with any other kind of software development, you get immediate confirmation of whether or not people find your app useful. So if nothing else, it’s fun to throw darts at the board and see what sticks.