5 ASO Experiments to Understand the App Store

Maximilian Lehmannby 

10 min read

The App Store algorithm is a complex and ever-growing black box.

So even though we don’t claim to have decoded the App Store in any shape or form, we hope the results from this experiment might be valuable for your ASO strategy.

To explain our steps, we will visualize each point of our case study with our app 7 Minute workout. This will help you get a better idea on how we approached each experiment.

Requirements for the experiments to get started:

  • Only organic downloads
  • We did not incentive users to rate the app (in fact, over the whole time range the app had 0 ratings).
  • We used AppTweak’s ASO platform to track and measure the results of our experiments.

Experiment 1

How keywords in description affect your app’s ranking?

Many rumors arose to explain the phenomenon of the latest big update.

From the indexing of the App Store description, to Apple associating the keywords of your app to similar ones, there were many hypotheses on what really happened.

In order for us to not just build our strategy on assumptions, we reconstructed the following scenarios based on these 2 questions:

  • Do keywords cause rankings if you place them in the description?
  • Do keywords correlate with existing rankings and improve them if included in the description?

To test the first scenario (1), we have included very generic keywords to the text, which were not in the title or keyword field.

Here is what happened:

Keywords Number of words in the text before Rankings before Number of words in the text after Rankings after
Fitness 0 5
Healthkit 0 4
Life 0 4
Sweat 0 2
Training 0 1

Even though we optimized the keywords “fitness,” “healthkit,” “life,” “sweat,” and “training,” and included them in the app description strategically, we did not manage to get our app rank for either of them.

But what happens if you want to improve your existing ranking by optimizing the app description?

To try answering this question (2), we added some keywords to our German description, which we already covered in our title & keyword field, and got the following results:


Keywords No. of words in the text before Rankings before No. of words in the text after Rankings after
training 2 442 6 453
intervall 0 148 5 134
intervall-training 0 34 5 34


We filled the app description quite a bit in order to test if keywords in the description would improve the keyword rankings in any way. In this case, even with a decent keyword density, we could not get any real improvement in the rankings.

The on-page optimization of your app’s description on the App Store does not improve your rankings in the same way it does in Google Play, for example.

Nevertheless, you should notice that your App Store description is indexed by search engines like Google. Therefore, a slight keyword density can definitely improve your SEO efforts.

Experiment 2

Do we have new ways to fill the 100-character keyword field more effectively?

You may already know the basics to optimize your keyword field:

  • Separate keywords with a comma and do NOT use spaces
  • Do not include both singular and plural, especially for English keywords
  • Use all available characters

However, we wanted to show you a tweak we found while optimizing some of our apps to maximize the amount of rankings we could get from technically including only one keyword.

Therefore, we will take some keywords and, instead of separating them with a comma or writing them together, we will separate them with a dash.

  • We noticed that when we added one keyword separated with a dash to our title, we would also rank for the keyword written together, even if we did not include it anywhere written together. So we tried to reconstruct this scenario and changed our keyword set:

title: 7 minute workout
keyword field: wallsit

title: 7 minute work-out
keyword field: wall-sit, test-123, test-321

We wanted to see if we could rank for “wall-sit,” “wall sit,” and “wallsit” altogether.

This is what we measured:


As you can see, the rankings did change quite a bit.

The keywords that got separated with a dash like “wall-sit” lead the app to rank for keywords like “wall sit” as well as “wall-sit.” However, apparently your app will not rank for “wallsit” if you do not explicitly write it together or include it in your title. By including it in the app title, we did found out that you could rank for both versions.


By including one important keyword in the app title and separating it with a dash, you get the whole advantages of the App Store ranking algorithm. Use 2 words instead of one and combine each with one another without losing the ranking of the keyword written together.

For example, you will rank for “workout,” “work-out,” or “work out” and all kinds of combinations with the keywords “work” + “keyword in title/keyword field” or “out” + “keyword in title/keyword field.”

Experiment 3

Can you increase your keyword field from 100 to 200 characters?

You might have already heard that you can take advantage of the fact that the App Store ranks your keywords for multiple countries.

That way, you can increase the keywords your apps will be indexed for from 100 characters to 200.

One rumor we are particularly interested in is that you can use English keywords in the Spanish keyword field to increase the amount of English keywords you rank for. Then, not to lose the Spanish rankings, you can just put the Spanish keywords in the Mexican keyword field.

Let’s test this hypothesis

Step 1: We searched for rankings of Spanish keywords in the US App Store and found clear evidence that Spanish keywords do rank in the US.


Step 2: We filled some test keywords in the Mexican keyword field and put it to the test if they rank in the Spanish App Store.



Unfortunately, this does not work at all. The Spanish App Store just indexes Spanish and English (GB) keywords and not Mexican ones. If you want to get an in-depth insight, take a look at the new overview Apple provides in iTunes Connect when you click on the dropdown menu to view the country where your app is available.

Then, click on “Learn more about App Stores and Localization.


Also, make sure to check out the great overview by Moritz Daan, Growth Hacker at Phiture.

Experiment 4

Does Apple take into account keywords placement in the title?

We wanted to find out if the relevance of particular keywords in the title could be increased individually.

  • Does a shorter title improve the rankings of the keywords in the title?
  • Does the position of the keyword in the title influence the ranking?

To find out how important the length of the app title really is on the App Store, we changed our title from 83 characters to 34 characters and compared the rankings.

Here is what happened:



Besides losing ranking for 3 keywords (which we excluded to shorten the title), we did not increase our ranking at all.

Apparently, according to the graph, the rankings even declined a little bit.

But then, why do bigger brands appear to have short titles?

Like, for example, Waze (title length: 33 characters)


or Soundcloud (title length: 26 characters)


After testing and some consulting with other app experts, we reached a conclusion.

Big brands use a longer app title to emphasize their brand recognition and to improve their click-through-rate. The CTR gets higher the shorter your title is.

However, most App Store developers should definitely use up to 80 characters in their app title. Also, they include the most important keywords to maximize visibility, as their brands might not be so popular.

What about the position of the keywords? Might that be one factor to influence the ranking of one specific keyword?

To test this, we took our Spanish version and changed the title

7 minutos de ejercicio – entrenamiento diario con 12 ejercicios de impulsar su metabolismo by arise

entrenamiento diario – 7 Min de ejercicio”.

We tried to emphasize on the keyword entrenamiento diario.

Let’s take a look at the results:



Well, our results showed that our experiments to change the length of the app title, as well as the position of the keyword in the app title, did not make any real difference in the rankings of our app.

Even though you could optimize your click-through-rate (CTR) by positioning the most important keyword at the beginning, this might not have any impact on your keyword rankings.

Experiment 5

Does repeating a keyword in the app title & keyword field impact ranking?

The last aspect we want to explore is if you can strengthen the ranking from one keyword by adding it to both the keyword field and the title.

To test this, we simply added 3 keywords in the title as well as the keyword field of our French app version and measured the impact.

So, again, we placed the keywords “entraînement,” “metabolisme,” and “exercices” both in the app title and keyword field. Here’s what we found:



As some rumors claimed that this would be a proper method to increase your ranking, we had to test it out. Apparently, by taking a look at the graph above, nothing changed after we did.

At this stage, we would not recommend you to use your keywords for both the app title and the keyword field. It would be a waste of space. You should rather focus on keywords that can create a high number of combinations, resulting in multiple rankings for long-tail keywords.


The overall opinion is that the App Store algorithm has changed quite a lot and that it got more advanced. When taking a closer look at the impact, the changes were not dramatic at all. As we tried to trick the App Store, we found out that lots of these methods don’t actually work to improve the ranking of apps.

Keywords optimization still is one of the most important things to focus on in your ASO efforts, even if you cannot optimize keywords in your App Store description or strengthen your title.

We, therefore, recommend you to focus on what is working:

  • Use 100 instead of 200 characters for your keyword field or
  • Try using use dashes to separate your keywords instead of commas to improve your overall outcome
  • Make more experiments, as the App Store and the overall discipline of ASO evolve constantly.

To sum this up, we want to emphasize once more that we are aware that the Apple algorithm considers much more aspects than just the keyword data alone, so even if we made sure to exclude other factors (reviews, user acquisition, etc.), changes in the rankings could, of course, have different causes.

In fact, the main purpose of this post was to show what has or has not worked in our particular case. If you’ve experienced anything else, maybe from an angle we did not think about yet, we are looking forward to reading your comments.

What do you think of these experiments? Anything you want to share with us?

Maximilian Lehmann
Maximilian considers himself a life long learner and is very passionate about the App ecosystem. While sharing his insights and helping App Startups and businesses with their App Store Optimization over at ASO-Perform-Apps he is always searching for new ways to make great Apps more visible and gain them more exposure.