App Store Keywords for Books Apps: Readers, Audiobooks and Trackers

Estimated volume / estimated difficulty, 0-100, English phrases in every storefront.

Different kinds of reading product produce different curves. "Bible" and "audiobooks" are consumption terms with a few very large apps, and Brazil sits closer to the US than Germany or Japan for "bible" (73 / 53). "Comic reader" and "manga reader" are format terms: outside the US their difficulty is in single digits or low teens, yet their volume scores of 14 to 47 show real demand. "Book tracker" is a US-heavy utility phrase: 62 / 44 in the US, 9 / 0 in Japan.

Books is a smaller category by demand but a literal one by naming. Half of the top-10 names contain the whole phrase, and the typical name is a little more than a character shorter than the median. In the US, 75.0% of the results carry the Books genre (the API calls it "Book"); Entertainment accounts for 11.7% and Reference for 10.0%, which suits audio and bible-study tools. The phrase-to-category mapping is approximate across the study.

Storefront matters more than phrase for Books: the mean difficulty is 48.2 in the US and 8.0 in Japan, with Great Britain, Germany, France and Brazil at about 21 to 24. In short, Books is not a hard category outside the US.

• Format words are an opening. If your app handles a particular format (comics, manga, epub), the data says such terms are cheap and not empty. See long-tail App Store keywords for how to check whether a small phrase has real demand.
• Use literal names where they are honest. With half of the top-10 names repeating the phrase, a clear descriptive name is the norm here. Compare yours with the three or four apps that actually rank for your key phrase before copying the pattern; correlation is not cause.
• Use the secondary slot for the second audience. Apple indexes both the primary and the optional secondary category. A study aid might be Books or Education; a dictionary-like companion may sit better in Reference. The guide on choosing primary and secondary category gives the decision order.
• Remember the neighbour for periodicals. Magazine-style subscriptions belong with Magazines & Newspapers.

For each of 26 categories we queried the iTunes Search API (entity=software, limit=25) with six generic English phrases in the US, GB, DE, JP, FR and BR and analysed the top 10 results per query; Books accounts for 36 queries and 360 slots, fetched 2026-11-01. The details are in the research methodology, the research hub and how we measure. Data: category CSV.

LocalASO is a Mac app that estimates volume and difficulty in 52 storefronts, researching each storefront in its local language. It costs $29 one time; the download is free but the app needs a license key. See pricing.