App Store Keywords for Reference Apps: Easy to Rank, Easy to Overrate

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

Five of the six rows are quiet. "Periodic table" has difficulty 0 in every storefront and a volume above 9 only in the US. A volume score of 3 appears whenever few apps return for the phrase, so a row of 3s means an almost empty result set, not a hidden market. "Dictionary" is the only phrase with a mean difficulty near 30 (29.7, and 60 in the US), and the only one with volume above 40 in several storefronts.

Two numbers go together. Names are literal (57% repeat the query, second only to Graphics & Design) and plain, with the lowest separator share in the study, tied with Utilities at 27%. And the ratings are tiny: the Japanese median is 5, and the US median is about 830. Many of the apps that appear are small, single-purpose or niche, and nobody has built a brand yet. Among US results, 28.3% were Education apps and 8.3% Utilities, so a language or study tool in these phrases meets Education competition, not just Reference apps. The mapping from phrase to category is approximate everywhere, and it is looser here.

1. Do not read zero as opportunity. Difficulty near 0 plus volume near 3 may describe a dead phrase. The guide on spotting dead keywords gives the checks, and keyword research for a niche app shows how to size a small market honestly.
2. Separate your anchor from your extras. If you build a dictionary, thesaurus or converter, those are the phrases with measurable demand (volume 22 to 46). Use cheaper phrases such as "encyclopedia" or "field guide" as secondary signals for a specific subject area, not as the plan.
3. Be literal. In a category where names are plain and short, an honest name that states the subject is normal. As with every correlation here, that does not prove that the name causes ranking.
4. Consider the other category. For books about a subject, look at Books; for small calculators and converters, see Utilities, where the unit-converter type of tool also lives and where the numbers are higher.

The study ran six generic English phrases per category through the iTunes Search API (entity=software, limit=25) in the US, GB, DE, JP, FR and BR and analysed the top 10 results: 936 queries, 36 for Reference, fetched 2026-11-01. Because phrases were English everywhere, the DE, JP, FR and BR columns show English demand only. See 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, each in its local language. It costs $29 one time; the free download needs a license key to run. See pricing.