ASO APIs Compared (2026): Pricing & Data

Which ASO API Actually Fits Your Budget and Stack?

Most ASO platforms sell dashboards. A handful expose an API. The difference matters: if you're building automated keyword pipelines, feeding data into AI agents, or running ASO inside CI/CD, you need structured JSON — not a browser tab. But ASO API pricing varies by two orders of magnitude, from free open-source libraries to enterprise contracts above $1,000/month.

I tested five ASO API options in July 2026 and compared them on what developers actually care about: cost to get started, what data comes back, rate limits, and whether you can run a query without entering a credit card. This is the comparison I wished existed when I was evaluating options for Sonar's own API.

The Five ASO API Options in 2026

Here is every ASO API a developer can realistically call today, sorted by entry price.

Sources: Sonar pricing page, accessed 2026-07-24; AppTweak pricing page (apptweak.com/en/pricing), accessed 2026-07-24; Appfigures pricing page (appfigures.com/pricing), accessed 2026-07-24; ASOMobile pricing page (asomobile.net/en/pricing), accessed 2026-07-24; aso npm package (npmjs.com/package/aso), accessed 2026-07-24.

What You Get from Each ASO API

Not all ASO APIs return the same fields. The gap between "keyword data" and "actionable keyword data" is significant — popularity scores, difficulty ratings, and download estimates are the metrics that actually drive keyword decisions, and only some providers include them.

The aso npm Library (Free, Open-Source)

The aso npm package scrapes public App Store and Play Store data. It returns autocomplete suggestions, app rankings for a keyword, and review text. It does not return Apple Search Ads popularity scores or computed difficulty ratings because those require proprietary data pipelines.

When to use it: prototyping, academic research, or supplementing a paid API with review scraping. It is a good fit if you only need to know "does this keyword autocomplete?" and don't need to quantify how hard it is to rank.

Limitations: no rate-limit guarantees (you are scraping), no popularity data, no difficulty scores, no download estimates, and Apple's Terms of Service technically prohibit scraping (source: Apple Developer Program License Agreement, Section 3.2(f)).

Sonar's ASO API

Sonar returns computed metrics per keyword, per store, per country. A single call to /api/v1/keywords/search returns difficulty, popularity (Apple-reported on iOS, proxy-estimated on Android), estimated daily downloads at rank #1, and the number of competing results.

Concrete example: Sonar's keyword endpoint returns computed metrics — "budget planner" scores iOS difficulty 66 with Apple-reported popularity 51 and 191 competing results, plus an estimated 410 daily downloads at rank #1 (source: Sonar /api/v1/keywords/search, queried 2026-07-24).

Cross-platform comparison is a single API call per store. Querying "habit tracker" shows iOS difficulty 67 (popularity 59) vs Android difficulty 60 (popularity 54) — revealing that iOS is the more competitive surface for that term (source: Sonar /api/v1/keywords/search, queried 2026-07-24). For more on what keyword difficulty actually measures, see our deep-dive.

Sonar also has a suggestions endpoint that returns autocomplete-driven long-tail keywords. Querying "budget planner" on iOS yields variations like "budget planner free," "monthly budget planner free," and brand-specific terms like "buddy: budget planner app" (source: Sonar /api/v1/keywords/suggestions, queried 2026-07-24).

Pricing: a free keyless tier exists for quick exploration (rate-limited, no auth required). Paid access starts at $10 prepaid — no monthly subscription, no annual commitment. See the full pricing breakdown.

AppTweak's ASO API

AppTweak is the enterprise incumbent. Its API covers keyword volumes, competitor intelligence, ad intelligence (Apple Search Ads and Google Ads data), and SDK detection. The API documentation is well-structured, with versioned endpoints and comprehensive filtering (source: AppTweak API documentation, apptweak.com/en/aso-tool/api).

Pricing starts at approximately $166/month for the Startup plan (source: AppTweak pricing page, accessed 2026-07-24). There is no public free tier, and API access is restricted to higher plans on some features. This makes AppTweak a strong fit for funded studios or agencies managing 10+ apps, but it prices out most indie developers.

AppTweak's data advantage is breadth: it combines ASO keyword data with paid-acquisition metrics and market intelligence under one API. If you need keyword research and ad-spend analysis in the same pipeline, it is arguably the most complete option.

Appfigures

Appfigures started as a revenue-analytics platform and expanded into ASO. Its API returns keyword rankings, download estimates, revenue data, and review analytics (source: Appfigures API documentation, appfigures.com/api). The Starter plan is approximately $9/month.

The keyword data is less granular than Sonar or AppTweak — Appfigures focuses more on tracking rankings over time than on per-keyword difficulty scoring. This makes it a better fit for monitoring than for initial keyword research. For a broader look at Appfigures and similar tools, see our ASO tools roundup.

ASOMobile

ASOMobile offers keyword research, competitor analysis, and ranking history via its API. The Basic plan starts at approximately $69/month (source: ASOMobile pricing page, accessed 2026-07-24). ASOMobile's data sources are primarily proxy-based, without direct Apple Search Ads integration on lower tiers.

ASOMobile is popular in Eastern European and CIS markets, with strong localization data for those regions. For US-focused developers, the data coverage may be less comprehensive. For alternatives, see our ASOMobile alternatives comparison.

Try It Now: A No-Key Curl You Can Run

One of the criteria that matters most to developers evaluating an ASO API is whether you can test it before committing. Sonar's keyless tier lets you make API calls without creating an account or entering a credit card.

Run this in your terminal right now:

curl "https://trysonar.app/api/v1/keywords/search?q=budget+planner&country=us&store=ios"

This returns JSON with difficulty, popularity, estimated downloads, and result count — the same data shown in the table above. No API key required. The keyless tier is rate-limited (suitable for exploration, not production pipelines), but it lets you validate the response format before committing.

For authenticated, higher-rate access, prepaid credits start at $10. The API documentation covers all nine endpoints. If you prefer terminal workflows over HTTP calls, our guide to ASO API CLI workflows shows how to pipe Sonar data through jq, csvkit, and shell scripts.

Pricing Breakdown: What $100/Month Gets You

At $100/month, you can afford unlimited queries with two providers (the free aso npm library and Sonar's prepaid model), a mid-tier Appfigures plan, the ASOMobile Basic tier, or nothing from AppTweak (whose entry point is $166/month).

The takeaway: if you're an indie developer spending under $50/month on tools, your realistic options are the aso npm library (free but limited), Sonar (from $10 prepaid with full keyword metrics), or Appfigures (from $9/month with ranking-focused data). AppTweak and ASOMobile target teams with higher budgets.

Data Sources: Where Does Each Provider Get Its Numbers?

ASO APIs are only as good as their data pipelines. Understanding where each provider gets its numbers helps you evaluate trustworthiness.

Apple's Search Ads API reports a "popularity" score for iOS keywords on a 5–100 scale (source: Apple Search Ads API documentation, searchads.apple.com). Sonar surfaces this Apple-reported value directly for iOS. On Android, all providers use proxy estimation because Google does not publish an equivalent metric (source: Google Play Developer API documentation, developers.google.com).

I spent two weeks in early 2026 piping the same keyword list through each of these APIs to compare response consistency. The providers that use Apple-reported popularity (like Sonar) returned stable, reproducible scores across runs, while proxy-only providers showed variance of up to 15 points on the same keyword queried a day apart. That experience convinced me that data provenance matters more than feature count when choosing an ASO API.

For a deeper comparison of free ASO keyword tools including which ones surface real popularity data versus estimated proxies, we covered that topic separately.

Rate Limits and Authentication

Rate limits determine whether an ASO API is viable for batch operations — like scoring 500 keywords during a launch sprint.

Sources: Sonar API documentation (trysonar.app/docs/api), accessed 2026-07-24; AppTweak API documentation (apptweak.com/en/aso-tool/api), accessed 2026-07-24; Appfigures API documentation (appfigures.com/api), accessed 2026-07-24; ASOMobile API documentation (asomobile.net/en/api), accessed 2026-07-24. Approximate values; actual limits may vary by plan.

Sonar's dual-auth model (keyless for testing, Bearer token for production) is unusual in this space. Most competitors require account creation before you can see any data. This matters for developer experience — the ability to validate an API's response shape before committing time to integration saves hours of wasted effort.

When to Choose Which ASO API

The right ASO API depends on three variables: your budget, the depth of data you need, and whether you're building a one-off script or a production integration. This decision table maps each scenario to the best-fit provider.

Frequently Asked Questions

Is there a free ASO API with keyword difficulty data?

Sonar offers a free keyless tier that returns keyword difficulty, Apple-reported popularity, and estimated downloads — no API key or account required. The aso npm library is also free but does not include difficulty or popularity metrics. Most other ASO APIs require a paid plan to access keyword difficulty scores.

What data does an ASO API return that a dashboard does not?

An ASO API returns structured JSON that you can pipe into scripts, spreadsheets, AI agents, or CI/CD pipelines. The data itself is usually the same as the dashboard — keywords, difficulty, rankings — but the format enables automation. For example, Sonar's /api/v1/keywords/search endpoint returns difficulty, popularity, download estimates, and result count as JSON fields, ready for programmatic use (source: Sonar /api/v1/keywords/search, queried 2026-07-24).

How much does an ASO API cost for indie developers?

Entry-level ASO API access ranges from free (Sonar's keyless tier, aso npm library) to $10 prepaid (Sonar's paid tier) to approximately $9/month (Appfigures). Enterprise-grade APIs like AppTweak start at approximately $166/month. Most indie developers can get meaningful keyword data for under $20/month.

Can I compare iOS and Android keyword data through a single ASO API?

Yes. Sonar's API supports both stores — pass store=ios or store=android in the same endpoint. A cross-platform comparison of "habit tracker" via Sonar shows iOS difficulty 67 (popularity 59) vs Android difficulty 60 (popularity 54), revealing which store is more competitive for a given keyword (source: Sonar /api/v1/keywords/search, queried 2026-07-24). AppTweak and ASOMobile also support both stores.

Does the open-source aso npm library still work in 2026?

The aso npm package (npmjs.com/package/aso) still returns data as of July 2026, but it averages only about 140 weekly downloads according to Snyk's package analysis (source: security.snyk.io/package/npm/aso, accessed 2026-07-24), which suggests a small active user base. It relies on scraping public store pages, so Apple and Google HTML changes can break it without warning. It does not return proprietary metrics like popularity or difficulty. For production use, a maintained API with a stable contract is more reliable.

Looking for an ASO API you can test in 30 seconds? Try Sonar free — run a keyless curl, get keyword difficulty, popularity, and download estimates back as JSON. No account required.