Discover apps gaining traction in the US that haven't been localized or released in Japan yet. An information hub for indie developers hunting their next opportunity.
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Maker
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Hi PH! 👋 I'm an indie developer based in Japan.
I kept noticing the same thing: apps blowing up in the US App Store that simply don't exist in Japan yet — no localization, no release, nothing. Every one of those felt like an open opportunity just sitting there, but tracking them by hand was painful.
So I built ProductGapRadar. Every day it surfaces US apps gaining traction that haven't landed in Japan yet — a running list of market gaps for indie devs looking for their next thing to build.
I'd love to hear: if you're a builder, what's the last "why doesn't this exist here yet?" moment you had? And for anyone who's localized an app across markets — what worked, what didn't?
Happy to answer any questions 🙏
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How often does the data refresh, and is it pulling from app store rankings directly or some third-party source? Curious how reliable the traction signals actually are.
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Maker
@erginel28238 Daily via GitHub Actions cron. Source is Apple's own official RSS charts (US top-100 free/paid) cross-checked against the iTunes API for JP availability — no third-party estimate data.
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How often is the data refreshed, and what sources do you pull from to confirm an app is actually gaining traction rather than just getting a brief spike?
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Maker
@ezraksat5896 Daily (GitHub Actions cron). Sources: Apple's official RSS charts (US top-100 free/paid) for rank, cross-checked with the iTunes API for rating count/average. Right now it's a snapshot at time of detection — no multi-day sustained-rank tracking yet, so it can't distinguish a lasting trend from a brief spike. That's on the roadmap.
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How does it actually flag traction in the US though, just download rank jumps or something deeper like retention or revenue signals?
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Maker
@hamidetakntgk3 Right now it's just US App Store chart rank (top-100 free/paid) plus rating count/average from the iTunes API — no download-jump delta, no revenue or retention data. It's "currently ranking in the US" as the signal, not a deeper growth metric.
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How do you actually determine traction in the US market, like is it based on downloads, revenue, or some blend of metrics you track?
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Maker
@azizileskaxtxg It's based purely on US App Store chart rank (top-100 free/paid, from Apple's own RSS feed) — not downloads or revenue data, since Apple doesn't expose those publicly. Rating count/average from the iTunes API is the only secondary signal.
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How do you actually source the traction data, and is it updated daily or more like a weekly snapshot?
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Maker
@kumsaldanmkkvf Daily, via GitHub Actions cron. Source is Apple's official RSS charts (US top-100 free/paid) — chart rank is the traction signal, no third-party data.
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Finally a focused lens on the US-to-Japan gap. Scrolling through trending apps that skipped localization gave me three solid leads in under five minutes.
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Maker
@eymenevf2 Thank you! We plan to support multiple languages moving forward.
How often does the data refresh, and is it pulling from app store rankings directly or some third-party source? Curious how reliable the traction signals actually are.
@erginel28238 Daily via GitHub Actions cron. Source is Apple's own official RSS charts (US top-100 free/paid) cross-checked against the iTunes API for JP availability — no third-party estimate data.
How often is the data refreshed, and what sources do you pull from to confirm an app is actually gaining traction rather than just getting a brief spike?
@ezraksat5896 Daily (GitHub Actions cron). Sources: Apple's official RSS charts (US top-100 free/paid) for rank, cross-checked with the iTunes API for rating count/average. Right now it's a snapshot at time of detection — no multi-day sustained-rank tracking yet, so it can't distinguish a lasting trend from a brief spike. That's on the roadmap.
How does it actually flag traction in the US though, just download rank jumps or something deeper like retention or revenue signals?
@hamidetakntgk3 Right now it's just US App Store chart rank (top-100 free/paid) plus rating count/average from the iTunes API — no download-jump delta, no revenue or retention data. It's "currently ranking in the US" as the signal, not a deeper growth metric.
How do you actually determine traction in the US market, like is it based on downloads, revenue, or some blend of metrics you track?
@azizileskaxtxg It's based purely on US App Store chart rank (top-100 free/paid, from Apple's own RSS feed) — not downloads or revenue data, since Apple doesn't expose those publicly. Rating count/average from the iTunes API is the only secondary signal.
How do you actually source the traction data, and is it updated daily or more like a weekly snapshot?
@kumsaldanmkkvf Daily, via GitHub Actions cron. Source is Apple's official RSS charts (US top-100 free/paid) — chart rank is the traction signal, no third-party data.
Finally a focused lens on the US-to-Japan gap. Scrolling through trending apps that skipped localization gave me three solid leads in under five minutes.
@eymenevf2 Thank you! We plan to support multiple languages moving forward.