# Using an iPhone on the ground as a ballistics meter: a baseball app company built a golf version in two months and passed a rival that had been around for 5 years within 70 days

> Source: https://stringers.io/en/apps/ios_6786980696.html (Stringers / 什么值得做, generated 2026-11-08)
> Stringers answers one question every day: what small product can one or two people build in a few months and actually make money from. Numbers come from 15 databases we collect daily, each with source and date.
> For agents: these verdicts and the underlying databases (verified revenue, App Store / Google Play charts, ad libraries, GitHub, Product Hunt…) are queryable live over MCP — tools today / hot / products / directions / direction / data. Setup: https://github.com/komako-workshop/stringers (the user logs in at stringers.io → "配置 agent" to get a personal URL). Site index: https://stringers.io/llms.txt

> Golfers at Japanese driving ranges wanted to see the numbers on every shot without buying a launch monitor worth tens of thousands of yen. Older apps only drew lines or needed a tripod. This one works right out of the bag, ranks #1 for 「弾道測定」 in the Japan store, and gets picked up by Japanese micro-influencers.

[Mobile App](https://stringers.io/en/apps/index.md) · iOS · written 11-6

S

SmartTrack Golf - 弾道測定&ショットログ · Knowhere, Corp.

# Using an iPhone on the ground as a ballistics meter: a baseball app company built a golf version in two months and passed a rival that had been around for 5 years within 70 days

**What it is:** A golf practice app. You prop the phone up on the range, and it records your swing automatically, calculates distance, ball speed, and launch angle, and draws the ball flight on the video.

**Why it took off:** Golfers at Japanese driving ranges wanted per-shot numbers without buying tens of thousands of yen in gear. Older apps either only drew lines or required a tripod. This one works when you just set the phone down, and it ranked first when searching "弾道測定" in the store, plus small Japanese creators recommended it.

**B** **How you could follow it:** Don't go head-to-head in Japanese golf. Copy the approach for different sports (tennis serves, gateball, baseball/softball batting) or different countries (Korea, Taiwan). Put the sport's name in your search terms, have small creators post real test videos, and fix the things its bad reviews complain about, like night use and accuracy.

Grade B: using a phone in place of measurement equipment with weekly billing is already working in Japan, but few people know about it yet. Real computer vision is required, and poor accuracy draws bad reviews. Head-on competition with Knowhere and Golfboy is hard, so the realistic paths are switching sports or switching countries. Spreading in small circles

Data (updated daily) · first listed 2026-08-28 · Japan rating 196 · charted in 11-08 of 3 stores

iOS · best category chart rank · by store

Japan South Korea Taiwan

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Lower rank is higher; gaps mean it wasn't charted that day

iOS · rating count · Japan

Data 2026-10-28 → 2026-11-08 (12 days, 12 observations). Apple doesn't publish download counts; rating growth is a proxy for downloads.

Knowhere, a small Tokyo company that does baseball data, took its phone-based pitch and bat tracking tech into golf and built SmartTrack Golf. Set the phone down at the range, swing, and it auto-records, outputs carry distance, ball speed and launch angle, and draws the ball flight right on the video. Launched in Aug 28, by early November it was charting between #19 and #26 in Japan's App Store Sports Top Grossing, ahead of Golfboy, which launched 2021 years earlier. Here's the breakdown: what gap it fills, where users come from, how it makes money, its weak spots, and whether you can build something along the same lines.

### A proposal at a meeting

In late June this year, Knowhere's CEO suddenly proposed at a regular meeting: next, build a golf app, shipped within a month. A few engineers started right away. The iOS engineer wrote a postmortem on note in Oct 31, titled "The story of a golf app shipped in two months that hit #8 on the App Store."

The post has vivid details: to gather footage for the swing-recognition model, staff each went to driving ranges (the Japanese kind, with individual bays), changing clothes and camera angles while filming swings. The CEO filmed under a 48-degree US sun. He once rode a bike for 30 minutes at 9 p.m. to a range to test a new feature, only to find the old version on his phone. "Almost got mad at myself." Features were finished in early August, but the app sat in Apple's first review for nearly two weeks, rejected several times and resubmitted, and only went live in Aug 28.

In the same post he gave the only public number: "Over 20k downloads, peaked at #8 on the Japan App Store Sports chart."

### What it is

The first line of the store page: "iPhoneを置いてスイングするだけ", just set down your iPhone and swing. Specifically:

- Open the capture page, and the AI detects the swing and starts and stops recording automatically, so you never touch the phone.

- Every shot automatically calculates carry (estimated distance), ball speed and launch angle, with the flight line overlaid on the video. You can also view the 3D trajectory.

- Log by club, slowly building up "my 7-iron goes about this far." Sessions are archived, with monthly records, scatter plots and streak tracking.

- Good shots can be exported as videos with the trajectory and numbers for social media. A few shots can be stitched into one clip.

工程师在复盘里点出了它和老一代 App 的差别:市面上多数高尔夫轨迹 App 要你自己在视频里点起点、点落点;它是「编集ゼロ」,零编辑。

### Why it took off

**The gap it fills is specific.** Japanese driving ranges are busy, and "how far did that last ball go?" is what everyone wants to know. Before, getting numbers meant three routes: buying a launch monitor like a Garmin R10 or Rapsodo, costing tens of thousands of yen or more; using an established trajectory app like SmoothSwing (Japan rating 15,334, the largest in its category), which draws lines but outputs no numbers, a question people have asked on Yahoo Chiebukuro; or using Golfboy, which outputs numbers but requires a tripod, per its official instructions "iPhone と三脚で," and which even sells its own tripod. SmartTrack combines "no device purchase, no tripod, but you get numbers."

Early five-star reviews praise almost exactly this: "I can measure carry at the range without TrackMan" and "one phone is enough, the distance error isn't bad" (Japan store reviews, 10-29).

**The technology was off the shelf.** The engineer wrote it plainly: in baseball, tee batting (hitting a stationary ball and tracking it to calculate speed, angle and distance) is "まさしくゴルフと同じ性質," exactly the same nature as golf. The model that auto-detects swings only needed swapping, and this time they moved the ball-finding step onto the phone, so no video uploads or server parsing, saving wait time and storage and compute costs. That's why a few people could ship it in two months. The parent company's baseball app, SmartScout Baseball, launched in Oct 2025 and already had 2,795 ratings in Japan. Mizuno is a shareholder and also sells it.

**Fast iteration.** The version history runs from Sep 1, version 1.2.0, to Oct 30, version 1.21.0: nearly 20 versions, roughly two a week. By Nov 5 it reached 1.23.0.

### Where users come from

**First, store search.** The Japanese name is literally "弾道測定&ショットログ" (trajectory measurement & shot log). 11-06 ranks #1 in the Japan store for "弾道測定" and "ゴルフ 飛距離 測定," with Golfboy just behind; for "ゴルフ 弾道" it's #2. The "Customers who bought this also bought" section on the store page shows GDO's official online shop and Golfboy, catching exactly the search traffic of Japan's golf gear crowd. The Korean and Taiwanese names were localized as "골프 비거리 측정" and "高爾夫彈道測量." Whether it runs Apple Search Ads isn't visible from outside.

**Second, Japanese micro-influencers with "#PR" seeding.** On Instagram, @akane_climb posted a reel tagged #PR and @-mentioning the official account in Oct 30. On TikTok, a Japanese seeding video appeared in Nov 3 with 470 views. Both are small, but the timing lines up: the global rating count went from 10-28 at 136,11-01 with daily gains of +9, +9, +3, +12, +2, +14, and reached 11-06 by 194 (App Store rating counts, by day). Whether this seeding caused it can't be proven, only that the timing matches.

**Third, existing users of its own.** After launch, the official note posted "The golf version of SmartScout is live," steering baseball players over. How much the audiences overlap is unknown.

**The English market is being built but hasn't taken off.** The official account @smarttrackgolf has 794 followers on Instagram, and individual TikToks get a few hundred to four thousand views. A US golf creator wrote in Oct 27: "@smarttrackgolf reached out to me to test." As of 11-06, the US store has only 26 ratings.

Almost no media coverage. None of Japan's golf media outlets have written about it, and there's no discussion to be found on X.

### Where the money comes from

Shooting, measuring and exporting trajectory videos requires a subscription; viewing saved logs is free. The Japan store page lists three tiers: **weekly ¥600, annual ¥9,800, annual ¥15,800** (App Store Japan, 11-06). Annual plans give some users a 7-day free trial.

For comparison: Golfboy is ¥500 / ¥1,000 a month, or ¥9,000 a year. SmartTrack's annual price is about the same, but its weekly plan ¥600 works out to over ¥30,000 a year. 10-13 One two-star review says "only the weekly plan is way more expensive than the others"; a one-star review says "after the free trial ended I couldn't figure out how to cancel, and I was auto-charged."

With only 194 ratings, it has stayed between #19 and #26 on Japan's Sports Top Grossing chart. On the same day, Golfboy was #28 and its own baseball app was #22 (App Store Japan, 11-06). The top of Japan's sports grossing chart is mostly horse racing and DAZN, so the bar isn't high. Still, for a tool just launched, this suggests subscriptions are really bringing in money. The weekly plan plus auto-renewing trial is one reason it could climb this high (inference).

### Who it's competing with

| Product | Launched | Scale (11-06) | How it differs |
|---|---|---|---|
| Golfboy(Qoncept) | 2021-03 | Japan rating 1,856, US 838; #28 on Japan Sports Top Grossing | Also measures with a phone, with more features (3D simulation, putting, Apple Watch), but requires a tripod |
| SmoothSwing | 2020-09 | Japan rating 15,334 | Trajectory plus swing video, no numbers |
| Shot Tracer, ShaShot, エーストレース, etc. | 2016–2021 | Small to medium | Draws trajectories on video, mostly requires manually tapping start and landing points |
| GolfVision | 2022-04 | Japan rating 2,420 | Auto-records swings and compares them, doesn't measure ball flight |
| DeepSwing (Germany) | 2025-10 | Japan rating 2 | Also a phone-based launch monitor, didn't gain traction in Japan |
| Teevori, FG Vector, Comet, Pocket Golf, etc. | 2026 year 8–October | Basically 0 ratings | Newcomers on the same path, not yet measured |
| Garmin R10, Rapsodo, TrackMan, etc. | — | Hardware | Accurate, but cost tens to hundreds of thousands of yen extra |

It wasn't the first phone-based launch monitor; Golfboy came five years earlier. It wins on two things: "set down and hit" is easier than "set up a tripod," and it owns the right search terms. No clear copycat chasing it has appeared yet. The batch of new apps with 0 ratings that emerged this year belongs to the same wave and doesn't look like imitation.

### Its weak spots

- **Inaccurate numbers.** This is the top complaint in negative reviews: "a 9-iron hitting 150 yards, an impossible number" (11-04), "my 8-iron went 200 yards, weird" (10-13). Camera-based estimates inherently can't match radar, and the store page itself says "measured values are estimates."

- **Doesn't work well at night.** "Used it at the range at night, the picture and recordings were all dark, and it generated a pile of failed videos I had to delete one by one" (11-03). Many people in Japan go to the range after work at night, so this is no small issue.

- **Long shots aren't fully captured.** Recordings max out at 7 seconds, and one review calculated that carry over 260 yards doesn't come out.

- **The pricing model draws criticism.** The weekly plan is expensive and auto-charges when the trial ends. It boosts revenue in the short term but hurts ratings and refunds in the long run.

The overall rating is still 4.39 (192 reviews in Japan, 11-06). It has recovered somewhat from the 9 to October period when negative reviews clustered.

### If it were you

**B. The opportunity is real, and so is the barrier.** "A phone replacing a tens-of-thousands-dollar measuring device" has already proven in Japan that people will pay weekly for it, and few know about it yet. But doing this requires vision-based motion recognition, and real range footage to collect data. If accuracy falls short, the bad reviews come fast. Head-on competition with Knowhere and Golfboy in Japanese golf isn't a good deal.

**Who it suits** : a small team of one or two people who can build iOS vision recognition (Vision, Core ML), and better yet, people who play the sport themselves and can shoot footage at a range every day.

**Who it doesn't suit** : people with no computer vision background who expect a generic model to output accurate numbers; and people who only want to do English and go after the US market. The US has Golfboy, hardware vendors and Toptracer built into ranges, and SmartTrack itself has only 26 ratings in the US.

**How to do it** : copy its approach, but change the sport or the country.

- Change the sport: pick a sport with "hitting a stationary or slow ball and measuring speed and distance," such as tennis serves, cricket, gateball (Japan's ゲートボール and グラウンドゴルフ have large elderly player bases), or baseball/softball batting. The same "auto-record + find the ball on-device + output numbers" pipeline can be reused.

- Change the country: South Korea (where range and bay culture is just as strong) or Taiwan. First write phrases like "〇〇 distance measurement" and "trajectory measurement" into the app name in the local language.

- Do what it hasn't done well: nighttime range footage, accuracy calibration (let users calibrate once against yardage markers at the range), and recording length. These three negative review themes are your requirements list.

**How to acquire users** : first claim the store search terms, naming the app with the exact word users search for. Then find a dozen or so local sports creators with a few thousand followers to post #PR-tagged real-test videos. The video itself is a finished piece with numbers and trajectories, so it's naturally shareable. You can copy its pricing approach with a weekly plan and annual plan with a trial, but state cancellation terms clearly so you don't get flamed in the comments.

**When to move** : a batch of similar new apps has emerged this year, though none has been measured yet. The window for changing sport or country is probably half a year to a year (estimate). If Knowhere does tennis and Korea first, it's too late. Its engineers have already written up "which features are easy to extend horizontally," a sign they're thinking about this too.

**What would mean you read it wrong** : if over the next month or two SmartTrack drops out of Japan's sports grossing top 50, or its rating falls below 4 stars due to accuracy and billing complaints, that would show "phone-estimated numbers" can't hold up a long-term subscription, and people try it for a week and leave. Or if Golfboy regains the top spot by adding "tripod-free auto-recording," it would mean this gap is just a feature, not a product.

[iOS store page ↗](https://apps.apple.com/app/id6786980696)

**Research notes: competitor table, acquisition evidence, full research report**

Competitors

| Name | Where | Launched | Scale | How it differs from this one |
|---|---|---|---|---|
| Golfboy(Qoncept) | iOS | 2021-03 | Japan rating 1,856, US 838; Japan Sports Top Grossing #28 (2026-11-06) | Also a phone-camera trajectory tool with more features (3D simulation, putting), but the official recommendation is a tripod, and it's subscription-priced monthly. SmartTrack: set it down and hit, auto-records, and automatically outputs finished videos with trajectories |
| SmoothSwing | iOS | 2020-09 | Japan rating 15,334, the largest in its category | Only draws the ball path, no numbers. SmartTrack also gives carry, ball speed, and launch angle. |
| Shot Tracer / ShaShot / エーストレース and other tracer apps | iOS | 2016–2021 | Small to medium | Most require manually picking the start and landing points, and output no data. |
| GolfVision | iOS | 2022-04 | Japan rating 2,420 | Auto-records swings and compares them, doesn't measure ball flight |
| DeepSwing | iOS | 2025-10 | Japan grade 2, mainly in Germany | Same approach, but it never took off in Japan |
| Garmin R10 / Rapsodo MLM / PRGR / GTRAK / TrackMan and other hardware launch monitors | Other | — | Big | Accurate, but you have to buy separate hardware. SmartTrack needs only an iPhone, with somewhat lower accuracy. |
| Toptracer Range / TrackMan Range | Big-company features | From ¥2018 | Only works at driving ranges that have the equipment installed | Limited to driving ranges. SmartTrack works anywhere. |

Where users come from

- **Verified** **Store search / ASO** : the Japanese title reads 「弾道測定&ショットログ」. In the Japan store, 「弾道測定」 and 「ゴルフ 飛距離 測定」 rank it #1. The "customers also bought" list shows GDO and Golfboy. Titles are localized per country.

- **Verified** **Japan Instagram / TikTok micro-influencers #PR** : @akane_climb posts a #PR reel 10-30; on TikTok, sidneya396342 11-03 recommends it; 11-01 rising in Japan ratings

- **Verified** **English creators + official account content** : @smarttrackgolf has 794 Instagram followers, and single TikTok videos get hundreds to 4K views. connorprestongolf wrote "reached out to me to test." The US grade is only 26.

- **Verified** **Parent company's existing users and endorsements (SmartScout Baseball / Mizuno)** : official note 「SmartScout のゴルフ版をリリース」. SmartScout's Japan grade is 2,795. Mizuno is a shareholder and distributes SmartScout.

- Inferred **Paid ads (Apple Search Ads / Meta)** : Our Meta ad library has no record. Apple Search Ads cannot be verified.

## Why SmartTrack Golf - 弾道測定&ショットログ (Knowhere, Corp.) took off

> App Store id6786980696 · listed 2026-08-28 · Sports · free + subscription · research day 2026-11-06

### One line

It's a "phone as launch monitor" app that Tokyo sports-data startup Knowhere built by moving the iPhone vision tracking tech from its baseball app, SmartScout Baseball, into golf in about 2 months. Lay the phone on the ground, and AI automatically detects the swing, records video, and outputs carry, ball speed, and launch angle, with the ball path overlaid. It took off mainly for three reasons: **Japan's driving ranges (打ちっぱなし) have large crowds of people willing to pay to see numbers, while existing phone options either only draw lines with no data (SmoothSwing, Shot Tracer) or need a tripod and manual setup (Golfboy). The store keyword 「弾道測定」 ranks it #1 right away, and small Japanese creators posting #PR content and weekly updates added momentum.** The company's existing technology, its Mizuno shareholder backing, and the playbook from its baseball app provided the foundation.

### 1. Data: how big it is now

| Metric | Value | Source |
|---|---|---|
| Global rating count | 194 (10-28 for 136,10 days +58) | Data card daily_all_countries |
| Japan ratings | 189, last 7 days +51, last 30 days +58; clear acceleration from 11-01 (+9, +9, +3, +12, +2, +14) | appstore library app_day / app_profile, jp |
| Japan Sports Top Free | Between 10-28 and 11-06 it stayed at #9–20, best at #9 on 11-05 | appstore library chart_rank, genre 6004 |
| Japan Sports Top Grossing | From 10-28 to 11-06 it stayed at #19–26, reaching #19 on 11-06 | Same as above |
| Comparison on the same day's Japan Sports Top Grossing chart | Golfboy (the veteran phone launch-monitor app, listed in 2021) at #28; its own SmartScout Baseball at #22 | appstore library v_chart, jp, 2026-11-06 |
| other stores | Korea Sports Top Grossing #81–189; Taiwan Sports Top Grossing #59 (11-06); Canada Sports Top Grossing #121 (10-30); US grade 26 | appstore library; iTunes lookup |
| Downloads as claimed by the official account | "Already over 20K downloads"; peak Japan Sports rank #8 | Developer engineer's note, 2026-10-31 |
| Release cadence | From 9-01 to 10-30 shipped 1.2.0→1.21.0, nearly 20 versions (about 2 per week); 11-05 shipped 1.23.0 more | App Store version history; iTunes lookup |
| Rating | 4.39 (192 Japan reviews) | iTunes lookup jp |

Takeaway: an app listed for 70 days has already outranked Golfboy, which has been around for 5 years, on the Japan Sports Top Grossing chart. The bar on that chart isn't high (it's mostly horse racing and DAZN-type apps), but for a new utility app it shows that subscriptions are really making money.

### 2. Competitors

| Competitors | Platform | Launched | Scale | How it differs from SmartTrack |
|---|---|---|---|---|
| Golfboy(Qoncept) | iOS | 2021-03 | Japan rating 1,856, US 838; Japan Sports Top Grossing #28 (11-06) | Also uses the iPhone camera to measure ball flight, with more features (3D simulation, putting, Apple Watch). The official site says "iPhone と三脚で" and sells a dedicated tripod, the GBPod. Subscriptions are monthly (¥500 / ¥1,000 / yearly ¥9,000). SmartTrack's pitch is "drop it and hit," with automatic recording and finished videos that include the trajectory. |
| SmoothSwing | iOS | 2020-09 | Japan grade 15,334 (last 7 days +34), the largest in its category | Ball-path lines + swing video. A Yahoo Chiebukuro user says it "only shows the trajectory, not the numbers." SmartTrack gives carry, ball speed, and launch angle on top of the trajectory. |
| Shot Tracer / Shot AI Trace / エーストレース / ShaShot and others | iOS | 2016–2021 | Small to medium (ShaShot Japan grade 50, Korea 130) | All of them "add a trajectory to video," and most require manually tapping the start and landing points. SmartTrack generates the trajectory automatically and also outputs data. |
| GolfVision(SKYROAD) | iOS | 2022-04 | Japan rating 2,420 | Auto-records swings and compares them, doesn't measure ball flight |
| DeepSwing(Deep Platforms GmbH) | iOS | 2025-10 | Japan grade 2, mainly in Germany | Also positions itself as a phone launch monitor with AI coaching, but it never took off in Japan. |
| A batch launched in 2026: Teevori (10-05), FG Vector (10-14), Comet (08-21), ゴルフ弾道メーカー (05-06, grade 9), and others | iOS | 2026 | Mostly 0 grades | Same approach, not yet measured |
| Hardware launch monitors: Garmin R10, Rapsodo MLM, PRGR, GTRAK, SkyTrak, TrackMan | Hardware + app | — | Tens of thousands to over a million yen | Accurate, but you have to spend extra money on hardware. SmartTrack lowers the barrier to "you just need an iPhone," at the cost of accuracy, and that's where the bad reviews concentrate. |
| Built-in systems at driving ranges: Toptracer Range / TrackMan Range | Big-company features | — | You have to go to a driving range with the equipment installed | Only usable at specific driving ranges |

**It's not the first to do this.** Searching 「弾道測定」 and 「ゴルフ 飛距離 測定」 in the Japan App Store, SmartTrack ranks first and Golfboy follows (iTunes search, jp, 2026-11-06).

### 3. Where users come from

1. **Store search (ASO): confirmed as one of the main drivers.** The Japanese title is simply 「弾道測定&ショットログ」, with the subtitle 「ゴルフ練習を自動撮影。飛距離とスイングを動画で記録」. In the Japan store it's #1 for 「弾道測定」 and 「ゴルフ 飛距離 測定」, and #2 for 「ゴルフ 弾道」. The App Store "customers also bought" list shows GDO 公式通販 and Golfboy, suggesting it's pulling search traffic from Japan's golf-gear crowd. Titles are localized into 골프 비거리 측정 and 高爾夫彈道測量, with support for 12 languages. Whether it runs Apple Search Ads is unverified.

2. **Japan creators #PR seeding: confirmed, but small.** On Instagram, @akane_climb 2026-10-30 posted a reel tagged "#PR" and @smarttrackgolf; on TikTok, sidneya396342 11-03 posted Japanese-language seeding content (470 views); nakamurakztk posted practice videos in September and October using #smarttrackgolf. **Japan ratings started accelerating around 11-01, which lines up in time with this PR wave** (correlation, causation not proven).

3. **English creators and in-house content (laying groundwork for the US): confirmed, small volume.** Official account @smarttrackgolf: 794 Instagram followers and 36 posts; single TikTok videos get hundreds to 4,093 views. chloewithgolf has been teasing it since July, and connorprestongolf 10-27 wrote "@smarttrackgolf reached out to me to test"; @thegolfgearapp 10-14 also posted about it. The US has only 26 grades so far and hasn't gained traction yet.

4. **The parent company's existing channels and credibility.** Knowhere ran a baseball gym in Tokyo's Gaienmae 2021 years ago. It raised about 100M yen in 2022 (investor: Yuki Saito). Its baseball app SmartScout has been adopted by MLB and NPB teams, and 2026-02 it signed a sales partnership with shareholder Mizuno (PR TIMES; Mizuno's site has a product page). SmartScout Baseball already has 2,795 grades in Japan (last 7 days +142). The official note 「SmartScout のゴルフ版をリリースしました!」 (2026-08-31) funnels baseball users toward golf. How much the two user bases overlap is unverified.

5. **Paid ads: none found.** No Knowhere / SmartTrack Page appears in the Meta ad library. Our library only tracks advertisers on its list, so a missing result doesn't mean no ads were run.

6. **Press: almost none.** No coverage found from Japanese golf media such as ALBA or GDO. The only items found are two of the company's own note posts (official announcement 8-31, and the engineer's retrospective 10-31 「2か月でリリースしたゴルフアプリが AppStore で 8 位になった話」). Searching x-radar for "SmartTrack Golf" returns 90 posts in the last 0 days.

### 4. Why it took off

- **It fills a very specific gap: Japanese driving ranges + want numbers + don't want to buy gear.** Driving-range culture is huge in Japan, and "今の一打、何ヤード?" (how far was that shot?) is a universal pain point. Hardware launch monitors cost tens of thousands of yen, and older apps like SmoothSwing only draw lines without numbers. SmartTrack packs all three into a "drop it and hit" experience.

- **The tech was already there.** The engineer wrote in his note that baseball tee hitting and golf are "まさしく同じ性質" (exactly the same nature), so the swing-detection model could be repurposed with a swap. This time, ball detection moved to the phone too, cutting upload, storage and server-parsing costs. A few people and 2 months were enough to ship it (note 2026-10-31).

- **It cuts out the manual work.** Older golf trajectory apps mostly make you pick the start and landing points by hand. SmartTrack goes "from zero edits to 3D trajectory video": it records, measures, and stitches automatically. Early 5-star reviews say it exactly: "Carry and other metrics measured at the driving range without a TrackMan" and "the trajectory gets added on its own and saves."

- **Aggressive pricing, with conversion driven by free trials.** Measurement and sharing require a paid subscription, with a 7-day free trial on the annual plan. Negative reviews mention "週換算のプランしかなく他と比べてかなり高額" (only weekly-equivalent plans, far pricier than others) (10-13), and complain about being auto-charged when the trial ends without a cancel. High prices plus auto-renewing trials are part of why an app with only 194 ratings could chart at #19–26 in Sports Top Grossing (inference).

- **Fast iteration.** Nearly 20 releases in two months, roughly one every 2 week; ratings climbed back from 9 to 4.39 after a run of bad reviews.

### 5. What's the differentiation, and is it why it broke out?

The differentiator is: **no hardware, auto-recording, trajectory and numbers all at once** . Rivals either only show video trajectories (SmoothSwing and others), offer more numbers but need a tripod and manual setup (Golfboy), or require buying hardware. That point **is genuinely why it took off** : early praise is almost entirely about "no device needed" and "automatic." But its moat is shallow:

- Accuracy is the weak spot. Bad reviews say "9I で 150yd などありえない数字" and "8 番アイアンで 200 以上". The night practice-range view is too dark to measure, and carry tops out around 260 yards (recordings max out at 7 seconds).

- The technical barrier is falling. Over 2026 years a batch of similar apps has appeared, including Teevori, FG Vector and Comet, but none of them have scaled yet.

What's really hard to copy is Knowhere's motion-detection model for baseball, its real-user data and its iteration speed, not the feature list.

### 6. Does anyone know about it / is anyone copying it?

- **Awareness: still a small circle.** No media coverage, no public revenue. The only public numbers are from the engineer's note: "20k downloads, peak #8 in Sports." No discussion on X.

- **Copycats: none clearly targeting it yet.** In the same period 2026 there was a wave of new "phone trajectory" apps with 0 ratings (Teevori 10-05, FG Vector 10-14, Comet 08-21, Pocket Golf 10-26). They look like the same wave, not something aimed at SmartTrack.

### 7. What others can borrow

- **Port the tech to sports with similar motions.** Baseball tee hitting to golf; next could be tennis serves, cricket, or croquet/ground golf. The core model gets reused, and the store gets claimed one "〇〇 測定" keyword at a time.

- **Use Japan as the home market.** Japan's Sports Top Grossing bar is low and users are willing to pay. Localized titles that use search terms directly, plus a few micro-influencer #PR posts, can chart with little money.

- **"Automatic" is itself the value.** Automating every manual step in rival apps (tapping start and landing points, starting recordings by hand) is a differentiator good enough on its own.

- **Aggressive pricing + auto-renewing trials.** These can quickly push chart rankings up, at the cost of bad reviews and refund risk.

### 8. Still unclear

- Actual subscription prices (how much weekly, how much annual). The in-app purchase list wasn't captured from the App Store web page; only the "weekly-only" tier is known from reviews.

- Whether they run Apple Search Ads or Meta / TikTok ads.

- How much of the 20k downloads come from long-time baseball users; whether and when the US market takes off (currently 26 ratings).

- Whether negative reviews after November (accuracy, auto-charging) will drag down conversion.

### Sources

- App Store pages and iTunes lookup / search (jp, us, kr, tw, 2026-11-06)

- Our appstore database: app_profile, app_day, chart_rank, review, v_chart (2026-10-28 to 11-06)

- Developer engineer's note: [note.com/lllttt06/n/nb9173e6f99f0](https://note.com/lllttt06/n/nb9173e6f99f0) (2026-10-31)

- Official note: [note.com/smartscout/n/na6f97732b1f4](https://note.com/smartscout/n/na6f97732b1f4) (2026-08-31)

- Knowhere company history: [career.knowhere.co.jp/25d17803d1ab8080ab30dd4ec1682d2b](https://career.knowhere.co.jp/25d17803d1ab8080ab30dd4ec1682d2b)

- Mizuno partnership: [jpn.mizuno.com/baseball/products/smart-scout](https://jpn.mizuno.com/baseball/products/smart-scout); [prtimes.jp/main/html/rd/p/000000007.000102487.html](https://prtimes.jp/main/html/rd/p/000000007.000102487.html); [x.com/HisashiIt710/status/2021812960533131363](https://x.com/HisashiIt710/status/2021812960533131363)

- Golfboy official site: [golfboy.jp/ja/](https://golfboy.jp/ja/)

- Instagram: @smarttrackgolf (794 followers); @akane_climb #PR reel [www.instagram.com/reel/DfHNbYyMQ_F/](https://www.instagram.com/reel/DfHNbYyMQ_F/); [www.instagram.com/reel/DfA7XGvS2OU/](https://www.instagram.com/reel/DfA7XGvS2OU/); [www.instagram.com/p/DefCGIrmEmH/](https://www.instagram.com/p/DefCGIrmEmH/)

- TikTok (TikHub searches for "SmartTrack Golf", "smarttrackgolf", "弾道測定 アプリ", 2026-11-06)

- Yahoo Chiebukuro (SmoothSwing "only shows trajectory"): [detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1129193345…](https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q11291933451)

- Meta ad library (our metaads library, no records); x-radar (no records)

This article was written by AI from public data and the data we collect daily. Numbers are sourced, and inferences are labeled.