Calibre Sync
56
Quality Score
Solid
Calibre Sync
by BIL studio
Medium confidence
✍️ Bumetric analysis
“
Calibre Sync is an iOS app from BIL studio in the Utilities category, currently rated 3.3★ across 439 ratings. Initial signal reads as largely positive sentiment, users highlighting consistency and feature depth.
Quality Score is 56: Solid (established niche player). For a Utilities app, that means established niche player. The full BU Investment Matrix below scores 8 dimensions including monetisation, growth, and operational risk.
Track changes month-over-month in the Performance section below: live snapshot history and revenue forecast included.
💰 Monthly revenue · now vs forecast
● Right now
$5.0K
per month
→
12-mo forecast
$5.2K – $10.8K
per month
→
24-mo forecast
$6.4K – $19.2K
per month
MID tierSUBSCRIPTION
💡 Grow this revenue
Free AI audit of this app’s store listing
- Title & subtitle keyword fit
- Description hook & conversion structure
- Screenshots, ratings, reviews strategy
Typical impact: +2-5× organic installs
📊 Performance Tracking LIVE
22 snapshots on record
Rating
3.3
Reviews
439 reviews
Forecast Revenue / mo
$5.0K
Snapshots tracked
22
since Apr 2022
🤖Also on Android
$143/mo · 62 ratings · 4.2★
View →
ONE-TIME · BUILD
💰 Estimated build cost
$110K
↳ What it cost to build · not monthly revenue
Likely range $80K – $150K
$25K · MVP floor
$100K · indie scale
$500K+ · studio build
📈
Pays back in ~1.8y at current MRR
Synthetic estimate. Inputs: category complexity, file size, screen count, monetization layer, platform reach, age × team-size proxy. Calibrated against 2024-2026 indie-agency rate surveys. Full math + source list on /methodology.
Where the money goes
| 🧱 MVP baseline (design + 1-store ship) | +$28K |
| 📱 5 unique screens × $4.5K | +$22K |
| 📦 Asset bundle (136 MB) | +$34K |
| ⚙ Utilities complexity ×0.85 | $-12732 |
| ⚙ 6.4y maintenance × ~1-person team | +$38K |
Total estimate
$110K
ONE-TIME · EXIT VALUE
💵 Estimated acquisition value
$50K
↳ What it would sell for · not monthly revenue
Marketplace range $45K – $75K · 12× MRR multiple
💸
~0.5× build cost (under-water)
Synthetic estimate. Multiple band derived from ad-supported + age, rating quality, category demand, and user-base maturity. Calibrated against 2024-2026 indie-app-marketplace closed-deal medians. Full math + comparable deal list on /methodology.
How the multiple was built
| 📺 Ad-supported base | 15× MRR |
| 📅 6.4y proven track record | +20% |
| ⭐ ★ rating < 3.5 (weak) | -18% |
| 🏷 Utilities category multiple | -10% |
| ⭐ Small user base (<1K ratings) | -8% |
Final multiple
12× MRR
👥 Estimated audience size
61K
Lifetime downloads (US-equivalent)
Monthly active
8.9K
Daily active
1.7K
Synthetic estimate from ratings × category benchmarks. Calibrated against 2024-2026 mobile-attribution retention + DAU/MAU reports. Numbers are US-storefront-equivalent — true global audience can be 5-10× larger for international apps. Full math + source list on /methodology.
How we sized it
| 📲 Utilities engagement | ~200 installs / rating |
| 📅 6.4y of rating accumulation | -30% |
| 🔁 Utilities D30 retention | 20% |
| 📍 DAU / MAU stickiness | 0.20 |
DAU / MAU
19% sticky
🛠 Estimated tech stack
🍎
Native iOS (SwiftUI)
Medium confidence · 60%
Also possible
React Native
Flutter
Heuristic guess from app bundle size, category, store description signals, and release-date stack era. Bumetric does not disassemble binaries — for binary-level certainty you would need an SDK intelligence tool or the manifest itself. Reasoning chain on the right. Full ruleset on /methodology.
Signals we read
| 📦 App bundle size | 136 MB |
| 🏷 Category context | Utilities |
| 📦 Mid-large iOS bundle | → Likely native SwiftUI (post-2020 era) |
💀 Maintenance status
Slowing
25%
Last shipped 2026-08-12 · 43 days ago
0 · Active
50 · At risk
100 · Abandoned
Heuristic risk score from time-since-last-update + ratings velocity proxy + Editor's Choice / curated featuring signals. Calibrated against 2024-2025 app-store ranking decay reports. Not a guarantee — a quiet app with a healthy codebase looks the same as an abandoned one until something breaks. Full math on /methodology.
Risk signals
| 📅 43 days since last update | Healthy release cadence |
| 👥 Small user base (439 ratings) + 6.4y old | +10% (solo-project pattern) |
Verdict
Slowing
🔬
How we forecast this revenue
MEDIUM CONFIDENCEBaseline
$5.0K/mo · ML-estimated from 234 triggers
Growth rate
+4.0% MoM · MID tier baseline (compound monthly)
Direction
Tailwinds: monetization model proven
6 months
$4.7K – $7.9K
12 months
$5.2K – $10.8K
24 months
$6.4K – $19.2K
Compound growth at +4.0% MoM (tier baseline for MID). Range widens with horizon — typical noise band ±25% at 6mo.. Ranges widen with horizon — distant futures carry more uncertainty.
📊
BU Investment Matrix
Below median · 45/100MID TIERSUBSCRIPTIONunderperforming peersRevenue Strength
3.7
Product Quality
4.6
Market Position
2.0
Growth Velocity
5.0
Defensibility
6.1
Operational Safety
0.0
Founder Strength
5.2
Monetization Maturity
9.5
- 💰 Revenue: Modest — $3K - $7K/mo · MID tier · medium confidence, trajectory unclear.
- ⭐ Quality: 3.31★ across 439 reviews — below category median.
- 📍 Market: Not yet charting in any of the 9 monitored markets.
- 📈 Growth: Insufficient signal to assess trajectory.
- ⚠️ Risk: High — 6.7% refund mentions, scam/fraud mentions detected, bug mentions above category norm.
🎯 For competitors: Vulnerable. Quality drift + slow updates create a clear opening for a fresh competitor with active dev cadence.
💵 For acquirers: Estimated asking range 12-22× monthly = $60K-$110K. Portfolio play ($14K/mo combined) commands premium. Discount applied for operational risk..
Composite of 8 dimensions computed deterministically from public signals — no LLM, every score traces back to a measurable input. Default weights shown; "compete" / "acquire" / "invest" lenses re-weight without re-fetching.
Range:
💰 Forecast Revenue / mo
MODELRevenue forecast computed from BU's 234 trigger model on each snapshot. Calibrated against ground-truth from 58 verified-revenue apps.
🔬Forecast Breakdown — Why This Estimate?Top 6 of 6 triggers
Our ML model uses 200+ signals from public data. These are the most influential for this app:
| Paid app ($5.49)METRIC | +$2,800 | |
| subscriptionREVIEW | +$2,500 | |
| Below-average rating (3.3★)METRIC | −$1,500 | |
| Established app (6y old)METRIC | +$800 | |
| Early-stage install base (439 ratings)METRIC | +$400 | |
| Single-language (English only)METRIC | −$400 |
METRIC = structural app data · REVIEW = mined from user reviews · ✓ VERIFIED = Stripe-verified anchor (TrustMRR)
📈 Reviews Growth
LIVECumulative review count from first BU snapshot. Each point = a tracked update.
⭐ Rating Trend
LIVEAverage rating evolution. Updates with each new review batch.
Profile & Insights
Everything we know — and don't — about this app and its company.
Identification
- App name
- Calibre Sync
- Developer
- BIL studio
- Bundle ID
- com.trucnguyen.calibresync
- App Store URL
- Open in App Store
- Category
- Utilities
- Content rating
- 4+
- Languages
- EN
Company
- Website
- calibresync.bitbucket.io
- Tagline
- Calibre Sync
- Description
- All in one Calibre libraries
- Founded
- Not found
- HQ / Address
- Not found
- Employees
- Not found
- Logo
- Not found
Revenue
- Reported revenue signal / mo
- Not found
- AI revenue estimate / mo
- Not found
- AI annual estimate
- Not found
- Model estimate / mo
- $5.0K/mo
- Top-grossing rank
- Outside top 100 in US Utilities
- All-time revenue
- Not found
- Pricing
- Not found
Founder
Founder data not yet collected for this app.
Funding
Funding data not yet collected for this app.
Press & Links
Press & Links data not yet collected for this app.
Contacts & Socials
- Socials
- youtube youtube.com/@calibresync6405
- calibre.sync.help@gmail.com
- Phone
- Not found
- Contact page
- Not found
- About page
- Not found
📈Ratings growth439 ratings+21850% lifetimeShow 3-year history estimate ▾
Tracked (22 weeks) Pre-tracking estimate (0 weeks) · model-based, ±5% noise · anchored to release date and current value
🌍Geographic ReachNot ranked
This app is currently outside the top 100 grossing in all 9 countries we monitor (US, UK, DE, FR, JP, CA, AU, BR, IN). Niche or new apps often launch this way — popularity rankings appear once daily revenue clears the regional threshold.
💰Pricing History$0.00 → $5.49 (+0%)
🚀Update Frequency · Releases per Quarter4 releases tracked
🚀Version Release Timeline4 releases tracked
Profile is built from iTunes Lookup + developer site scrape + ML revenue model. Empty fields show "Not found" — additional sources (Crunchbase, X, IndieHackers, Acquire.com) coming.
📝 About this app
Lifetime support, no extra charge, no subscription fee.
Calibre Sync can:
- help you access full Calibre libraries on most popular personal cloud services, including Google Drive, Dropbox, Microsoft OneDrive, Box, pCloud, MEGA, WebDav, Nextcloud, OwnCloud, TeraBox and Proton Drive - simply the most supported for cloud services.
- transform your device to a smart device emulator that connects to Calibre wirelessly. It even supports Calibre libraries on your external storage and from Calibre Content Server with amazing performance.… View full description on the official store →
Calibre Sync can:
- help you access full Calibre libraries on most popular personal cloud services, including Google Drive, Dropbox, Microsoft OneDrive, Box, pCloud, MEGA, WebDav, Nextcloud, OwnCloud, TeraBox and Proton Drive - simply the most supported for cloud services.
- transform your device to a smart device emulator that connects to Calibre wirelessly. It even supports Calibre libraries on your external storage and from Calibre Content Server with amazing performance.… View full description on the official store →
App Specs
🔐 Own this app? Claim & verify MRR →💾 136 MB🔞 4+📱 iOS 10.0+🔖 v6.10.6🔄 updated 1mo ago🌐 EN📂 Utilities💰 Paid🚀 Launched 2020 (6y old)
📅
What Worked™ · Development Pipeline
19 EVENTS TRACKEDDetected changes in this app over its tracked lifetime — each event links cause (what changed) to effect (what moved). Sorted newest first.See full history →Version history →
2026-08
🔧
Shipped update — v6.10.4 → v6.10.6
2026-07
💲
Price ↑ $4.99 → $5.49 (+10%)
2026-07
📈
Crossed 100 ratings — social-proof flywheel kicking in
2026-07
⭐
Rating ↓ 3.75 → 3.31 (dropped 0.44★)
2026-07
📸
Refreshed store screenshots — 8 of 8 updated
2026-07
🔧
Shipped update — v6.9.2 → v6.10.4
→ 30 days after: revenue −$287/mo · rating −0.44★ · reviews +386 high confidence
2026-06
📦
Bundle ↑ 102MB → 141MB — likely major code refresh
→ 30 days after: revenue −$287/mo · rating −0.44★ · reviews +385 high confidence
2026-06
🔧
Shipped update — v6.8.5 → v6.9.2
→ 30 days after: revenue −$287/mo · rating −0.41★ · reviews +388 medium · co-occurring
2026-05
💲
Went paid — introduced $4.99 price point
2026-05
⭐
Rating ↑ 3.40 → 3.72 (improved 0.32★)
2026-05
📈
Crossed 50 ratings — social-proof flywheel kicking in
2026-03
⭐
Rating ↑ 3.04 → 3.40 (improved 0.36★)
2022-11
📈
Crossed 10 ratings — social-proof flywheel kicking in
→ 30 days after: rating +0.14★ high confidence
2022-10
⭐
Rating ↓ 3.88 → 3.56 (dropped 0.32★)
→ 30 days after: rating −0.06★ high confidence
2022-10
⭐
Rating ↓ 4.17 → 3.71 (dropped 0.46★)
→ 30 days after: rating −0.67★ medium · co-occurring
2022-08
⭐
Rating ↓ 5.00 → 4.17 (dropped 0.83★)
→ 30 days after: rating −0.61★ medium · co-occurring
2022-08
⭐
Rating ↓ 5.00 → 4.50 (dropped 0.50★)
→ 30 days after: rating −0.83★ medium · co-occurring
2022-04
🚀
First tracked snapshot — initial data captured
2022-04
🚀
First tracked snapshot — initial data captured
📸
Store Page History
8 SCREENSHOT CHANGESEvery time a developer swaps a store screenshot we archive both versions. Compare side-by-side to see what messaging / visuals changed.
iPhone screenshots
Slot 1
2 ver.
2 ver.
2026-05-12
2026-07-30
Slot 2
2 ver.
2 ver.
2026-05-12
2026-07-30
Slot 3
2 ver.
2 ver.
2026-05-12
2026-07-30
Slot 4
2 ver.
2 ver.
2026-05-12
2026-07-30
Slot 5
2 ver.
2 ver.
2026-05-12
2026-07-30
Slot 6
2 ver.
2 ver.
2026-05-12
2026-07-30
🗣
Voice of Customer
Based on 30 reviews across 2 markets● 73% positive · ● 3% neutral · ● 23% negative · Rating drift: +0.19★ (improving — recent 50: 3.5★ vs lifetime: 3.31★)
Sentiment by country (−1 to +1)
🇺🇸 US
+0.40
🇨🇦 CA
+0.23
Top praise themes
library ×11 works ×7 books ×6 cloud ×5 connect ×4 new ×4 without ×4 access ×4
Top complaint themes
doesnt work ×3 works ×5 file ×4 new ×3 update ×3 ipad ×3 support ×3 read ×3
Risk signals
Refund mentions: 6.7% Subscription complaints: 3% Bug mentions: 10% Fraud / scam mentions: 3.3%
🌍
Multi-Country Performance
Available in 9 of 9 monitored markets| Market | Rating | Reviews | Current version |
|---|---|---|---|
| 🇺🇸 US | 3.94545★ | 55 | 3.94545★ this version |
| 🇬🇧 GB | 3.5★ | 8 | 3.5★ this version |
| 🇩🇪 DE | 4.44444★ | 18 | 4.44444★ this version |
| 🇫🇷 FR | 3.61538★ | 13 | 3.61538★ this version |
| 🇯🇵 JP | 3★ | 2 | 3★ this version |
| 🇨🇦 CA | 3.75★ | 4 | 3.75★ this version |
| 🇦🇺 AU | 3.8★ | 5 | 3.8★ this version |
| 🇧🇷 BR | 3.5★ | 2 | 3.5★ this version |
| 🇮🇳 IN | 2★ | 1 | 2★ this version |
🔔
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📝 Description
95
BU Score · Transcendent
Full revenue analysis
Read the article-style breakdown for Calibre Sync: category rank, percentile, growth signal, comparable apps, and how the forecast is calibrated against verified-MRR anchors in this niche.
About this analysis
Why medium confidence: 439 ratings · no founder-verified revenue (model estimate only).
❓ Frequently Asked Questions
10 answers · auto-generated from this app's public dataHow much does Calibre Sync make per month?▴
Based on our ML-calibrated revenue forecast, Calibre Sync earns approximately $5.0K/mo. This is a US-storefront-equivalent estimate; global revenue can be several times larger for internationally-distributed apps. See the methodology page for the full formula and confidence bands.
Is Calibre Sync profitable?▴
With estimated build cost $110K and monthly revenue $5.0K, Calibre Sync looks break-even-grade — payback period sits around 1.8 years. Profitability also depends on paid-acquisition spend and refund rate which the public model doesn't see.
How many users does Calibre Sync have?▴
Estimated audience: ~61K lifetime downloads, ~8K monthly active users, and ~1K daily active users. Derived from ratings count × category installs-per-rating × age decay. US-storefront-equivalent — global audience can be 5-10× larger for internationally-distributed apps.
What apps are like Calibre Sync?▴
Browse the full Utilities category catalog to find similar apps with revenue, build cost, audience and tech stack data. Each /p/{slug} page also shows a Compare side-by-side widget with three peer apps from the same niche.
What is Calibre Sync built with?▴
Our heuristic places Calibre Sync on the Native iOS (SwiftUI) stack (Medium confidence, 60%). Signals: app bundle size, category context, store-description markers, release-date era. We don't disassemble binaries. Alternative possibilities: React Native, Flutter.
Is Calibre Sync still actively maintained?▴
Maintenance status: Slowing (25% abandonment risk). Last shipped version was 1 months ago. The risk score combines time-since-last-update with Editor's Choice / curated featuring + user-base maturity adjustments.
How much would Calibre Sync sell for?▴
Estimated acquisition value: $50K (marketplace range $45K – $75K). Calculated as 12× monthly revenue using the standard multiple for the detected monetization model + adjustments for age, rating quality and category demand. Calibrated against 2024-2026 Flippa / Acquire.com / MicroAcquire closed-deal medians.
When was Calibre Sync last updated?▴
Calibre Sync last shipped a new version on 2026-08-12 — 1 months ago. This is the date Apple / Google last accepted a new build, not a content-only push.
Who makes Calibre Sync?▴
Calibre Sync is published by BIL studio on the Apple App Store. See the full publisher portfolio (other apps by the same developer) via the More by developer block on the product page above.
What is Calibre Sync's BU Score?▴
Calibre Sync has a BU Score of 56/100 (Solid). The score combines App Store rating, ratings count, monetization model and revenue signals calibrated against founder-verified MRR anchors. See the BU Score formula.