Proton Calendar
60
Quality Score
Solid
✍️ Bumetric analysis
“
Proton Calendar is an iOS app from Proton AG in the Productivity category, currently rated 3.9★ across 1,193 ratings. Initial signal reads as largely positive sentiment, users highlighting consistency and feature depth.
Quality Score is 60: Solid (established niche player). For a Productivity 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 tierFREE
💡 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
99 snapshots on record
Rating
3.9
Reviews
1,193 reviews
Forecast Revenue / mo
$5.0K
Snapshots tracked
99
since Nov 2022
ONE-TIME · BUILD
💰 Estimated build cost
$120K
↳ What it cost to build · not monthly revenue
Likely range $90K – $160K
$25K · MVP floor
$100K · indie scale
$500K+ · studio build
📈
Pays back in ~2.0y 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 (185 MB) | +$40K |
| ⚙ Productivity complexity ×1.10 | +$9K |
| ⚙ 3.8y maintenance × ~1-person team | +$22K |
Total estimate
$120K
ONE-TIME · EXIT VALUE
💵 Estimated acquisition value
$100K
↳ What it would sell for · not monthly revenue
Marketplace range $75K – $125K · 18× MRR multiple
💸
~0.8× 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 |
| 📅 3.8y proven track record | +19% |
| ⭐ ★ rating 3.5-4.0 (mixed) | -8% |
| 🏷 Productivity category multiple | +8% |
Final multiple
18× MRR
👥 Estimated audience size
72K
Lifetime downloads (US-equivalent)
Monthly active
19K
Daily active
8.5K
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
| 📲 Productivity engagement | ~75 installs / rating |
| 📅 3.8y of rating accumulation | -19% |
| 🔁 Productivity D30 retention | 30% |
| 📍 DAU / MAU stickiness | 0.45 |
DAU / MAU
45% 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 | 185 MB |
| 🏷 Category context | Productivity |
| 📦 Mid-large iOS bundle | → Likely native SwiftUI (post-2020 era) |
💀 Maintenance status
Slowing
30%
Last shipped 2026-06-03 · 114 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
| 📅 3 months since last update | Slowing cadence |
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)
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 · 47/100MID TIERFREE (NO MONETIZATION)underperforming peersRevenue Strength
3.7
Product Quality
5.6
Market Position
2.0
Growth Velocity
5.0
Defensibility
6.0
Operational Safety
7.0
Founder Strength
7.6
Monetization Maturity
0.5
- 💰 Revenue: Modest — $3K - $7K/mo · MID tier · medium confidence, trajectory unclear.
- ⭐ Quality: 3.94★ across 1,193 reviews — below category median.
- 📍 Market: Not yet charting in any of the 9 monitored markets.
- 📈 Growth: Insufficient signal to assess trajectory.
- ⚠️ Risk: Moderate — 5% subscription complaints, rating drift -1.02 ★ (recent 50 vs lifetime).
🎯 For competitors: Mixed picture. Worth competing if you have a clear UX or pricing edge — otherwise crowded segment.
💵 For acquirers: Estimated asking range 18-32× monthly = $90K-$160K. Portfolio play ($127K/mo combined) commands premium.
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 8 of 8 triggers
Our ML model uses 200+ signals from public data. These are the most influential for this app:
| bugsREVIEW | −$1,800 | |
| 5 starREVIEW | +$1,800 | |
| Low install base (1,193 ratings)METRIC | +$1,500 | |
| Multilingual (26 languages)METRIC | +$1,500 | |
| highly recommendREVIEW | +$1,400 | |
| slowREVIEW | −$1,200 | |
| Established app (3y old)METRIC | +$800 | |
| Ad-supported / freemiumMETRIC | +$600 |
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.
🆕 What's New · v2.25.1
Minor bug-fixes.
Profile & Insights
Everything we know — and don't — about this app and its company.
Identification
- App name
- Proton Calendar
- Developer
- Proton AG
- Bundle ID
- ch.protonmail.calendar
- App Store URL
- Open in App Store
- Category
- Productivity
- Content rating
- 4+
- Languages
- BE, CA, CS, DA, NL, EN, FI, FR, KA, DE, EL, HU, ID, IT, KO, NB, PL, PT, RO, RU, SK, ES, SV, ZH, TR, UK
Company
- Website
- Not found
- Tagline
- Today
- Description
- Find apps and games for iPhone, iPad, Mac, and more on the App Store.
- Founded
- Not found
- HQ / Address
- Not found
- Employees
- Not found
- Logo
- Available
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 Productivity
- 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
Contacts & Socials data not yet collected for this app.
📈Ratings growth1,471 ratings+314% lifetimeShow 3-year history estimate ▾
Tracked (60 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.
🚀Version Release Timeline2 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
A calendar is a record of your life: Proton Calendar helps keep it private.
Make the most of your time
- See your upcoming events as you like with agenda or day view
- View and reply to invites
- Events and invites are automatically added to your calendar from your Proton Mail inbox
- View your schedule in light or dark mode
- Add multiple reminders for your events
- Create recurring events on a daily, weekly, monthly, yearly, or custom basis
- Keep your calendar in sync across all your devices
Private by default
- No ads, no trackers, and no data harvesting… View full description on the official store →
Make the most of your time
- See your upcoming events as you like with agenda or day view
- View and reply to invites
- Events and invites are automatically added to your calendar from your Proton Mail inbox
- View your schedule in light or dark mode
- Add multiple reminders for your events
- Create recurring events on a daily, weekly, monthly, yearly, or custom basis
- Keep your calendar in sync across all your devices
Private by default
- No ads, no trackers, and no data harvesting… View full description on the official store →
App Specs
🔐 Own this app? Claim & verify MRR →💾 185 MB🔞 4+📱 iOS 16.0+🔖 v2.25.1🔄 updated 3mo ago🌐 BE, CA, CS, DA, NL +21📂 Productivity💰 Paid🚀 Launched 2022 (3y old)
📅
What Worked™ · Development Pipeline
16 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 →
2026-06
🔧
Shipped update — v2.25.0 → v2.25.1
→ 30 days after: rating +0.08★ · reviews +162 high confidence
2026-05
📈
Crossed 500 ratings — social-proof flywheel kicking in
→ 30 days after: reviews +88 high confidence
2026-05
⭐
Rating ↑ 2.88 → 3.94 (improved 1.06★)
→ 30 days after: reviews +88 high confidence
2026-03
⭐
Rating ↓ 3.50 → 2.89 (dropped 0.61★)
→ 30 days after: reviews +8 medium · co-occurring
2026-03
📈
Crossed 500 ratings — social-proof flywheel kicking in
→ 30 days after: reviews +9 medium · co-occurring
2026-03
⭐
Rating ↑ 2.88 → 3.50 (improved 0.62★)
→ 30 days after: reviews +9 medium · co-occurring
2023-05
📈
Crossed 100 ratings — social-proof flywheel kicking in
→ 30 days after: rating −0.06★ · reviews +14 high confidence
2023-05
📈
Crossed 100 ratings — social-proof flywheel kicking in
→ 30 days after: rating −0.08★ · reviews +15 high confidence
2023-01
📈
Crossed 50 ratings — social-proof flywheel kicking in
→ 30 days after: reviews +11 high confidence
2023-01
📈
Crossed 50 ratings — social-proof flywheel kicking in
→ 30 days after: revenue +$179/mo · rating −0.19★ · reviews +57 high confidence
2022-12
📈
Crossed 10 ratings — social-proof flywheel kicking in
→ 30 days after: revenue +$144/mo · rating −0.23★ · reviews +46 high confidence
2022-12
⭐
Rating ↓ 5.00 → 3.55 (dropped 1.45★)
→ 30 days after: revenue +$144/mo · rating −0.23★ · reviews +46 high confidence
2022-12
📈
Crossed 10 ratings — social-proof flywheel kicking in
→ 30 days after: revenue +$61/mo · rating −1.45★ · reviews +19 low · multiple changes
2022-12
⭐
Rating ↓ 4.20 → 3.83 (dropped 0.37★)
→ 30 days after: revenue +$61/mo · rating −1.45★ · reviews +19 low · multiple changes
2022-12
⭐
Rating ↓ 5.00 → 4.00 (dropped 1.00★)
→ 30 days after: revenue +$61/mo · rating −1.45★ · reviews +19 low · multiple changes
2022-11
🚀
First tracked snapshot — initial data captured
→ 30 days after: revenue +$61/mo · rating −1.45★ · reviews +19 low · multiple changes
🗣
Voice of Customer
Based on 39 reviews across 1 markets● 85% positive · ● 0% neutral · ● 15% negative · Rating drift: -1.02★ (declining — recent 50: 2.92★ vs lifetime: 3.94★)
Top praise themes
view ×8 events ×6 google ×5 widget ×5 now ×3 few ×3 only ×3 upcoming ×3
Top complaint themes
one ×5 basic ×5 informant ×3 don't ×3 apple ×3 notifications ×3 ipad ×3
Risk signals
Subscription complaints: 5%
🌍
Multi-Country Performance
Available in 9 of 9 monitored markets| Market | Rating | Reviews | Current version |
|---|---|---|---|
| 🇺🇸 US | 4.07118★ | 1,489 | 4.07118★ this version |
| 🇬🇧 GB | 3.68803★ | 234 | 3.68803★ this version |
| 🇩🇪 DE | 3.68227★ | 406 | 3.68227★ this version |
| 🇫🇷 FR | 3.95946★ | 296 | 3.95946★ this version |
| 🇯🇵 JP | 3.80488★ | 41 | 3.80488★ this version |
| 🇨🇦 CA | 4.14286★ | 224 | 4.14286★ this version |
| 🇦🇺 AU | 3.92063★ | 126 | 3.92063★ this version |
| 🇧🇷 BR | 4.06667★ | 30 | 4.06667★ this version |
| 🇮🇳 IN | 4.2★ | 20 | 4.2★ this version |
🔔
Track this app’s revenue
FREEGet an email when revenue moves by your threshold. No spam, unsubscribe in one click.
📝 Description
95
BU Score · Transcendent
Full revenue analysis
Read the article-style breakdown for Proton Calendar: category rank, percentile, growth signal, comparable apps, and how the forecast is calibrated against verified-MRR anchors in this niche.
More by Proton AG
View all →📦 Portfolio summaryBIG studio
9apps·$3.5M/mocombined
✓ Diversified — top app contributes 43%; risk spread across portfolio
About this analysis
Why medium confidence: 1,193 ratings · no founder-verified revenue (model estimate only).
❓ Frequently Asked Questions
10 answers · auto-generated from this app's public dataHow much does Proton Calendar make per month?▴
Based on our ML-calibrated revenue forecast, Proton Calendar 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 Proton Calendar profitable?▴
With estimated build cost $120K and monthly revenue $5.0K, Proton Calendar looks break-even-grade — payback period sits around 2.0 years. Profitability also depends on paid-acquisition spend and refund rate which the public model doesn't see.
How many users does Proton Calendar have?▴
Estimated audience: ~72K lifetime downloads, ~19K monthly active users, and ~8K 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 Proton Calendar?▴
Browse the full Productivity 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 Proton Calendar built with?▴
Our heuristic places Proton Calendar 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 Proton Calendar still actively maintained?▴
Maintenance status: Slowing (30% abandonment risk). Last shipped version was 3 months ago. The risk score combines time-since-last-update with Editor's Choice / curated featuring + user-base maturity adjustments.
How much would Proton Calendar sell for?▴
Estimated acquisition value: $100K (marketplace range $75K – $125K). Calculated as 18× 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 Proton Calendar last updated?▴
Proton Calendar last shipped a new version on 2026-06-03 — 3 months ago. This is the date Apple / Google last accepted a new build, not a content-only push.
Who makes Proton Calendar?▴
Proton Calendar is published by Proton AG 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 Proton Calendar's BU Score?▴
Proton Calendar has a BU Score of 60/100 (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.