Comparison

Note Lock ~ Keep your secret vs NPSH Calculator

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Note Lock ~ Keep your secret

Securely store and manage private notes, ideas, and journals with advanced locking mechanisms and privacy features. Organize your thoughts with rich media, customization options, and backup capabilities.

Highlights
  • Folder and pattern lock
  • Anti-intruder surveillance
  • Self-destruct data option
  • Add pictures and stickers
  • Customizable themes and fonts
  • Backup and restore data
  • Calendar and hybrid views
Features
Read full description

THE BEST NOTE LOCK APP EVER * TRUSTED OVER 2,800,000 USERS AROUND THE GLOBE. TOP 100 CHART IN MORE THAN 100 COUNTRIES. DECOY PASSCODE PROTECT YOU FROM FORCE UNLOCK. :: NEW! Recently Deleted recover notes you deleted by mistake before they are permanently removed. :: NEW! Calendar View and Hybrid view! :: Protect your private notes with Note Lock :: Separate your secret notes from device note :: Safely store and manage unlimited secret collections :: More exciting and fun with pencil + eraser animations :: Create new notes, add pictures and save to the app. :: Add fun and ease of use with stickers and sticky notes :: Lecture notes, business notes, secret notes, secret ideas or information, private journal with pictures and description, class lecture, love letter, diary and many more. :: Personal diary on your iPhone :: Backup your information to use in case your device is ever replace, lost or damaged. SOME OF HUNDREDS REVIEW FROM USERS WHY THEY LOVED NOTE LOCK? - "The pencil feature and the dust is amazing!" - "Great app to put my thoughts in and keep them for only my interpretation." - "I get carried away, i write the littlest detail like, what i had for dinner, etc. It's so easy to use. I strongly recommend." - "Just wrote my 10 page term paper on this bad boy, love it. Just copied and pasted and emailed it to myself and made all the font adjustments there." - "I have tried at least 20 other apps and this one is the best." - "Does all I want and more, worth the money MORE FEATURES: SECURITIES: - Lock Type: Folder Lock, Super discreet in iOS13 folder style. - Surveillance system, enter wrong passcode or pattern 3 times your recorded security camera will appear. - Anti Intruder System, any break-attemp will captured with photo&video and date&time. - Self-Destruction, 5 chances to correct passcode. After that, the app will automatically erase all data in this app. (Default is off) - Back up passcode to your e-mail. - Lock2 Technology: Passcode, Pattern lock and new folder lock! - Lock when inactive. - Double account to fool intruders. NOTE FEATURES • Recently Deleted for recovery • Sticky notes inside notes • Add stickers, themes, and font colors • 300+ fonts and 30+ themes • Improved search and sorting by date/month • Photo attachments and gallery preview • Email sharing ACCESSORIES: - Theme selection: more than 30 themes - Font selection: more than 300 font formats - More fun with pencil and eraser animations - Support landscape orientation - Discrete app name BENEFITS from Note Lock - For business purposes - Secret ideas or information - Private journal with pictures and description - Class lecture - Love letter - And many more ... - Diary Note Lock Pro With a Note Lock Pro subscription, you have unlimited access to all features Advertisements will be removed automatically Access all lock styles. Unlimited notes can be added. Unlimited use of Sticky note Unlimited access to Sticker Unlimited access to all themes and fonts Secure backup & sync your notes And many more If you upgrade Note Lock Pro subscription, payment will be charged to your iTune account. And your account will be charged for renewal 24-hours prior to the endow the current period. Subscriptions may be managed by you and auto-renewal may be turned off by going to the your Account Settings after purchase. Any unused portion of a free trial period, if offered, will be forfeited when you purchases a subscription. Please read our Privacy Policy for further information. Privacy Policy : https://iappcreation.com/privacy-policy/nl Terms and Conditions : https://iappcreation.com/privacy-policy/nl#terms

About

NPSH Calculator

Features
Read full description

Will your centrifugal pump cavitate? NPSH Calculator answers that question with your real suction data. Enter your suction line (length, flow, diameter, material and fittings) and the site conditions (liquid temperature, altitude, suction static head). The app calculates the NPSH available at the pump suction, compares it with the NPSH required by your pump and gives you a clear verdict. CAVITATION CHECK + NPSH CURVE • Color-coded verdict: OK, Marginal or Cavitation • Full NPSH available vs. flow curve with your pump's NPSHr overlaid • Maximum safe flow: the exact point where NPSH available drops below NPSHr ACCURATE HEAD LOSS AT ANY TEMPERATURE • Darcy-Weisbach friction (Swamee-Jain), not a fixed 20 °C formula • Water density, viscosity and vapor pressure computed from the temperature (0–100 °C) • Reynolds number and flow regime • 14 pipe materials with real roughness, or your own value • Suction fittings with K coefficients: foot valve, check valve, elbows, tees, reducers, valves REPORTS AND PROJECTS • Export a complete PDF report with inputs, results, verdict and curve • Save and reopen projects by name NPSH INDUSTRIAL (in-app purchase) • 20 industrial fluids: seawater, glycols, caustic soda, gasoline, diesel, crude oil, solvents, sulfuric acid, and saturated LPG (propane, butane), ammonia, CO2 and R-134a, plus a custom fluid • Atmospheric, pressurized and saturated tank modes, with the saturated case handled correctly US and SI units with automatic conversion. Available in 9 languages. Works offline. Note: intended for preliminary calculations and education. Always confirm final designs and pump selections with a qualified engineer and the pump manufacturer.

Screenshots

Note Lock ~ Keep your secret4 screens
NPSH Calculator4 screens

Verdict

The call

The clearest difference is iOS requirement: NPSH Calculator at 15.1 against Note Lock ~ Keep your secret's 17.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Note Lock ~ Keep your secret costs $1.99 and NPSH Calculator $1.99 up front. Note Lock ~ Keep your secret sells 10 in-app purchases, starting at $1.99 per month and NPSH Calculator sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Note Lock ~ Keep your secret ships an update every 2 months, NPSH Calculator every 3 months. The most recent releases landed on November 10, 2026 and October 30, 2026 respectively.

Scorecard1 real difference · 9 level
Note Lock ~ Keep your secret versus NPSH Calculator: the parameters behind the verdict, then further details
ParameterNote Lock ~ Keep your secretNPSH Calculator
Price$1.99$1.99
Rating4.0 (154 ratings) — better—
Positive reviews53.0% of reviews—
Number of ratings154 — better—
Update frequencyEvery 2 months — betterEvery 3 months
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchases—
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.015.1 — better
Further details — not scored
Size52 MB34 MB
Age rating+44+
Developeri-App Creation Co., Ltd.Transparent Blue Water LLC

Bugs and requests

Note Lock ~ Keep your secret

Reported bugs

3 issues
  • App crashes when opening notes
  • Unable to rotate screen in landscape mode
  • Password reset and migration issues when switching devices

Requested features

4 requests
  • Search function to easily find notes
  • Ability to organize notes into folders
  • Syncing and backup options (e.g., iCloud)
  • Customization options for fonts, themes, and layouts

NPSH Calculator

Not enough reviews yet to summarise bugs or requests.

In-app purchases

10 purchases

Note Lock ~ Keep your secret

Subscriptions2
  • Note Lock PRO - Monthly3 Days trial$1.991 Month
  • Note Lock PRO - Yearly$9.991 Year
One-time8
  • Pro Fonts$1.99
  • Special Fonts$1.99
  • Unique Fonts 1$1.99
Show 5 more
  • Unique Fonts 3$1.99
  • Cute Fonts$1.99
  • Unique Fonts 2$1.99
  • Unlock All Fonts$6.99
  • Unlock All In-app$29.99
1 purchases

NPSH Calculator

One-time1
  • NPSH Industrial$4.99

Questions

Is Note Lock ~ Keep your secret free?
Note Lock ~ Keep your secret costs $1.99, and also offers in-app purchases.
Is NPSH Calculator free?
NPSH Calculator costs $1.99, and also offers in-app purchases.
Do Note Lock ~ Keep your secret or NPSH Calculator have ads?
Neither Note Lock ~ Keep your secret nor NPSH Calculator shows ads.
Which is updated more often, Note Lock ~ Keep your secret or NPSH Calculator?
Note Lock ~ Keep your secret ships an update every 2 months, and NPSH Calculator every 3 months. Most recently, Note Lock ~ Keep your secret was updated on November 10, 2026 and NPSH Calculator on October 30, 2026.

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