mem Downloads & Revenuemem · App Store
Not in any tracked top chart right now.
Updated 11 Nov 2026 · rankings refresh through the day
DeveloperCatalystwo
CategoryReference
Price800 JPY
Released
Rating★ 3.7 (19)
Version2.1.11
Age rating17+
First seen by us
26 Sep 2026
26 Sep 2026Installs (est.)1k+ worldwide
Full timeline · 2 events in the last 12 months
- 🆕mem first spotted by AppInsider#37 in Top Paid · Reference · Japan
- 🆕mem released on the App Store
Collected from the stores by AppInsider since we first spotted the app. Dates are when we saw each change.
Rating
3.7 ★
19 ratings
Measured
mem on the App Store
App details
App ID
777510569
Publisher
Catalystwo, LLC
On the store since
Feb 2014
12 years on the store
Minimum OS
iOS 13.0+
iPhone 6s and later
Devices
iPhone · iPad
Universal purchase
Content rating
17+
1 content note below
Languages
3
EN JA MI
Size
14 MB
Also listed in
Education
Content notesUnrestricted Web Access
mem downloads
Worldwide, per day, and installs to date. The band is open; the exact number is free with an account.
How this is calculated
Apple publishes no download counts. App Store downloads come from chart positions and daily rating growth per country, calibrated on Google Play install counts; lifetime installs from ratings worldwide × installs per rating. Confidence is the chance the real number is within half to double ours.
Active users
All platforms, worldwide. Free with an account.
Stickiness (DAU / MAU)
how many monthly users open it on a given day
How this is calculated
Monthly users come from lifetime installs across every store, fitted on monthly active user figures companies publish; daily users = monthly × the typical daily/monthly ratio for the category. Confidence is the chance the real number is within half to double ours.
Where it ranks now
Every top chart it appears in across 30 countries.
| Country | Charts | Rank |
|---|---|---|
| Not charting right now. | ||
Ratings
App Store, worldwide.
Rating
3.7 ★
19 ratings
Measured
Ratings
19
Measured
Review momentum
ⓘ How we measure thisNew ratings a week
under 1
4-week average
Lifetime rating
3.7★
recent stars not readable yet: new ratings are a tiny share of the total
Review momentum
20/100
faster than 0% of Reference apps
Review momentum (0-100) blends how fast the app collects ratings compared with other apps in its category (60%), whether that pace is speeding up (25%) and what recent raters give it (15%; recent stars well below lifetime pull it down). Ratings counts are read daily. A jump usually means a launch, a feature, ads or a new review prompt.
About mem
"Leitner's System" is a memory tool designed by Sebastion Leitner in 1972, using flash cards to memorise words or phrases. It is a simple implementation of the principle of spaced repetition, where cards are reviewed at increasing intervals.
"Hand Computer" app is designed to simulate the Leitner system and is a simple, convenient and effective memory tool for any foreign language student or simply a tool to help you study and remember any subject.
When you find a word or phrase or equation you don't know, add it to a card after you have memorised it, then add the card to the first compartment.
Review the cards in the first compartment a few times each day when you have time. If you still remember it, move the card to the next compartment. If you have forgotten it, put it back.
After a few days or when the second compartment is full, review the cards in that compartment. If you have forgotten anything, put it back to the first compartment.
The capacity of each compartment is optimised to recall your memory efficiently and effectively. The frequency you review each word increases as it proceeds through the compartments for more effective learning.
The last compartment can hold as many cards as you want, but it is best that you review them from time to time.
*If you are interested in this app, try "Cards" app from us.*
For more information, please read:
http://en.wikipedia.org/wiki/Spaced_repetition
http://en.wikipedia.org/wiki/Leitner_system
Launch URL scheme for this app
comcatalystwohandcomputer
Demo Video:
http://vimeo.com/84745906
• Graphically visible stored cards to motivate you.
• Non-proprietary file format... Documents are saved in plain text CSV file.
• Synchronize via Dropbox. ... You can edit documents on your Mac/PC.
• Night Mode is gentle on your eyes when studying in the middle of the night.
• Listen to the word to improve your memory.
= How to scan your own cards =
1. Tap “+” button to open “Add” page
2. Tap Camera button
3. Choose “Scan Multiple Cards” then follow the guide.
= How to add multiple words using Dropbox =
Prepare Mac/PC with Dropbox installed.
Create a file like this…
--------
Word1, Its definition
Word2, Its definition
Word3, Its definition
.
.
.
--------
Save this file in Hand Computer folder in Dropbox with csv extension.
TECHNICAL INFORMATION
This application includes
Re-written in SceneKit with CAAnimation in version 2 instead of full CALayer + CoreAnimation in version 1.
59,000 lines of ObjC codes
6,900 lines of ORIGINAL Swift codes
OpenCL image processing
Supports Wacom Intuos Bamboo stylus using CoreBluetooth
"Hand Computer" app is designed to simulate the Leitner system and is a simple, convenient and effective memory tool for any foreign language student or simply a tool to help you study and remember any subject.
When you find a word or phrase or equation you don't know, add it to a card after you have memorised it, then add the card to the first compartment.
Review the cards in the first compartment a few times each day when you have time. If you still remember it, move the card to the next compartment. If you have forgotten it, put it back.
After a few days or when the second compartment is full, review the cards in that compartment. If you have forgotten anything, put it back to the first compartment.
The capacity of each compartment is optimised to recall your memory efficiently and effectively. The frequency you review each word increases as it proceeds through the compartments for more effective learning.
The last compartment can hold as many cards as you want, but it is best that you review them from time to time.
*If you are interested in this app, try "Cards" app from us.*
For more information, please read:
http://en.wikipedia.org/wiki/Spaced_repetition
http://en.wikipedia.org/wiki/Leitner_system
Launch URL scheme for this app
comcatalystwohandcomputer
Demo Video:
http://vimeo.com/84745906
• Graphically visible stored cards to motivate you.
• Non-proprietary file format... Documents are saved in plain text CSV file.
• Synchronize via Dropbox. ... You can edit documents on your Mac/PC.
• Night Mode is gentle on your eyes when studying in the middle of the night.
• Listen to the word to improve your memory.
= How to scan your own cards =
1. Tap “+” button to open “Add” page
2. Tap Camera button
3. Choose “Scan Multiple Cards” then follow the guide.
= How to add multiple words using Dropbox =
Prepare Mac/PC with Dropbox installed.
Create a file like this…
--------
Word1, Its definition
Word2, Its definition
Word3, Its definition
.
.
.
--------
Save this file in Hand Computer folder in Dropbox with csv extension.
TECHNICAL INFORMATION
This application includes
Re-written in SceneKit with CAAnimation in version 2 instead of full CALayer + CoreAnimation in version 1.
59,000 lines of ObjC codes
6,900 lines of ORIGINAL Swift codes
OpenCL image processing
Supports Wacom Intuos Bamboo stylus using CoreBluetooth
Latest updates
2.1.11
Chaged keywords
