Comparison

RayLab vs KAKURAKU

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

Head to head
About

RayLab

Design and simulate optical systems with this powerful tool. Explore 2D and 3D models, perform advanced ray tracing, and analyze optical performance. Ideal for learning or professional design.

Highlights
  • 2D/3D optical modeling
  • Geometric ray tracing
  • Sequential and non-sequential analysis
  • Advanced optical elements
  • Polarization ray tracing
  • Design optimization
  • Glass catalogs
Features
Read full description

RayLab is an application for design and simulation of optics. It can be used either as a learning tool or for the design of real optical systems. Basic version includes: • Ability to model 2D lenses and mirrors • Full control over placement and shape of optical components • Full control over aspheric surface shape parameters • Full geometric ray tracing • Sequential and Non Sequential analysis • Front Focal Length, Back Focal Length, Principle Surface calculations • Sample Models Upgrade to RayLab Pro enables: • 3D Modeling • Advanced Optical Elements such as Lens Arrays, Diffraction Gratings, Prisms, Fresnel Lenses, etc. • Polarization Ray Tracing * Ray Splitting / Beam Splitter modeling • Multi-Configuration Manager and animation functionality • Ability to perform optimizations of design parameters • Ray Transfer Matrix calculation • Various commercial glass catalogs • Zemax Importer • Multiple Analysis Windows: -- Fan Ray Diagram. -- Wavefront Error Plot. -- Grid Distortion Plot. -- Spot Diagram. -- Chromatic Aberration. -- Gaussian Spot Size. -- Polarization Analyzer. Upgrade is available with in-app purchases of various modules OR as a full featured subscription. • The subscription offers a 7 day free trial period. Subscription begins immediately but payment will only be charged to iTunes Account at the end of the trial period. • Subscription automatically renews unless auto-renew is turned off at least 24-hours before the end of the current period. • The account will be charged for renewal within 24-hours prior to the end of the current period, at the same monthly price as the original subscription. • You may manage your subscriptions and auto-renewal may be turned off by going to your iTunes Account Settings after purchase. • No cancellation of the current subscription is allowed during active subscription period. • Any unused portion of a free trial period will be forfeited if the subscription is cancelled. Privacy Policy and Terms of Use: https://www.raymak.com/wp/privacy-policy

About

KAKURAKU

Features
Read full description

KAKURAKU is an educational app that lets you experience probability paradoxes hands-on. Answer with your gut, run the simulation hundreds of times, and compare the result with the mathematical answer. See for yourself where intuition and mathematics part ways. Developer: Fuji Bit Inc. KAKURAKU is the 10th app in the "-raku" series of educational apps, and its theme is probability. It covers 14 famous probability paradoxes, and every one of them unfolds in four phases. Four phases: 1. Gut check: Answer with your intuition first. Most people get these wrong. 2. Simulation: Run one trial at a time or hundreds at once, and see the probabilities as real numbers. 3. The answer: See the mathematical answer and why intuition misses, with diagrams and formulas. 4. Final check: Answer a new question to clear the stage. 14 probability paradoxes in 3 categories: Conditional probability traps - The Door Trap (Monty Hall Problem): Does switching doors win 2/3 of the time? - The Gold Box (Bertrand's Box): Is your 1/2 intuition wrong? - Warden's Verdict (Three Prisoners Problem): Does one word from the warden change A's fate? - Test Trap (False Positive Problem): You test positive, yet the chance you are sick is only 16%? - Sleeping Princess (Sleeping Beauty Problem): 1/2 or 1/3? People still disagree. When statistics fool intuition - Miracle Classroom (Birthday Paradox): With just 23 people, is a shared birthday more likely than not? - Reversed Statistics (Simpson's Paradox): Can the parts and the whole point in opposite directions? - The Endless Bus (Bus Waiting Paradox): Buses come every 10 minutes on average, yet you wait 10 minutes on average? - Red Chain (Gambler's Fallacy): After a run of reds, is black due? - Too Many Ones (Benford's Law) (new): Do about 30% of everyday numbers start with 1? Expected value and decisions - Envelope Dilemma (Two Envelope Problem): Should you keep switching envelopes? - Infinite Gamble (St. Petersburg Paradox): The expected value is infinite, so why would no one pay much to play? - The Predictor's Boxes (Newcomb's Paradox): One box or two? Change the predictor's accuracy and find out. - The Second Mover Wins (Penney's Game) (new): A game of guessing three-coin patterns. Can the second player win up to 7/8 of the time? Features: - Clean, modern design with dark and light themes - Home screen organized by category - Every stage advances in four phases, and you can always see where you are - Graphs and numbers show the results approaching the theoretical value as trials add up - If you go back during the final check, the app asks whether to leave the stage - Available in 73 languages, including English and Japanese (follows your device language) - No sign-in; start right away - Simulations work offline (the network is used only for ads) Great for: - Students learning probability and statistics - Anyone curious about the gap between intuition and mathematics - Teachers looking for classroom material - Anyone who wants to truly understand why the answer is what it is Price and purchases: - Price: Free - In-app purchases: None - Subscriptions: None - Ads: Banner ads by Pangle at the bottom of the screen, and a full-screen (interstitial) ad may be shown when you clear a stage - Ads are personalized only if you allow tracking. You can turn this off in "About this app" > "Ad settings" The "-raku" series of educational apps (selection): - SUUGAKU - Mathematics - BUTURAKU - Mechanics - DENRAKU - Electromagnetism - HARAKU - Waves - NETURAKU - Thermodynamics - KORAKU - Optics - RYURAKU - Fluid dynamics - KAKURAKU - Probability

Screenshots

RayLab4 screens
KAKURAKU4 screens

Verdict

The call

The clearest difference is in-app purchases: KAKURAKU at none against RayLab's 10. RayLab's advantage is iOS requirement (11.0 vs 15.0). On price, update cadence, ads and device support 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

Both are free to download. RayLab sells 10 in-app purchases, starting at $3.99 per month. KAKURAKU asks for nothing beyond the download.

UpkeepUpdate frequency

RayLab ships an update every 6 weeks, KAKURAKU every 3 weeks. The most recent releases landed on October 23, 2026 and October 25, 2026 respectively.

Scorecard2 real differences · 8 level
RayLab versus KAKURAKU: the parameters behind the verdict, then further details
ParameterRayLabKAKURAKU
PriceFreeFree
Rating4.7 (67 ratings) — better—
Positive reviews75.0% of reviews—
Number of ratings67 — better—
Update frequencyEvery 6 weeksEvery 3 weeks — better
AdsYesYes
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS11.0 — better15.0
Further details — not scored
Size39 MB30 MB
Age rating4+4+
DeveloperKamyar GhandiFuji Bit Inc.

In-app purchases

10 purchases

RayLab

Subscriptions1
  • RayLab Pro Subscription7 Days trial$3.991 Month
One-time9
  • RayLab Pro UpgradeFree
  • Schott Glass Catalog$0.99
  • Custom Glass Editor$0.99
Show 6 more
  • Advanced Optical Elements$1.99
  • Source and Lens Arrays$1.99
  • Solver/Optimizer Module$3.99
  • 3D Modeling$4.99
  • RayLab Pro 2$19.99
  • RayLab Pro Bundle$19.99
None

KAKURAKU

No in-app purchases

Questions

Is RayLab free?
RayLab is free to download, with in-app purchases available.
Is KAKURAKU free?
KAKURAKU is free to download, with no in-app purchases.
Do RayLab or KAKURAKU have ads?
Both RayLab and KAKURAKU show ads.
Which is updated more often, RayLab or KAKURAKU?
RayLab ships an update every 6 weeks, and KAKURAKU every 3 weeks. Most recently, RayLab was updated on October 23, 2026 and KAKURAKU on October 25, 2026.

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