Supported Features
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VoiceOver
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Voice Control
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Dark Interface
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Differentiate Without Color Alone
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Sufficient Contrast
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Reduced Motion
Unlimited Algorithms
Step through, backward too
Only for Mac
$2.99
Mac
Pick a procedure, give it input, and watch every comparison and every write as it happens. Step forward, step backward exactly, inspect the invariant, and follow every claim to its source.
DOZENS OF PROCEDURES, NOT CANNED ANIMATIONS
Every major family is here: sorting and selection, graphs, strings, geometry, numbers, search trees, compression, search, heaps, hash tables, dynamic programming, chance and streams, and union-find.
Each run is recorded by the procedure itself. The picture reads that record rather than replaying a separate animation that can drift away from the code.
A purpose-built view for whatever structure is at hand: arrays, trees, graphs, tables, text tapes, points, FFT butterflies, and skip-list levels.
Open the code pane beside the stage and keep the active line, the state, and the explanation together.
CONTROL EVERY STEP
Forward and backward. Every change carries the information needed to undo it, so reverse stepping is exact rather than a second run played in reverse.
Scrub the complete run, change the speed, or break on the next comparison, write, frame, or invariant failure.
Watch the cost as you go: comparisons, swaps, writes, reads, extra memory, and depth, all updating with the current step.
Predict what happens next. Pause before a comparison, call the result, and let the run answer.
ASK THE ALGORITHM TO PROVE ITSELF
Every procedure states an invariant and checks it throughout the run, including the moments when a repair such as a tree rotation is halfway done.
The catalogue explains what the procedure is for, how this implementation works, what it costs, and when it is the wrong tool.
Claims name their sources. Open the original paper, the textbook lineage, or the specification directly from the explanation.
Counterexample inputs make failures visible, including what happens when an algorithm's assumptions are deliberately broken.
CHOOSE THE QUESTION
Start from designed input shapes, reroll the same shape, change its size, or type the data yourself.
For compatible procedures, search for an input that drives the worst case instead of merely describing one.
Race compatible procedures on the same input. Both sides advance on a shared comparison clock, so the comparison stays honest.
ONE PURCHASE, EVERY DEVICE
One purchase covers Mac, iPhone, and iPad. No account, no subscription, no in-app purchases, no ads, no analytics, and no tracking. The catalogue and every run work offline.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Some performance and user interface improvements.
The developer, The Virtually Unlimited Corp, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
The developer indicated that this app supports the following accessibility features. Learn More
Information
- Seller
- The Virtually Unlimited Corp
- Size
- 2.3 MB
- Category
- Education
- Compatibility
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
- Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
- Mac
- Age Rating
4+
- 4+
- Copyright
- © 2026 The Virtually Unlimited Corp
