Physics Playgrounds vs HDLSim
Price, ratings, monetisation and update history for both apps, side by side ā with what reviewers say about each.
Physics Playgrounds
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Physics Playground is a hands-on science app with 102 interactive labs ā from pendulums and black holes to rainbows, magnets and melting ice. Every lab is a live simulation you control with your finger, or with your hand in the air, so you can see how the world works instead of just reading about it. THREE WAYS TO EXPLORE ⢠Explore ā pick any lab and start playing. ⢠Learning Journey ā follow a short story one step at a time: Things that move, Light and sound, Earth and space. ⢠Curiosity Lab ā ask your own science question by typing or speaking and get a short, friendly answer. Tap "Draw it!" for a picture, save pictures to Photos, or have the answer read aloud. 102 LABS How the World Works (44 labs): Colour Mixer, Rainbow Spinner, Heavy or Light?, Drop Zone, Slide Race, Bouncy Balls and many more everyday science experiments Mechanics: Simple Pendulum, Projectile Motion, Elastic Collision, Spring Oscillator, Inclined Plane, Pulley System, Circular Motion and more Waves and Sound: Wave Interference, Doppler Effect, Standing Waves, Resonance Studio Light and Optics: Light Refraction, Light Reflection, Light Polarization, Rainbow Maker Electricity and Magnetism: Electric Field, Capacitor Charging, Circuit City, Magnet Maze, Electromagnetic Induction, Tesla Coil Heat and Matter: Gas Particles, Entropy & Disorder, Tiny Heat Engine, Crystal Builder, Phase Changer Quantum and Nuclear: Double Slit, Photoelectric Effect, Quantum Tunnel, Radioactive Decay, Nuclear Fission, Nuclear Fusion, Half-Life Detective Space and Relativity: Orbital Mechanics, Black Hole, Exoplanet Hunter, Relativity Rocket, Gravity Lens Earth and Energy: Tectonic Plates, Weather Balloon, Solar Grid, Wind Tunnel Fluids: Fluid Flow, Buoyancy, Vortex Lab HOW IT WORKS Touch the canvas to grab and interact with the simulation ā there is no right or wrong way to explore. Adjust variables like gravity, mass, length and velocity with the built-in sliders and watch the results change instantly. For a hands-free experience, turn on the camera and control labs with your hand in the air. Hand tracking runs on your device ā no images or video are stored or sent anywhere. CHALLENGES Every lab has a challenge that teaches the key idea behind it. Complete it to earn a star and track your progress across all 102 labs on the progress screen. REAL PHYSICS LAWS The simulations are built on real physics equations, and the app shows the governing laws so you can connect what you see to real formulas. ABOUT CURIOSITY LAB Answers and pictures are created by AI (Google's Gemini models) for learning and fun, and can sometimes be wrong. Every answer has a Report button, and questions are limited each day. Curiosity Lab asks for your permission before it shares a question with Google Gemini, and you can turn this off at any time in Privacy choices. WHO IS IT FOR Students, teachers and anyone curious about how the physics world works ā from first questions to university physics. It makes an excellent companion to classroom learning, and no prior knowledge is needed. PRIVACY Play as a guest ā no name or email needed. A grown-up can choose to sign in with Apple or Google to keep progress across devices, and can delete the account in the app at any time. You decide whether to share usage analytics. Camera processing happens entirely on your device. Privacy policy: https://physics-playground-24c5e.web.app/privacy Terms: https://physics-playground-24c5e.web.app/terms
HDLSim
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HDLSim is a digital electronics lab on your iPhone. Write Verilog, compile it for the EPM240 CPLD and watch it run on a virtual development board, with a 2D schematic and a 3D breadboard. WHAT YOU CAN DO ⢠Verilog editor with compilation and error messages. ⢠EPM240 CPLD simulator: load your design and test its inputs and outputs on the board. ⢠2D schematic: place components, wire them and simulate the circuit. ⢠Boolean equation compiler: truth table, Karnaugh map, minimum form and a gate circuit built with chips. ⢠Step-by-step guided lessons. ⢠3D bench and breadboard: the same circuit built in 3D, with wires, resistors, LEDs and more. ⢠Guided labs: Ohm's law, dividers, diodes and rectifiers, transistors, op-amps, logic gates, adder, latch, 555 timer and 7-segment display. ⢠Your projects are stored on your iPhone. PLANS ⢠Free: Verilog editor, CPLD simulator, 2D schematic and 3D bench, designs and labs with up to 7 breadboard components on the 170, 400 or 830-point board the circuit needs, and boolean equations of up to 4 inputs and 1 output (the circuit it builds does not count toward the 7-component limit while unedited). Includes ads. ⢠Pro: everything in Free with no ads, designs with more than 7 components, every lab in the catalog and equations of up to 6 inputs and 6 outputs. Pro is an auto-renewing subscription, monthly or yearly, at the price shown in the app. Payment is charged to your Apple ID when you confirm the purchase. The subscription renews automatically unless you cancel it at least 24 hours before the end of the current period. Manage or cancel it in Settings > your name > Subscriptions. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy: https://hdlsim.web.app/privacy.html
Screenshots
Verdict
The clearest difference is in-app purchases: Physics Playgrounds at none against HDLSim's 2. HDLSim's advantage is update cadence (every 4 days vs every 3 months). On price, ads, device support and iOS requirement there is nothing between them.
Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS
Both are free to download. HDLSim sells 2 in-app purchases, starting at $2.00 per month. Physics Playgrounds asks for nothing beyond the download.
Physics Playgrounds ships an update every 3 months, HDLSim every 4 days. The most recent releases landed on November 9, 2026 and November 13, 2026 respectively.
| Parameter | Physics Playgrounds | HDLSim |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 3 months | Every 4 days ā better |
| Ads | No | No |
| In-app purchases | No ā better | Yes |
| Devices | iPhone, iPad, iPod ā better | iPhone, iPod |
| Requires iOS | 15.0 | 15.0 |
| Further details ā not scored | ||
| Size | 37 MB | 15 MB |
| Age rating | 12+ | 12+ |
| Developer | KheniTech | Julio Francisco Reyes Gonzalez |
In-app purchases
Physics Playgrounds
No in-app purchases
HDLSim
- HDLSim Pro Monthly$2.001 Month
- HDLSim Pro Annual$20.001 Year
Questions
Is Physics Playgrounds free?
Is HDLSim free?
Do Physics Playgrounds or HDLSim have ads?
Which is updated more often, Physics Playgrounds or HDLSim?
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