DLD vs HDLSim
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
DLD
Design and simulate digital logic circuits in real-time. Build complex systems with a variety of components, visualize signal flow, and generate truth tables and Boolean equations. Ideal for students and enthusiasts learning digital logic.
- 28 digital logic components
- Real-time signal animation
- Automatic truth table generation
- Boolean equation output
- Offline circuit saving
- Interactive tutorial section
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DLD is a digital logic design and circuits workbench for your phone. Drop gates onto the bench, wire them together, flip a switch, and watch the signal travel through the circuit in real time. Built for students working through a digital logic design course — and for anyone who wants to see Boolean algebra actually do something. BUILD ANYTHING • 28 components: switches, clocks, Vcc and ground, every standard gate, tri-state buffers, multiplexers, flip-flops, displays and probes • Gates take 2 to 8 inputs — one wide NAND instead of three cascaded ones • Tap a component to reach its settings: input count, clock speed, colour • A work bench far bigger than the screen, with pan, zoom and fit-to-circuit SEE IT WORKING • Current animates along every live wire, so you can follow a signal • LEDs, LED bars, 7-segment and hex displays light up as the circuit runs • A school bell that rings for as long as it has current • Logic probes read out 1 or 0 anywhere you wire one UNDERSTAND IT • Boolean equations written out from whatever you have drawn • A full truth table generated from your circuit, ready to copy out • Conflicting drivers on a net are flagged rather than quietly wrong • A tutorial section covering every gate symbol and its truth table KEEP YOUR WORK • Save and reopen as many circuits as you like • Undo and redo everything • Recolour wires, lamps and blocks however you want to read them COMPONENTS Switch · Clock · Vcc · GND · AND · OR · NOT · NAND · NOR · XOR · XNOR · Buffer · Tri-state buffer · Tri-state NOT · MUX · DEMUX · D flip-flop · T flip-flop · JK flip-flop · Virtual links · LED · LED bar · 7-segment · Hex display · Bell · Probe · Label PRIVATE BY DEFAULT No account. No sign-in. No analytics. No ads. Nothing leaves your device — your circuits are saved on the phone and nowhere else. The app works with no network connection at all.
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: DLD at none against HDLSim's 2. HDLSim's advantage is update cadence (every 4 days vs every 5 weeks). On price, ads, device support and iOS requirement 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
Both are free to download. HDLSim sells 2 in-app purchases, starting at $2.00 per month. DLD asks for nothing beyond the download.
DLD ships an update every 5 weeks, HDLSim every 4 days. Both last shipped on November 13, 2026.
| Parameter | DLD | HDLSim |
|---|---|---|
| Price | Free | Free |
| Rating | 4.5 (2 ratings) — better | — |
| Number of ratings | 2 — better | — |
| Update frequency | Every 5 weeks | Every 4 days — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 14.0 — better | 15.0 |
| Further details — not scored | ||
| Size | 19 MB | 15 MB |
| Age rating | 4+ | 12+ |
| Developer | Muhammad Rafhan | Julio Francisco Reyes Gonzalez |
In-app purchases
DLD
No in-app purchases
HDLSim
- HDLSim Pro Monthly$2.001 Month
- HDLSim Pro Annual$20.001 Year








