I'm learning.
Start at the AND gate. Finish by running your own assembly on a CPU you built. Every step narrated, no install.
- Free sandbox, no card required
- SimCast lessons in your language
- Verifiable certificate of mastery
Browser-native digital logic, taught and built
From a single AND gate to a working 8-bit CPU.
DigiSim is a real-time digital logic simulator and an interactive teaching platform. 60 components, narrated lessons in 7 languages, and shareable interactive circuits — built for students, professors, and engineers who want the real thing in the browser.
60 components
7 languages
∞ circuits saved locally
0 subscriptions
Three doors. One workshop.
Whether you're catching up on logic gates or wiring a control unit, DigiSim meets you where you are.
I'm teaching.
Real interactive lessons your students can run in the browser — no install, no account. The Pro tier unlocks the SimCast author tool so you can record your own walkthroughs.
- 21 free lessons cover intro-CS curriculum
- Author lessons with Professor Mode (Pro tier)
- Academic email gets 50% off automatically
I'm building.
Real event-driven simulation with propagation delay, tri-state contention, and 8-channel oscilloscopes. Save anywhere.
- 60 components incl. RAM, ROM, ALU
- Custom 8-bit CPUs with assembly
- Local .digi files, your data
SimCast · Professor Mode
Lessons that don't just play. They teach.
Press play and a finished circuit comes alive. The lesson highlights one component, narrates the idea, then pans the camera to the next. Pause anywhere — every signal is still probeable, because it's still a simulator.
English中文日本語Español한국어DeutschFrançais
Sixty components. One complete CPU stack.
From the AND gate you learned in week one, to the program counter, instruction register, and 8-bit ALU that run your own assembly. Nothing simulated halfway.
Input
Switch
Input
Clock
Input
Constant
Input
Constant Zero
Input
Assembly Loader
Gate
AND
Gate
OR
Gate
NOT
Gate
NAND
Gate
NOR
Gate
XOR
Gate
XNOR
Gate
Buffer
Gate
Tri-State Buffer
Gate
8-bit Tri-State
Mux
MUX 2:1
Mux
MUX 4:1
Mux
MUX 8:1
Demux
DEMUX 1:2
Demux
DEMUX 1:4
Demux
DEMUX 1:8
Decoder
Decoder
Decoder
Decoder 3:8
Encoder
Encoder
Encoder
Encoder 8:3
Arith
Half Adder
Arith
Full Adder
Arith
Adder
Arith
8-bit Adder
Arith
Comparator
Arith
8-bit Comparator
Arith
ALU
Arith
8-bit ALU
Latch
SR Latch
Latch
D Latch
Flip-Flop
D Flip-Flop
Flip-Flop
JK Flip-Flop
Flip-Flop
T Flip-Flop
Register
Register
Register
Shift Register
Register
8-bit Register
Register
8-bit Shift Reg
Counter
Counter
Counter
8-bit Counter
Memory
RAM
Memory
ROM
CPU
Program Counter
CPU
Instruction Reg
CPU
Control Unit
CPU
MAR
CPU
8-bit Data Bus
CPU
Flags Register
CPU
Accumulator
Display
Output Light
Display
Digit Display
Display
7-Segment
Display
Text
Display
16×16 Pixel Screen
Scope
Oscilloscope
Scope
Oscilloscope ×8
CPU and memory components arrive on the Fundamental tier. See pricing →
A path that ends where real computers begin.
Six rungs from a single gate to running your own machine code. Built around the same syllabus as a university Computer Organization course.
01
Logic Gates Beginner
Boolean algebra you can poke at. Build the truth table by hand, then watch it light up in silicon.
Examples: AND · NOR · XOR · De Morgan demo
02
Combinational Circuits Beginner
Wire gates together to do something useful — pick signals, decode addresses, compare numbers.
Examples: Half adder · 2-to-4 decoder · 4-bit comparator
03
Sequential & Memory Intermediate
Logic that remembers. The clock arrives, hazards become real, and you meet your first state machine.
Examples: D flip-flop · 4-bit shift register · Johnson counter
04
Arithmetic & ALU Intermediate
Carry-lookahead, two's complement, an ALU that knows the difference between ADD and AND.
Examples: Ripple-carry adder · Booth multiplier · 8-bit ALU
05
Memory & Bus Advanced
RAM, ROM, an address bus, a data bus. The pieces start to look like the diagrams in your textbook.
Examples: 16×8 RAM · Tri-state bus · Address decoder
06
A working 8-bit CPU Advanced
Program counter, instruction register, control unit, flags. Write assembly, load it, watch fetch-decode-execute.
Examples: LDA / STA / JMP · 16×16 pixel output · Fibonacci on iron
Used in courses at
MIT
Stanford
Cambridge
Imperial
ETH Zürich
TU Munich
Caltech
Waterloo
NUS
U. of Tokyo
KAIST
Melbourne
Buy it once. Own your stack.
No subscriptions. No recurring fees. Upgrade tiers later — just pay the difference.
Fundamental
$16
one-time purchase - 14 components
- 20 interactive lessons
- Upgrade anytime, pay the difference
Professional
$32
one-time purchase - 39 components
- 51 interactive lessons
- Upgrade anytime, pay the difference
Academic discount: sign up with a .edu / .ac.uk email — discount applied automatically at checkout. Secure payment by Stripe.
Open the simulator. Build the first thing.
You don't need an account to start. You don't need to install anything. Just pick a door.