Draw the circuit or write the Verilog. Either way you get an answer in about a second.
Hardware you can run,
not hardware you can memorise.
Codiode teaches Digital Electronics, Verilog, SystemVerilog and RTL design by having you build the thing first, then showing you whether it really works.
Your work actually runs
Every submission is compiled and simulated on a real engine. There is no answer key sitting underneath it.
Draw it or write it
Some problems want gates and wires. Others want Verilog. You can switch between the two on the same problem.
An answer in about a second
Nothing to install and nothing to wait for. Your result comes back while you are still looking at the screen.
More than 1,300 problems
They start at a single gate and end at pipelined datapaths, building up one step at a time.
See what your design did
You get the waveform and the truth table on every run, so you can find the exact edge that broke it.
Built around your syllabus
It follows what ECE and EE students study, then keeps going into GATE, interviews and real RTL work.
- SubmitYour circuit or your HDL leaves the browser.
- CompileIt is built on our servers and checked for real errors.
- SimulateIt runs against that problem's own test bench.
- VerdictWaveform, truth table and the vector that failed.
Start at one logic gate. Finish at a synthesis report.
Logic Gates
Arithmetic
Combinational Blocks
Latches & Flip-Flops
Counters
Shift Registers
Timing & Clocking
Registers & BusesBuilt on the canvas. Place the gates, wire them together, watch every node settle.Written in the editor, then compiled and run against that problem’s own test bench.
Start at one logic gate. Finish at a synthesis report.
Logic GatesArithmeticCombinational BlocksLatches & Flip-FlopsCountersShift RegistersTiming & ClockingRegisters & BusesPlace the gates, wire them together, watch every node settle.Write the module, then run it against that problem’s own test bench.
Start at one logic gate. Finish at a synthesis report.
On the canvas
Place the gates, wire them together, watch every node settle.
AND, OR, XOR and NAND. Wire the primitives up and watch every output settle.
Half and full adders, subtractors, comparators and the datapath of an ALU.
Multiplexers, decoders, encoders and tri-state buffers.
SR, D and JK. The engine resolves the cross-coupled feedback for you.
Ripple, synchronous and mod-N, stepped one clock edge at a time.
SISO, SIPO, PISO and universal, shifting on every tick.
Setup, hold and propagation delay, read straight off the waveform.
Register files, bus arbitration and the datapath built around them.
In the editor
Compiled and run against that problem's own test bench.
Port lists, parameters and your first synthesisable module.
Dataflow modelling with assign, ternaries and bit-select.
Clocked always blocks, resets and non-blocking assignment.
One-hot and binary encodings, Moore and Mealy outputs.
Arithmetic and logic units built as a single case statement.
Register files, single- and dual-port RAM, ROM initialisation.
Stage registers, hazards and the throughput you get in return.
Stimulus, self-checking assertions and $display output.
What really maps to hardware, and what quietly leaves you with a latch.
Build intuition before
you write a line of code.
A circuit canvas you build on by dragging. You can watch a signal travel through your design as it happens, with no syntax to fight and nothing to memorise first.
- Component library
- 60+ parts
- On every run
- Truth table
- Verdict
- About a second
Write real Verilog.
Verify in seconds.
A Verilog editor with the test benches already written, waveforms on every run and grading that happens on the spot. Everything your hardware course asks for, in the browser.
- Languages
- Verilog, SystemVerilog, VHDL
- On every run
- Waveform and synthesis report
- Verdict
- About a second
Frequently asked questions
Codiode is a place to learn Digital Electronics, Verilog, SystemVerilog and RTL design by actually simulating your work rather than answering quizzes. You write real code, build real circuits, and get your result back in about a second.
Verilog, SystemVerilog and VHDL in the RTL editor, and gates and wires on the LOGIX canvas. Many topics exist in both environments, so you can build a design first and then write the same thing in HDL.
Yes. You can sign up and start solving problems without paying. There is a Pro tier if you want detailed analytics, the premium skill tracks and priority access to contests.
Your Verilog or your circuit is compiled and simulated on our servers as soon as you submit, against that problem's own test bench rather than a stored answer. You get the waveform, the truth table and a pass or fail, usually within a second.
Engineering students in ECE, EE and CS, anyone preparing for GATE, people chasing a VLSI internship, and anyone who simply wants to learn digital design and HDL properly.
None at all. The beginner tracks start at basic logic gates and work up to FSM design and RTL coding one step at a time.
Yes. The problems are modelled on what VLSI companies actually ask, so working through them builds the skills a hiring manager is looking for.
No. There is no toolchain to set up and nothing to download. The compiler and the simulator run on our servers, so a browser is the whole requirement, though the canvas and the code editor both want a tablet-sized window or larger.
LeetCode is about software algorithms. Codiode is about hardware: digital logic, Verilog, SystemVerilog, circuit simulation and RTL. Think of it as the hardware engineer's version.
Ready to start building?
Thousands of students and engineers are already learning digital design here by building and running it.