Verilog · SystemVerilog · VHDL
Learn digital design by writing it.
Practice HDL circuits from your first wire to production RTL — synchronous and asynchronous FIFOs, clock-domain-crossing synchronizers, valid/ready pipelines, and memory controllers. Everything compiles and simulates instantly, right in your browser.
Built to be better than a Verilog-only wiki.
Three languages, one judge
Solve the same circuit in Verilog, SystemVerilog, or VHDL — pick the HDL your course or job actually uses.
Simulation runs in your browser
No server queue, no waiting. Your code compiles and simulates locally the moment you hit Run.
Real feedback, not just pass/fail
See a signal-level waveform and diff against the expected output — understand why a test failed, not just that it did.
Beyond the classroom
A dedicated RTL Design Patterns track covers FIFOs, clock-domain crossing, handshaking, pipelines, and memories — the blocks you'll actually build on the job.
Pick a track
From your first assigned wire to clock-domain crossing you'll be asked about in an interview.
Getting Started
Your first modules — wiring, ports, and how a submission gets checked.
Hardware Language
The language fundamentals: wires, vectors, modules, procedural code.
Circuits
Combinational and sequential building blocks, from gates to state machines.
Verification
Reading waveforms and writing the testbenches that drive them.
RTL Design Patterns
Production-grade blocks you will actually build on the job — not in any textbook problem set.
Reference while you learn
Build good habits. Review the basics.
Use language-specific guides for clean, reliable RTL, or check an overview when you need a quick theory refresher.