Like hneemann's Digital, but in your browser
Digital is a free, open-source (GPL-3.0) digital logic simulator by Helmut Neemann (hneemann on GitHub), started in 2016 by a long-time Logisim user and designed for teaching. It is a Java desktop application that needs a Java runtime (JRE 8 or newer). If that is what brought you here, digiwleea is a free, in-browser alternative with a different angle: you build a computer from the transistor up.
What Digital is good at
Digital is excellent and very capable: measurement graphs of signal states, test cases you write and run to verify a design, analysis and synthesis of combinational and sequential circuits, a finite state machine editor, a library of common 74xx chips, export to VHDL and Verilog, and direct support for FPGA boards such as the BASYS3. If you want a serious desktop tool for digital design, it is one of the best free options.
How digiwleea is different
digiwleea needs no Java and no download: it runs in any modern browser, including on a Chromebook or a phone. It is also built around learning rather than design work. You start one layer lower, building NOT, NAND and the other gates from individual CMOS transistors, then follow a guided 40+ level course that composes them into adders, latches, registers, RAM and control logic up to a working 8-bit CPU, with live truth-table checks, theory lessons and an AI tutor (Wleea). Pick Digital for HDL export, FPGA work and test-driven design; pick digiwleea to learn how the whole machine works from the bottom up.
| Digital | digiwleea | |
|---|---|---|
| Runs in | Java desktop app (JRE 8+) | The browser, nothing to install |
| Smallest building block | Gates, 74xx chips, components | CMOS transistors (build the gates too) |
| VHDL / Verilog export, FPGA | Yes | No |
| Guided course to a CPU | No (a design tool) | Yes, 40+ levels |
| AI tutor | No | Yes (Wleea) |
| Price / license | Free, open source (GPL-3.0) | Free lab and Act I; Premium for the full course |
No sign-up is needed to start: open the lab and place your first transistor, or read the free theory course. The account (and the AI tutor) are optional.
See for yourself: build a logic gate from transistors in the simulator, then follow the path from sand to an 8-bit CPU.
Open the digiwleea lab →Frequently asked
Is digiwleea a good Digital alternative?
Yes, if you want to understand digital logic from the ground up. digiwleea is a free, in-browser simulator with a guided 40+ level course where you build every gate from CMOS transistors and work up to a real 8-bit CPU, with an AI tutor to help.
Is digiwleea free?
The sandbox lab and the first act of the course are free and need no sign-up. An optional account adds the AI tutor and cross-device sync; the full course and expanded AI tutoring are included in the monthly or annual Premium subscription.
Do I need to install anything?
No. digiwleea runs entirely in your browser, on desktop or mobile, and works offline once loaded.