Icestudio alternative: draw and test logic with no board

Icestudio is a free, open-source (GPL-2.0) visual editor for open-source FPGA boards from the FPGAwars community, focused on newcomers to FPGAs. Its README sums it up in three steps: draw your circuit, upload it to your FPGA board, done. It runs on Linux, macOS and Windows, works with boards such as the Alhambra II and the iCEBreaker, and its example collections go as far as a RISC-V CPU, a Z80 and the Hack CPU from nand2tetris. Its latest tagged release is v0.12 (June 21, 2024). Icestudio puts the circuit you draw onto a real FPGA; digiwleea simulates the circuit you draw in the browser, starting from the transistor.

What Icestudio is good at

The friendliest way onto a real open-source FPGA: blocks and wires instead of a page of HDL, then one click to load the design onto a board and watch real LEDs blink. Seeing a design run on hardware is a big motivation, and the community collections give you a lot to start from. (digiwleea is an independent project, not affiliated with FPGAwars.)

How digiwleea is different

digiwleea needs no board and no install: it runs in the browser and simulates every wire, so you can see why a circuit works, not only that it does. You build NOT and NAND from CMOS transistors, then adders, multiplexers, flip-flops, counters, registers, RAM and an 8-bit CPU that runs a stored program, through a 40+ level course where every part is checked against its truth table, with an AI tutor (Wleea). It does not program FPGAs. The two fit well: learn the parts here, then build them on a board in Icestudio. If the Hack CPU interests you, see the nand2tetris comparison.

	Icestudio	digiwleea
Purpose	Visual design for open-source FPGA boards	Learning digital logic, transistor to CPU
Runs the design on	A real FPGA board	A simulator in the browser
Starting point	Ready-made blocks and community collections	Single transistors as switches
Runs on	Linux, macOS, Windows	Any modern browser
Price	Free, GPL-2.0 (a board to buy)	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.

More comparisons: HDL, FPGA and chip design tools

Yosys alternative Microwind alternative Lattice Diamond alternative IRSIM alternative Quartus Prime Lite alternative Magic VLSI vs Electric VLSI Vivado alternative Cadence Virtuoso alternative Icarus Verilog vs Verilator vs GHDL KLayout alternative ModelSim alternative Tiny Tapeout

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

What is Icestudio?

A free, open-source visual editor for open-source FPGA boards: you draw a circuit from blocks and upload it to a board such as the Alhambra II or iCEBreaker. It runs on Linux, macOS and Windows.

Do I need an FPGA board for Icestudio?

To run a design on hardware, yes; uploading to a board is its main step. To learn and simulate logic with no hardware, a browser simulator such as digiwleea works.

Can you build a CPU in Icestudio?

Yes. Its example collections include a RISC-V CPU, a Z80 and the nand2tetris Hack CPU. In digiwleea you build a smaller 8-bit CPU yourself, from transistors up.