Web App
The nexsim web app runs entirely in your browser — no installation required. Open app.nexsim.dev to get started.
Walkthrough
Section titled “Walkthrough”1. Load your files
Section titled “1. Load your files”Click the folder icon in the sidebar or drag .vhd files into the window. Each file appears in the file list with a status badge:
- Pending (amber) — queued for compilation
- Compiled (green) — parsed and validated successfully
- Error (red) — contains a syntax or type error
Files are compiled automatically as they’re loaded.
2. Pick a top entity
Section titled “2. Pick a top entity”Once files compile, the entity picker dropdown appears. Select the testbench entity you want to simulate (e.g., mux_2x1_tb).
3. Simulate
Section titled “3. Simulate”Set the run time in nanoseconds and click Simulate. The status indicator animates while the simulation runs.
When it completes, signals appear in the sidebar under the signal tree.
4. View waveforms
Section titled “4. View waveforms”Check the boxes next to signals to add them to the waveform canvas. Uncheck to remove.
Signals are grouped hierarchically — you can expand/collapse groups and select entire groups at once.
5. Interact with waveforms
Section titled “5. Interact with waveforms”- Click on the waveform to place a cursor and read values at that time
- Scroll to zoom in and out
- Drag to pan across the timeline
- Change the time unit (ns / us / ms) to match your simulation scale
See Waveform Viewer for the full controls reference.
Importing VCD files
Section titled “Importing VCD files”You can view existing VCD waveforms without running a simulation. Just drag a .vcd file into the app — the parser extracts signal definitions and value changes automatically.
Resetting
Section titled “Resetting”Use the toolbar buttons at the top of the sidebar:
- Reset (refresh icon) — clear the current simulation state
- Clear Waveforms (trash icon) — remove all signals from the waveform view
Limitations
Section titled “Limitations”The web app has the same feature support as the CLI. See Known Limitations for details on what VHDL features are not yet supported.