Copper help
Copper has four tools, on the tabs at the top. Signal integrity simulates nets with IBIS drivers and receivers, transmission lines and terminations, live as you change them. Stackup describes the board's layers and works out the impedance and delay of traces from their geometry, with a picture of their field. S-parameters opens measured or simulated networks to compare them, check their quality, look at them in the time domain and transform them. Power looks at a supply rail's impedance and its decoupling. Everything runs in your browser.
- Signal integrity: Nets with IBIS drivers and receivers, transmission lines and terminations, simulated live as you change them: the topologies and your own schematics, the scope, the measurements and the analysis views.
- Stackup: The board’s layers, and the impedance, delay and loss of a trace or a pair worked out from its geometry by a field solver, with a picture of the field. Signal integrity uses this board for its vias and for every line set by geometry.
- S-parameters: Measured or simulated networks (Touchstone, CITIfile or CSV): compare them, check their quality, look at them in the time domain and transform them.
- Power: A supply rail’s impedance from the regulator to the die against its target, the capacitors that bring it down, the planes’ resonances, and the droop when the load steps.
Lessons
Lessons in the top bar opens short guided lessons on the live tools. Each step sets the net up, points at what to look at, and ticks off what it asks you to try; the scope keeps running, so you can change anything along the way. A lesson changes the topology settings (never your schematic designs); Put my settings back restores them. An interrupted lesson comes back where you left it.
- A tour of Copper: every tool and panel, one stop each (offered once on a first visit).
- Reflections and terminations: why a fast edge rings on a line, and four ways to stop it.
- Seeing the waves: the forward and backward waves along a line, the lattice diagram, and TDR.
- Crosstalk: near and far end, spacing, and microstrip against stripline.
- Eyes, jitter and bit rate: what closes an eye.
- Loss and the stackup: impedance and loss from the board's layers and copper.
- Vias and stubs: the stub resonance, and backdrilling.
- Differential pairs: the common mode, and terminating a pair.
- Branched nets and stubs: a bus with several receivers, stub length, and where the termination goes.
- IBIS models, corners and timing: what a model holds, slow and fast corners, flight time.
- The stackup and impedance planning: a trace's impedance from its cross-section, finding widths and spacings.
- Decoupling a power rail: target impedance, resonances, anti-resonances and the droop.
- Reading S-parameters: insertion and return loss, from a net to a Touchstone file and back.
- Drawing your own net: parts, wires, probes, notes and tidying the drawing.
Your library
Every set of built-in values can be kept as your own: ferrite beads and connectors (their Preset choice), capacitor types (in the Power tab), stackups and copper foils (in the Stackup tab). Save as mine asks for a name; the item then appears under Your library in the same choice, in any design. Library in the top bar lists everything you saved, removes items, and saves the whole library to a file or adds one from a file, to move it to another browser. A design keeps its own copy of the values it uses, so removing an item changes no design, and a design file opened elsewhere needs no library.
Themes, windows and screen sizes
Lengths: the mm / mil menu in the top bar shows every length in millimetres or in mils (an inch
or more in inches). Either can be typed anywhere: 0.1 mm, 4 mil, 2 in.
The menu at the right of the top bar chooses the colour theme: Auto follows your system's light or dark setting; Light, Dark, Paper, Ocean, Midnight, Graphite, High contrast, three after the app's own metal (Copper, Gold and Patina, the green of old copper), and two old-school looks, Classic desktop and Retro blue. The plots' colours are checked against each theme's background, so the traces stay apart for colour-blind eyes too.
On a wide screen (1500 pixels and up) the signal-integrity tool puts the diagram or schematic and the scope on the left and the measurements and the analysis on the right, the Power tab the impedance on the left and the droop and the plane resonances on the right, and the Stackup tab the cross-section across the screen under the trace and its results. The plots then grow until each column reaches the bottom of the window, so on a full-HD screen a whole tool fits without scrolling. In a narrow column the measurements show each receiver as a small grid of labelled values. On a narrower screen the cards stack; on a small one each tool's settings move into a drawer: Settings in the top bar opens and closes it.
Windows: each card (the scope, the measurements, the analysis, the drawing, the plots of the Power and Stackup tabs) stays in its place; what you set is its size. Drag the short bar on a card's bottom edge to set its height (double-click it for the card's own height again); the other cards in its column still grow to fill the window. ? in a card's top right corner opens the help on it; ▾ folds it to its title, which gives its room to the rest, and ↺ (shown once a card is folded or sized) puts that card back. Drag the bar between the columns to set their widths, and the sidebar's right edge to set its width. The sizes are kept in this browser for each tool; Reset ▾ in the top bar, Window layout, puts every card back to its own size, in every tool.
Keys and mouse
| Ctrl+Z | Undo |
|---|---|
| Ctrl+Shift+Z, Ctrl+Y | Redo |
| Click a plot | Make it active; place a marker (or a limit point while drawing) |
| Drag in a plot | Zoom to the box |
| Shift+drag, or drag with the right button | Pan the plot |
| Ctrl+wheel over a plot | Zoom the frequency (or time) axis around the pointer |
| Double-click a plot, or Fit (on its bar, or in its corner while zoomed) | Show all of it again |
| Shift+click a term | Add or remove it for all open files |
Privacy
Your files never leave your computer: they are read and computed in the browser, and nothing is uploaded. There is
no tracking. What the page remembers is kept in this browser's own storage for this site. In the S-parameter tool
you can clear it with Forget all or by turning remembering off; designs are deleted from their list
(Designs in this browser). A design link holds the design after the #, which is not sent to the
server.
Reset ▾, Everything: start as new, removes everything Copper keeps in this browser (designs, your library, S-parameter files, settings, lessons and window sizes) and opens it as on a first visit, after asking. Save what you want to keep first. With Copper open in another tab, that tab lets go of its stored data too.
When it starts on the web, the app asks its own site for a short signed note that it may run at that address, then fetches each tool’s code from the site the first time you open the tool. These requests carry nothing about you and nothing of your work: your designs and files are never sent. Copper therefore needs its site to start.
Version history
1.0.0 (2026-11-08)
The first release.