# Gerber Viewer

> Drop a fab .zip — RS-274X / Gerber X2 plus Excellon drill files, the kind KiCad and Altium spit out. The viewer detects which layer is which, lets you toggle, reorder, snap-to-pad measure in millimetres at the file's native resolution, click any trace to pin its width as a persistent annotation, click an aperture row to glow every flash of that D-code, and run DRC checks against fab-house presets. Renders in WebGL; viewport and visible layers encode into the URL fragment for sharing. Files never upload — handy when the fab archive is under NDA or you'd rather skip online-gerber-viewer.com's server round-trip.


Live tool: https://lofttools.com/tools/open-tools/gerber-viewer

Category: Open Anything


## What it does

- RS-274X parser with full Gerber X2 attribute support
- Excellon and XNC drill files auto-detected
- .zip / .tar / .tar.gz / .tgz archive auto-extract
- Loose .gbr / .drl / .gtl / .gbl / .gts / .gbs / .gko / .gm1 files accepted
- Per-layer toggle, reorder, color, and opacity controls
- Snap-to-pad measurement at the file's native coordinate resolution (typically 0.1 µm)
- Trace-width probe shows the conductor width under the cursor — click any trace in inspect mode to pin a persistent dimension annotation
- Aperture highlight — click any D-code row in the aperture table to glow every flash of that tool on the selected layer
- DRC checks with preset rule packs (fab-standard, hobbyist, JLCPCB / PCBWay) and per-rule overrides; violations group into an error explorer that recenters the viewport on click
- X2 netlist surfaced from %TO.N attributes — click a net to highlight every connected pad and stroke across copper layers
- WebGL renderer with stencil-based polarity for clean overlapping fills
- Viewport, layer visibility, color, and opacity encode into the URL fragment for sharing
- PNG, SVG, and DXF export
- Soldermask, silkscreen, copper, paste, drill, and outline layers rendered with realistic colors
- Bottom-side default-hidden until toggled (avoids overlap clutter on first load)
- Flex / rigid-flex board detection with stackup pane (auto bend-radius math per IPC-2223)
- Aperture macro support including primitive 7 (thermal) edge cases
- Pick-and-place CSV overlay (KiCad .pos, JLCPCB CPL, Altium PnP auto-detected)
- Drag-and-drop or file-picker input
- Works offline after the first visit (PWA cache)

## How it works

1. **Drop your fab archive** — Drag a .zip / .tar / .tar.gz of your fab output, or loose .gbr / .drl files. The viewer detects which layer is which automatically.
2. **Toggle layers** — Click any layer in the side panel to show or hide. Reorder for diff inspection. Adjust per-layer color and opacity.
3. **Measure** — Switch to measure mode. Click two points — distance snaps to pad centers and trace centerlines. Trace-width probe shows the conductor width under the cursor.
4. **Share or export** — Copy the URL — viewport and visible layers are encoded in the fragment. Or export PNG / SVG / DXF.

## FAQ

### What Gerber formats does this support?

RS-274X (extended Gerber) and Gerber X2 attributes. Excellon and XNC drill files are auto-detected. Older RS-274D (no embedded apertures) is not supported.

### What archive formats can I drop?

.zip, .tar, .tar.gz, and .tgz. Loose .gbr / .drl / .gtl / .gbl files are also accepted.

### Can it open ODB++ or IPC-2581?

Not yet. Gerber RS-274X / X2 plus Excellon are the MVP. ODB++ and IPC-2581 are on the roadmap.

### How accurate are the measurements?

Distances are computed in the file's native coordinate system (typically millimeters at 0.1 µm resolution). Pad-center snap is geometric (centroid of the aperture flash).

### Is Gerber a trademark?

Yes — Gerber is a registered trademark of Ucamco NV. Loft Tools is an independent third-party viewer and is not affiliated with or endorsed by Ucamco.

## How Loft Gerber Viewer compares

| Tool | Install needed | Files uploaded | RS-274X | Excellon | Measurement | URL snapshot | Cost |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Loft Gerber Viewer | No | No (in-browser) | Yes (X2 attrs) | Yes | Snap-to-pad | Yes | Free |
| gerbv (Linux native) | Yes | N/A | Yes | Yes | Limited | No | Free |
| KiCad GerbView | Yes (KiCad install) | N/A | Yes | Yes | Yes | No | Free |
| online-gerber-viewer.com | No | Yes (server upload) | Yes | Yes | No | No | Free |
| Tracespace | No | Yes (server upload) | Yes | Yes | No | No | Free |
| ZofzPCB (3D) | Yes (Windows) | N/A | Yes | Yes | No | No | Free |

_Verified 2026-05. Native PCB CAD suites (Altium, EAGLE, Mentor) are not listed — they include their own Gerber inspector but require a paid licence to launch.
_

## Privacy

This tool runs entirely in the browser. Files are not uploaded to a server. They never leave the user's device.

## More

- All tools: https://lofttools.com/tools
- Category: https://lofttools.com/tools/open-tools
- LLM index: https://lofttools.com/llms.txt