| Data | Common filename extensions | Review purpose |
|---|---|---|
| Copper | GTL · GBL · GBR | Top and bottom patterns and missing areas |
| Silkscreen, mask and outline | GTO · GBO · GTS · GBS · GKO · GM1 | Distinguish text, mask and board outline. Naming conventions vary by authoring tool. |
| Drills | DRL · XLN · EXC | Hole locations and sizes, and matching Gerber units and origin |
| PCB ZIP | A bundle of fabrication layers and drill files | Required fabrication files and decompressed-data limits |
Review layers and drills in order
- Ask for the export revision and file list. Do not mix copper and drills from different revisions.
- Use basic viewing to select supported layers individually and inspect the outline and pattern.
- Compare drill units, origin and holes with the original CAM or KiCad Gerber Viewer.
- Supported overlays require Pro. If layers disagree, check origin, units and mirror settings in the authoring tool.
Why can a small ZIP fail to open?
Compressed size differs from expanded data size. The limits are 16 MiB input, 16 MiB expanded data, 64 archive entries and 16 layers. Each Gerber layer is limited to 50,000 commands.
Request just the required Gerber and Excellon fabrication files rather than a complete KiCad project and unrelated documents. Aperture macros and step-repeat are unsupported; use the original CAM tool for those files.
A layer name does not establish its coordinates
GTL and GBL names are clues, not guarantees about coordinates or mirroring. Ask the author about bottom-layer viewing direction, drill units and export origin. Do not modify source fabrication files solely to match a browser preview.
Viewing is different from fabrication acceptance
A web preview does not check manufacturability, DRC, electrical connectivity or manufacturing tolerances. Complete fabrication review in the original KiCad or CAM tool and against the manufacturer requirements. Standalone KiCad preview and Gerber fabrication viewing use different inputs.
Open the relevant viewer or workflow
Basic viewing: one file per day in the same browser, without signup. File, geometry and device limits apply to Free and Pro. Pro checkout is being prepared. The viewer and interactive demo interface is currently Korean.