Gerber files versus design source files
What an online Gerber viewer can and cannot tell you compared with viewing the KiCad project itself, and when each one matters.
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Gerbers are the output of a design: what the manufacturer images, etches and drills. The design source, such as a KiCad project, is the design itself: the schematic, the parts and the board as you laid it out. A Gerber viewer and a source viewer answer different questions, and knowing which one you need saves time.
What a Gerber viewer can tell you
- What will be built. The exact copper, mask, silkscreen and outline the fab will make, layer by layer.
- Whether the export is complete. Missing layers, unfilled pours, holes that don't line up, a broken outline. See the checklist.
- Sizes and spacing. With a measuring tool: board size, hole sizes, trace widths and clearances.
- Sometimes, nets and pads. Gerber X2 files can carry attributes that name the net or component pad behind an object, if the exporter wrote them.
What a Gerber viewer can't tell you
- The schematic. Which parts connect to which, and why.
- Component values and part numbers. A footprint's outline might be on the silkscreen; its value, tolerance and manufacturer part number aren't in the Gerbers.
- A bill of materials. You need the source, or a separate BOM file.
- Design intent. Whether a trace is too thin for its current, whether a net is meant to be there at all, which design rules were used. The Gerbers just show the result.
- What the board looks like assembled. No 3D models of components.
- What changed between revisions. Two sets of Gerbers can be compared as pictures, but not as design changes.
What viewing the KiCad project adds
Opening the project shows the schematic, the PCB with its nets, the parts, a 3D view and the BOM, all tied together. You can click a pad and see what it connects to, find a part on the schematic and on the board, and see the design as the designer saw it. Versions of a project can be compared as designs, not just as images.
When each matters
| Your job | What you need | Why |
|---|---|---|
| Checking an export before ordering bare boards | Gerber viewer | The fab builds from the Gerbers, so check the Gerbers. |
| Buying boards from someone else's files | Gerber viewer | You often only receive Gerbers; check they're complete and the size is right. |
| Ordering assembly | Both | Assembly needs the BOM and placement data that come from the source. |
| Reviewing a colleague's design | Source viewer | Review the schematic and layout, not just the copper. |
| Debugging a board on the bench | Source viewer | You need nets, part values and the schematic. |
| Reusing or forking an open-hardware project | Source viewer | You'll continue from the project, not the Gerbers. |
| Sharing a design with someone without KiCad | Source viewer in the browser | They see schematic, PCB and 3D with no install. |
Which tool for which
- Only Gerbers: Ucamco's Reference Gerber Viewer is the strongest pure Gerber viewer, and tracespace view keeps files in your browser. See the ranking.
- The KiCad project: BoardRepo is a browser viewer for KiCad-centered projects. It shows the schematic, PCB, 3D view and BOM, keeps saved versions you can compare, and lets you share the board publicly, by link or with a password, and keep editing in desktop KiCad. It isn't a fabrication service and some uploads don't render fully, so check its view against your files.
- Both, for one board: check the Gerbers in a Gerber viewer before you order, and keep the project somewhere you and your reviewers can open it.