Maker Tools
Online Gerber Viewer
Drop your RS-274X Gerber layers, an Excellon drill file, or a full fab zip and preview the board right here. Zoom, pan, toggle layers, and read off the board size before you send it to be manufactured. Everything runs in your browser, so nothing is uploaded.
Drop Gerber, drill or a fab .zip here
Individual layers (.gtl .gbl .gts .gbs .gto .gbo .gm1 .drl) or a full zipped board package.
What is a Gerber file?
A Gerber file is the standard way to describe one layer of a printed circuit board. The modern format, RS-274X (also called Extended Gerber or X2), is a plain-text vector format: it defines a set of apertures (the shapes of pads and the width of traces) and then a sequence of draw, move and flash operations that place copper, soldermask, silkscreen or the board outline. Every fab house on earth, JLCPCB, PCBWay, OSH Park and the rest, accepts Gerber as the canonical manufacturing input. This online Gerber viewer reads that format directly in your browser so you can sanity-check a board before you pay for it.
Gerber and drill file extensions
A board is exported as one Gerber file per layer plus one Excellon drill file for the holes. The common extensions are: .gtl and .gbl for top and bottom copper, .gts / .gbs for top and bottom soldermask, .gto / .gbo for silkscreen, and .gm1 or .gko for the board outline (edge cuts). Some tools use a generic .gbr extension and rely on an embedded file-function attribute instead. This viewer reads the extension when it can and falls back to sniffing the file contents when it cannot.
What is an Excellon drill file?
Holes are not part of the copper Gerbers. They live in a separate Excellon file (often .drl, .xln or a .txt). An Excellon file lists a table of tools, each with a drill diameter, then a series of X/Y coordinates where each tool strikes. This viewer parses metric and imperial Excellon, both leading and trailing zero suppression, and draws every hole as a light circle over the copper so you can confirm pad-to-hole alignment.
Is my board uploaded anywhere?
No. This Gerber viewer is completely client-side. When you drop a file or a zip, it is read with the browser FileReader API and, for zips, unpacked in the browser itself (stored entries by byte slicing, compressed entries with the built-in DecompressionStream). No file is ever sent to a server, so it is safe to inspect confidential or unreleased designs. Close the tab and nothing is retained.
Frequently asked questions
What files do I need to view my PCB?
Export your board as RS-274X Gerbers (one file per layer) plus an Excellon drill file, then drop them here. You can add layers one at a time or drop a whole fab zip and the viewer sorts each file into the right layer.
Can I open a Gerber zip from KiCad, JLCPCB, or PCBWay?
Yes. Drop the zipped fab package straight in and it is unpacked in your browser. The viewer reads standard extensions like .gtl, .gbl, .gts, .gbs, .gto, .gbo, .gm1 and .drl, and falls back to reading the file contents when the extension is generic such as .gbr.
Are my Gerber files uploaded to a server?
No. Everything runs on your device. Files are read with the browser FileReader API and zips are unpacked locally, so nothing is sent anywhere. It is safe to inspect confidential or unreleased designs, and closing the tab leaves no copy behind.
What is the difference between a Gerber file and an Excellon drill file?
Gerber files describe the flat layers: copper, soldermask, silkscreen and the board outline. Holes are not in the Gerbers; they live in a separate Excellon file that lists each drill tool diameter and the coordinates where it strikes. This viewer draws the holes as circles over the copper so you can check pad alignment.
How do I check my board size before ordering?
Load your outline layer (edge cuts) along with the copper and the viewer reads the board width and height straight off the geometry, shown in millimetres in the top-left corner of the canvas. Confirm that number matches your intended board dimensions before you pay for fabrication.
A layer is missing or the board looks wrong. What happened?
The viewer only renders layers it can recognise, so a missing layer usually means that file was not included or used an unfamiliar extension. Check the layer list to see what loaded, look at the parser warnings panel for any lines it could not read, and try dropping the file again as part of the full fab zip.
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