Gerber Viewer
Free online Gerber viewer. Open RS-274X Gerber and Excellon drill files in your browser, stack PCB layers with auto colors, zoom, pan and fit-to-window. No upload, 100% local.
How are negative (clear) polarity layers handled?
Shapes drawn with clear polarity, for example via %LPC*% or an LP C command, are approximated by painting them in the canvas background color, so cut-outs look right in the stacked view. This is simplified compositing: unlike a photoplot-grade renderer it does not compute true per-layer knockouts, so where clear shapes overlap other layers the edges can differ slightly. Treat the result as a design review aid, not a final film proof.
What is a Gerber file?
Gerber is the standard image format the PCB industry uses to describe each copper, soldermask and silkscreen layer of a circuit board. Your CAD tool exports one file per layer, and the fabrication house reads these files to etch and print your board. This viewer opens the modern RS-274X format used by virtually every current EDA package.
Which file types can I open?
Any RS-274X Gerber file regardless of extension — .gbr, .gtl, .gbl, .gts, .gbs, .gto, .gbo, .gko, .gml, .art, .pho and more — plus Excellon drill files (.drl, .drl, .xln, .exc). The parser detects gerber versus drill automatically, so .txt exports from KiCad or Altium work too.
Are my board designs uploaded anywhere?
No. Parsing and rendering happen entirely inside your browser with JavaScript. The files never leave your device, which makes the tool safe for confidential pre-production layouts.
How are multiple layers displayed?
Every loaded file is plotted into the same millimeter coordinate system and stacked in upload order, each in its own auto-assigned color, so copper, mask, silk and drill overlays line up exactly as on the finished board.
Can I hide or remove individual layers?
Yes. Each row in the layer list has an eye toggle to show or hide that layer, a delete button to remove it from the stack, and a re-parse button that re-runs the parser on the same file — handy when you fixed a typo in the export and reload.
Why does one broken file not break the whole view?
Each file is parsed in isolation. If a file is malformed or simply not a Gerber, that layer is flagged with an error and everything else keeps rendering, so one bad export never costs you the whole inspection.
How do I zoom and pan the board?
Scroll the mouse wheel to zoom in and out around the cursor, drag with the mouse or finger to pan, and press the fit-to-window button to frame the whole board again. On touch screens you can pinch with two fingers.
What do the colors mean?
Colors are assigned automatically per file based on its extension — for example red for top copper (.gtl), blue for bottom copper (.gbl) and gold for drill hits — so you can recognize layer roles at a glance. They are a viewing aid only and do not change the data.
How large a board can it handle?
Files up to about 10 MB are processed comfortably in the main thread, which covers virtually all real two- and four-layer boards. Extremely large or exotic macro-heavy files are capped for rendering and the viewer tells you so.
Does it support old RS-274D files?
RS-274D files lack embedded aperture lists and need a separate wheel file, so they are not reliably supported. Nearly every modern CAD tool exports RS-274X with embedded apertures — make sure that option is selected when generating your outputs.
Can I check my design before sending it to a fab house?
Yes — that is exactly what it is for. Stack your fab outputs, check that pads align with drills, silkscreen clears the soldermask and the board outline is closed, and catch problems before they become manufacturing defects.
Does the viewer work offline?
After the page and its bundled parser have loaded, everything runs locally, so an interrupted connection does not stop you from inspecting files you have already opened.
How to Use Gerber Viewer
This viewer renders PCB fabrication outputs — RS-274X Gerber layers and Excellon drill files — as one stacked board view, entirely inside your browser. Layers are plotted into a shared millimeter coordinate system with automatic colors, so copper, mask, silk and drills line up exactly as the finished panel will. Files never leave your device.
- Drop your Gerber or drill files onto the upload zone (or click it to browse). Multiple files at once are fine — each becomes its own layer.
- Prefer to explore first? Press "Load sample board" to see a demo stack of top copper, bottom copper and drill layers.
- In the layer list, click the eye icon to hide or show a layer, the trash icon to remove it, or the circular-arrow icon to re-parse that file after fixing an export.
- Zoom with the mouse wheel (or pinch on touch screens) and drag anywhere on the board to pan; "Zoom in" and "Zoom out" buttons work too.
- Press "Fit to window" at any time to frame the whole board again.
- Check the layer rows for per-file object counts and board size; a row turns red with an error note if one file could not be parsed, without affecting the rest.
Before sending outputs to a fab house, stack the top copper and drill layers and zoom into a few pads — misaligned drills and closed vias are the two most common last-minute catches.
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