Free Online Gerber Viewer (No Signup)
Also opens DWG, DXF, STEP, IGES, IFC, SKP, STL, OBJ, GLB, FBX, 3DM and other 3D/CAD files — drop any file on the viewer.
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What Is a Gerber File?
A Gerber file is a photoplotter program. It says which shape to use (an aperture), then where to move it, drag it, or flash it down. Drag a round aperture along a path and you have a trace; flash a rectangle and you have a pad; fill a contour and you have a ground pour. Because each file describes exactly one layer of the board, a design is exchanged as a fabrication package: a folder or zip holding one Gerber per copper, mask, silkscreen and paste layer, one for the board outline, and an Excellon drill program listing every hole and its diameter.
The format everything writes today is RS-274X (extended Gerber), where the aperture definitions live inside the file. Its current revision, sometimes called Gerber X2, adds attributes that state what each file is for, like %TF.FileFunction,Copper,L1,Top*%, which is what lets a viewer name and order the layers of a board it has never seen. The older RS-274D kept its apertures in a separate wheel file and cannot be rendered on its own by anything.
Gerber is a 2D format with no notion of the board as a solid, which is the opposite of a STEP model of the same assembly. What it does carry is manufacturing truth: the copper that will actually be etched, to the micrometre, which is why it is what a board house asks for.
Who Uses Gerber Files?
Electronics engineers and PCB designers, who export a fab package from KiCad, Altium Designer, Eagle, OrCAD/Allegro, PADS, Fusion 360 Electronics or EasyEDA at the end of every board revision; the board houses and assembly shops that receive it; procurement and quality staff checking that the package they are about to send out is complete and is the right revision; and anyone who has been emailed a zip of Gerbers and needs to look at the board without installing an EDA tool.
Common Use Cases
- Check a fabrication package before sending it to a board house
- See what a zip of Gerbers someone emailed you actually contains
- Confirm the drill file matches the pads on the copper layers
- Compare two revisions of a board layer by layer
- Read the board dimensions and hole sizes off the files themselves
- Look at a client’s board on a phone or a machine with no EDA software
Features
The Whole Board, Not One Layer
Drop the fabrication package as a .zip and every Gerber and drill file in it is read and stacked in fabrication order, so you see the board.
Layers Named Automatically
Copper, solder mask, silkscreen, paste, outline and drill are identified from Gerber X2 attributes, or from the filename when a package has none.
Any Naming Scheme
Every file is recognised by reading it, so .GTL, .art, .001 or no extension at all all open, and the drill file is found even when it is called .txt.
Clear Polarity Handled
Clearances in a ground pour erase only their own layer, composited separately, so an inner plane never punches a hole through the copper below it.
Aperture Macros
Rounded rectangles, thermals, moiré targets, outlines and vector lines, with the parameter arithmetic macros use, all render as the pad shapes they define.
Drill Holes and Slots
Excellon plunges render at their true diameter and routed slots as slots, with the hole count and every drill size reported.
Board Size at a Glance
The model info panel reports the board dimensions read off the outline layer, the copper layer count, hole count and drill sizes.
Arcs Drawn as Arcs
Single- and multi-quadrant arcs, full circles and swept apertures come out smooth, chorded to a quarter of the finest feature any fab images.
Older Files Too
Trailing-zero suppression, inch units, image polarity, mirror and offset: the deprecated commands real CAM output still contains are all read.
Layer Toggles
Every layer has its own switch. Mask and paste start hidden because their features are openings in a film, and would cover the copper you are checking.
Nothing Is Uploaded
The package is read and drawn entirely in your browser. No account, no upload, no copy of your board on a server.
Share and Embed
Send a link that opens the board in any browser, or drop the viewer into your own page with one iframe.
Compatibility & Format Notes
Extended Gerber (RS-274X and Gerber X2) is read in full: all four standard aperture templates with optional holes, aperture macros (including outlines, thermals, moiré targets and the rounded rectangles KiCad generates), regions, single- and multi-quadrant arcs, clear polarity, block apertures, step & repeat, aperture mirror/rotate/scale, and the deprecated image polarity, mirror, offset and scale commands that older CAM output still uses. Excellon drill and route files are read alongside, with both zero-suppression conventions, inch and metric units, and G85 slots. Layers are identified from their X2 file-function attributes where present and from their filenames otherwise, covering the naming schemes of every common tool, and files are recognised by their contents rather than their extensions, so a package whose layers are named .art, .001, or nothing at all still opens. Legacy RS-274D files are recognised and explained: their aperture list is in a separate file, so no viewer can render them.
Embed on Your Website
Add this viewer to your own site with a single line of HTML. Click Embed in the toolbar to generate an embed code, or use the snippet below with your own file URL.
Your Files Stay on Your Computer
Your Gerber files are parsed entirely in your browser. Nothing is uploaded, stored, or shared unless you explicitly click the Share button. Shared files are hosted for 90 days then deleted.
Frequently Asked Questions
▶How do I view a whole board rather than one layer?
Zip the fabrication folder and drop the .zip on the viewer. Every Gerber and drill file inside is read and stacked in fabrication order, so you see the board rather than a single layer, with each layer on its own toggle in the layer panel. A single .gbr opens on its own too, it is just one layer of the board.
▶Why is the solder mask hidden when the board opens?
Because a solder mask Gerber draws the openings in the mask, not the mask itself. Painting those over the copper would cover exactly the pads you are usually checking, so mask and paste layers start hidden and copper, silkscreen, outline and drill start visible. Turn any of them on in the layer panel; the mask draws as a translucent green film so you can see the copper through it.
▶My layers are named .GTL, .GBL, .GTS — will they open?
Yes. Every file is identified by reading it, not by its extension, so the Altium, Eagle, OrCAD and KiCad naming schemes all work, as do packages whose layers have no extension at all. Where a file carries a Gerber X2 file-function attribute, that names the layer exactly. Where it does not, the filename is matched against the schemes the common tools use.
▶What about the drill file?
Excellon drill and route files are read as part of the package, and open on their own as well. Holes render at their true diameter on their own layer, routed slots as slots, and the model info reports the hole count and every distinct drill size. A drill file named .txt is found by its contents, which is how most tools name it.
▶Why won’t my .gbrjob file open?
A .gbrjob is the JSON index of a fabrication package: it names the layers and the stackup but holds none of their geometry. Zip the folder it came in and upload that instead.
▶What is RS-274D and why can’t it be displayed?
RS-274D is Gerber before 1998. It lists coordinates and D-codes but no aperture definitions: the shapes it draws with lived in a separate aperture wheel file that is not part of the upload, so nothing can render it. Re-export from your PCB tool as extended Gerber (RS-274X), which every current tool writes by default.
▶Is this Gerber viewer really free?
Yes, completely free. No signup, no watermarks, no file size limits on the viewer (the optional share-link feature has a 100 MB upload cap). Built by Innerscene as a tool for architects, engineers, and designers.
▶Are my files uploaded to a server?
No. All parsing, rendering, and conversion runs in your browser — nothing is uploaded, stored, or transmitted by default. The Share button is the only feature that uploads a file, and only when you explicitly click it.
▶Can I convert to another format?
Yes. Click Export in the toolbar to save as STL (3D printing), OBJ (Wavefront), GLB (glTF binary), or PDF (snapshot of the current view).
▶Can I embed this viewer on my own site?
Yes. Click Embed in the toolbar to generate a one-line <iframe> snippet you can paste into any HTML page. You can choose whether the embed shows the viewer’s toolbar.
The sample board is the Arduino Uno Rev3 reference design, © Arduino, licensed CC BY-SA and redistributed unmodified. Arduino is a registered trademark of Arduino S.r.l.; Innerscene is not affiliated with Arduino. Gerber is a registered trademark of Ucamco.