What is a Gerber file?

Gerber is a file format used in PCB design and manufacturing. It was originally developed by Gerber Systems Corp., a division of Ucamco. The Gerber format precisely describes the 2D images (copper layers, solder mask, drill data, etc.) that make up a PCB.

Gerber files typically have the file extension .gbr or .pcb and are output from PCB design software like Altium Designer, Eagle, KiCad, etc. The PCB manufacturer then uses these Gerber files to fabricate the physical circuit board.

Here are the main types of Gerber files:

File Extension	Layer
.GTL	Top copper layer
.GBL	Bottom copper layer
.GTO	Top silkscreen overlay
.GBO	Bottom silkscreen overlay
.GTS	Top solder mask
.GBS	Bottom solder mask
.GKO	Board outline
.GPT	Top pad master
.GPB	Bottom pad master
.TXT	Drill/NC drill file

The Gerber format has evolved over the years. The current standard is the Extended Gerber or X2 format. This human-readable format provides extra metadata and makes viewing and validating Gerber files easier.

How to view Gerber files online for free

Now that we’ve covered what Gerber files are, let’s look at some of the best free online Gerber viewers available:

1. Gerber Viewer by Ucamco

Gerber Viewer is a free online Gerber file viewer developed by Ucamco, the company behind the Gerber format. It supports the latest X2 format and provides a full-featured interface for viewing PCB layer data.

To use it:
1. Go to https://gerber-viewer.ucamco.com
2. Drag and drop your Gerber files into the browser window, or click “Open Files” to select them
3. The PCB will be rendered in the viewer. You can toggle individual layers on/off, measure distances, view layer properties, and export images.

Gerber Viewer provides an excellent, standardized way to view Gerber files online. The only downside is you have to upload your files to Ucamco’s servers.

2. CircuitPeople Gerber Viewer

CircuitPeople is an electronics manufacturing marketplace that offers a free, browser-based Gerber viewer. Their viewer supports X2 as well as older X1 Gerber formats.

To use it:
1. Go to https://circuitpeople.com/gerber-viewer/
2. Click “Upload Gerber zip file” and select your Gerber files (which must be zipped into a single archive)
3. The PCB will be rendered. You can toggle layers, pan/zoom, measure, and even get an automated manufacturability check.

CircuitPeople’s viewer interface is clean and easy to use. However, you can only upload Gerber files as a single zip archive, not as individual files.

3. EasyEDA Gerber Viewer

EasyEDA is a cloud-based PCB design tool that also offers a free online Gerber viewer. It’s a convenient option if you already use EasyEDA for PCB design.

To use it:
1. Go to https://easyeda.com/editor/GerberViewer
2. Click “Open” and select your individual Gerber files
3. The viewer will render your PCB. You can toggle layers, pan/zoom, measure, and even do a 3D view.

EasyEDA’s viewer works well and has a great 3D view option. But it requires Adobe Flash to be enabled in your browser, which can be a security risk and is not supported by all browsers.

Other free Gerber viewers

In addition to the fully online Gerber viewers described above, there are also some great installable options that are still free:

• Gerbv – Open source, multiplatform Gerber viewer for Linux, MacOS and Windows.
• KiCad GerbView – Gerber viewer included with the free, open source KiCad PCB design suite.
• ViewMate – Free Gerber viewer for Windows. Old but still works.

These programs require downloading and installing, but provide additional features and offline access compared to the web-based viewers.

Why use an online Gerber viewer?

So with these installable options available, why bother with an online Gerber viewer? There are a few key benefits:

1. Convenience – Online viewers let you quickly view Gerber files without needing to download or install anything. Just open a web browser and drag-and-drop.

2. Collaboration – With a web-based viewer, you can easily share a link to your Gerber files with colleagues or your manufacturer, without having to send the actual files.

3. Cross-platform – Online Gerber viewers work on any operating system and computer. You get the same interface whether you’re on Windows, Mac, or Linux.

4. Always up-to-date – With web apps, you always get the latest version without having to manually update. Developers can roll out fixes and new features instantly.

5. Free – Perhaps most importantly, the online Gerber viewers listed here are totally free to use. No license costs, subscriptions, or trial periods.

Of course, there are tradeoffs. Online viewers require an internet connection, may be slower than native apps, have fewer advanced features, and involve uploading your design files to a third party. But for quick, no-hassle Gerber viewing, the convenience of online viewers is hard to beat.

FAQ about viewing Gerber files

To wrap up, here are answers to some common questions about working with Gerber files:

What’s the difference between Gerber X1 and X2 formats?

Gerber X1 (274X) is an older format that combines image data and aperture definitions into a single file. X2 is the newer, preferred format that uses separate files for copper layers, silkscreen, soldermask, etc. and includes additional metadata. The online viewers described here support both X1 and X2.

Can I edit Gerber files with these viewers?

No, the free online Gerber viewers are read-only. They let you view and inspect PCB data, but not make changes. To edit Gerbers, you would need to go back to your original PCB design software.

My manufacturer asked for “Gerber files” – what should I send them?

Typically this means sending a zip archive containing all the individual Gerber (.gbr/.pcb) and drill (.txt) files that make up your PCB – one for each copper layer, soldermask, etc. Your PCB design software should have a “fabrication output” option that will automatically generate a set of Gerbers to send to your manufacturer.

The Gerber viewer isn’t displaying my PCB correctly – what could be wrong?

This is likely due to an issue with your Gerber files themselves. Common problems include missing files (e.g. forgetting to include the .txt drill file), incorrect file extensions, or invalid formatting. Double check that your design software is set up to generate compliant Gerber files. You can also try uploading to a different online viewer to cross-reference.

Can I view other electronics design files with these tools?

The viewers covered here only support Gerber format PCB files. They cannot be used to view other electronics/CAD file formats like EAGLE .brd, Altium .PcbDoc, KiCAD .kicad_pcb, or generic CAD formats like .dxf and .dwg. For those, you would need to use the original design software or find a specialized viewer.

Conclusion

Whether you’re a PCB designer sending files to manufacturing or just curious to see what a circuit board design looks like, knowing how to view Gerber files is an essential skill. And with the excellent free, web-based Gerber viewers now available, you can do so quickly and easily from any computer.

Just remember – while incredibly useful for inspection, online viewers are not a replacement for desktop PCB design software. Always generate your fabrication files from a dedicated PCB design package using the manufacturer’s recommended settings.

Armed with this knowledge, you’re ready to take advantage of the power and convenience of online Gerber viewing. The next time you need to check a PCB design, give one of these free browser-based viewers a try!