What CADPreview Actually Shows You (Without Opening KiCad)
By the CADPreview Team · Series: Hardware Visibility
"The most useful tool isn't the one with the most features. It's the one the whole team will actually open."
Design visibility only works if it doesn't require the design tool.
The previous two articles in this series were about problems: firmware engineers working from stale schematics, supply chain quoting against BOMs that no longer match the board being built. The cause in both cases was the same: design information locked inside a desktop application that most of the team cannot open.
This article is about the solution. Specifically, what CADPreview shows you and how it works.
First: How It Actually Works (And Why That Matters)
CADPreview connects to your KiCad project through GitHub. When you open a design, the files are streamed directly from GitHub to your browser. They are not uploaded to CADPreview's servers. They are not stored anywhere other than where they already live, in your repository.
This is worth being explicit about because it is the reason a CTO or an IP-conscious team should not hesitate to use it. Your proprietary design files do not pass through or rest on infrastructure you didn't choose. CADPreview reads your repository structure and authenticates the connection. The files go straight to the browser that renders them.
What You Can See
Schematics and PCB Layout
The obvious one. Open a KiCad schematic or PCB layout in a browser, on any machine, without installing KiCad. The rendering is not a static image. You can pan, zoom, and inspect individual components. For multi-sheet designs, each sheet is accessible via the side panel.
For a firmware engineer checking a pinout, a programme manager reviewing progress, or a CM verifying a component placement before asking a question, this removes the single biggest barrier: the need to either have KiCad installed or wait for someone to export something.
This is not a PDF viewer. A PDF is a snapshot that begins diverging from the source the moment it is generated. What you are looking at in CADPreview is the actual design file, at the revision you selected, rendered live.
Revision Access and Branch Browsing
This is where the GitHub integration pays off.
Every commit in your repository is a point-in-time snapshot of the design. CADPreview makes all of them navigable. You can open any tagged release, Rev A, Rev B, the prototype build, alongside the current state of main, and switch between them without downloading or installing anything.
You can also browse branches. If a hardware engineer is working on a power supply redesign on a feature branch, the firmware engineer can open that branch in CADPreview and check whether the GPIO assignments they are writing to are still valid. Not from a forwarded export. From the branch itself, before it is merged.
Spotting that a component changed between Rev A and Rev B, or verifying that a last-minute ECO made it into the release commit, becomes a question of opening two tabs and navigating to the relevant part of the design.
BOM View with Datasheet Links
The bill of materials is generated live from the PCB, at whatever revision you have open. Not from a spreadsheet someone exported last Thursday. From the source.
For this to be genuinely useful, engineers need to do their part: populate the manufacturer part number and datasheet URL fields in the schematic component properties. When they do, every line in the BOM becomes a direct link to the component datasheet. Supply chain can pull the datasheet for any part without asking, without searching Octopart, without emailing the hardware engineer. The relevant document is one click away, tied to the exact part specified in the design.
Annotations
There are two tools here, built for different situations.
The first is a drawing surface directly over the schematic or PCB. You can draw freehand, erase, and add text on top of the live design. It was built with video calls in mind: if you are walking someone through a design over a call, you annotate directly on the document rather than waving a cursor at something and hoping they are following. On a tablet with a pen it feels particularly natural, the kind of interaction that makes a project review actually productive rather than someone sharing a screen and talking at a PDF. When you are done, save it as a PNG and attach it wherever it needs to go: a Jira ticket, an email, or a Slack message.
The second is a Markdown editor for more formal notes: a decision that needs recording, a component change that needs justifying, a review comment that needs to survive longer than a conversation. A dedicated capture tool lets you select a section of the schematic or PCB and insert it directly into the Markdown, so the note always shows exactly what it refers to. The finished document exports as a PDF.
Project Links for Controlled Sharing
Sharing a design is a one-time setup. Connect the GitHub repository, generate a Project Link, and send the URL. Anyone with that link can view the design in a browser without a CADPreview account and without installing anything.
Links can be named, which is useful when you are sharing the same design with multiple parties and want to track which link is active, and can be disabled at any time from the project settings. If you share a design with a CM for a specific build and want to revoke access after handoff, disabling the link takes seconds and needs no action from the recipient.
Private repositories require a Pro account to connect. Public repositories are free.
Who It Is For
The people who benefit most from CADPreview are the people who have always been outside the loop: firmware engineers who need to check a pinout without interrupting the hardware engineer, supply chain teams who need a live BOM rather than last week's export, programme managers who want to see where the design is without scheduling a review meeting, CTOs who want visibility into the project without learning a new tool.
Hardware engineers use it too, and not just as a side effect of everyone else being in the loop. When you want to check what DCDC IC you used on a previous design, or what load capacitor value you settled on for that crystal, you do not need to find the project folder, launch KiCad, and wait for it to load. You open a browser, navigate to the project, and you are looking at the answer in seconds. CADPreview becomes a frictionless window into your own back catalogue: every past design, every decision you made and might want to repeat, immediately accessible.
CADPreview is a web-based viewer for KiCad projects hosted on GitHub. Connect your repository once, share a link, and your whole team sees the current schematic, layout, and BOM in a browser, on any branch, at any release, without installing anything.