How to compare two PCB revisions

Use source history and visual review together

Git diffs are useful for KiCad source provenance and review, and CI can produce checks and previews. A schematic or layout also has spatial relationships that are easier to inspect as a drawing. Altium's binary source needs suitable native or derived comparison tools. Use a visual difference to focus inspection while keeping the source version and its check results available.

Compare on BoardRepo

Open the board, open Version history, and choose Compare versions. Pick the From and To published versions; they need compatible, available comparison data and need not be neighbours. Comparing requires sign-in and board access. Public viewing does not require sign-in; other sharing modes require their own access proof.

The result is the board you already know, drawn twice and dimmed, with the changes painted on top so the render is context and the highlight is signal. The same is done for the schematic. Beside the drawings is a list of every change by name, grouped as Parts (a component added, removed, moved, rotated, flipped, renamed, or given a new value or footprint), Routing (tracks, vias, and zones and their fills), Board (outline size and layer stackup) and Other. Selecting a change in the list highlights it on the board, and clicking a highlight selects its row.

What it needs from the two versions

Both sides need the required rendered data. Publishing source does not guarantee it; a version that failed to render says so in its pane rather than showing an empty frame that reads as “nothing changed”. Both sides must be the same kind of design: a KiCad version and an Altium version of the same board cannot be compared to each other, and two Altium versions compare once both have been converted by the same converter generation. When a pair cannot be compared, the page says which of these is the reason instead of guessing.

The comparison is built from the renders BoardRepo already has for each version, so it is included in personal core features. It is not a design-rule check and has no electrical pass verdict. Inspect the differences and run the relevant checks.

Reviewing a change made with AI

Save the baseline before the edit, then save the changed files as another version of the same board. Open that exact pair in Compare versions and check the differences against what you asked for. An assistant's explanation describes its intent; the comparison shows what reached the saved design. Look for unrelated component, routing and outline changes as well as the intended edit.

Confirm both sides rendered before treating an empty change list as evidence. Then open the changed source in KiCad and run the checks relevant to the edit. For the connection, saving permissions and limits of the assistant's reading context, see KiCad with Claude or ChatGPT. Restoring an earlier version here does not automatically change files in a local KiCad workspace. Download the version you intend to continue, or use Pull when it is the current remote version offered by the plugin.

Using it in a review

The habit that makes this useful is to version at review boundaries: publish the revision you want reviewed, send the board link, and ask the reviewer to compare it against the last version they approved. Read the change list, inspect highlighted areas and their context, and check for unintended changes. Small visual differences can have large electrical consequences; the amount of highlighting does not determine the review time.

If the review turns up a mistake, restore the earlier version as the latest from the same Version history dialog. The restore is a new version, so the mistaken revision stays in the history and can itself be compared against later.

Find a board with several versions to try it, or read about version control for PCB designs.

Continue your work

Connect your AI to inspect board context and use separately approved personal saving where available. Use BoardRepo for KiCad to Push and Pull versions from the editor. For a shared organization workspace, contact us about Team.