How are requests matched between the two files?

Requests are paired by their HTTP method plus full URL. When the same method+URL appears more than once, the occurrences are matched in order. Anything only in A is “removed”, anything only in B is “added”, and matched pairs are “changed” or “unchanged” based on status, size, and time.

What do the colors mean?

Deltas are shown from A to B. Red means a regression in B (larger transfer or slower), green means an improvement (smaller or faster). This applies to both the per-request delta columns and the summary totals.

Are my HAR files uploaded?

No. Both captures are read and compared locally in your browser. Nothing is sent to a server — which matters because HAR files often contain auth headers, cookies, and request bodies.

Compare Two HAR Files (Diff)

Load two HAR captures and diff them request by request. The tool pairs requests by method and URL, then shows what was added, removed, or changed — with status, transfer-size, and timing deltas color-coded so regressions (bigger or slower in the second capture) stand out from improvements. Ideal for before/after performance work, comparing two environments, or A/B captures. Both files are parsed entirely in your browser and never uploaded.

How to use HAR Compare / Diff

Export two HAR files from your browser DevTools (Network tab → “Save all as HAR”) — for example one before and one after a change.
Drop the baseline into A and the comparison into B (or paste the JSON).
Read the summary cards for the overall change in request count, transfer size, and load span.
Filter by Added / Removed / Changed and search by URL to focus on what moved.
Use Swap A/B to flip the direction of the comparison.

Frequently asked questions

How are requests matched between the two files?: Requests are paired by their HTTP method plus full URL. When the same method+URL appears more than once, the occurrences are matched in order. Anything only in A is “removed”, anything only in B is “added”, and matched pairs are “changed” or “unchanged” based on status, size, and time.
What do the colors mean?: Deltas are shown from A to B. Red means a regression in B (larger transfer or slower), green means an improvement (smaller or faster). This applies to both the per-request delta columns and the summary totals.
Are my HAR files uploaded?: No. Both captures are read and compared locally in your browser. Nothing is sent to a server — which matters because HAR files often contain auth headers, cookies, and request bodies.

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