When to use this tool
Submitting your whole sitemap on every deploy is the fastest way to hit a 429. A diff turns a full sitemap into just the URLs that actually changed.
After a content deploy
Compare the sitemap before and after a release to get exactly the pages that release touched.
On a large site
When a sitemap holds thousands of entries, the changed set is usually a handful. Submit that instead.
When lastmod is reliable
If your generator writes accurate lastmod values, changed pages can be detected without crawling anything.
Auditing a release
The diff doubles as a record of which URLs a deploy added or modified.
How to diff two sitemaps
Both files are parsed with the browser's own XML parser. Neither file is uploaded.
- 1
Save a baseline sitemap
Download your sitemap XML before a release, or keep the copy from your last submission.
- 2
Upload both files
Add the older file as the baseline and the newer one as the current sitemap.
- 3
Choose what to include
Added URLs are new entries; changed URLs are entries whose lastmod moved. Include either or both.
- 4
Copy, download, or submit
Export the queue as text, or send it straight to the submission form for the matching host.
What usually goes wrong
Uploading a sitemap index
An index only lists other sitemaps. Upload the individual sitemap files it points to — this tool stays browser-only and does not fetch them.
Generators that restamp every lastmod
Some tools rewrite every lastmod on each build, which makes every URL look changed. Check before submitting the whole set.
Missing lastmod values
Without lastmod, only added URLs can be detected — an edit to an existing page is invisible to a diff.
Mixed hosts in one sitemap
A sitemap spanning several hosts produces a queue you still have to split before submitting.
Frequently asked questions
- Why upload files instead of entering a sitemap URL?
- Reading another site's sitemap from the browser is blocked by CORS, and fetching it server-side would mean sending us your URLs. Uploading keeps the comparison local.
- How is a changed URL detected?
- A URL present in both files whose lastmod value differs counts as changed. URLs found only in the newer file count as added.
- Are removed URLs reported?
- They are counted but not exported. IndexNow notifies about updates, and a deleted URL is better handled by letting the engine recrawl it.
- Can I compare gzipped sitemaps?
- No. Decompress the .xml.gz file first — only plain XML is parsed.
- Does the queue respect the 10,000 URL limit?
- A diff can produce more than that. Run a large result through the batch builder if you are near the limit.