Is your sitemap file clean for the year-end audit?

What gets checked

• The file. Well-formed XML, the sitemap namespace, a byte order mark at the start, UTF-8, and the plain thresholds: 50,000 URLs and 50 MB (52,428,800 bytes) per file, 2,048 characters per address.
• The addresses. Relative or malformed locations, mixed hosts, http and https side by side, trailing slashes used both ways, duplicates, entries that differ only by letter case, #fragments and query strings.
• The dates. Entries with no lastmod, dates in an invalid format, dates in the future, with time zones read correctly.
• The index. For a sitemap index, the list of child sitemaps with their dates.

How the corrected list is made

Every address gets your preferred scheme and a lower-case host. The www and non-www forms of your host are joined, while addresses on other hosts are left out. Fragments are removed, one slash style is used for page addresses, relative locations are resolved against your host, and repeats are dropped. Query strings stay, so you decide about them.

The CSV has one row for every entry: where it was, what happened to it and why. Open it in any spreadsheet.

Keep going

The full routine, with a worked example of twelve URLs, is in sitemap hygiene before year-end. While the year-end audit is open, score the pages themselves with the 12-point self-check, and build the plain-text summary file with the llms.txt generator.