Parse without inventing precision
Each raw lastmod, calendar date, instant, timezone, precision, source file, and snapshot date is preserved. Date-only values remain date-only.
Local technical SEO QA
Sitemap Lastmod Integrity Auditor
Compare one sitemap snapshot or a dated history to see whether <lastmod> values are valid, precise, stable, reversed, future-dated, broadly reset, or disconnected from supplied content-hash evidence.
Browser-only processingNo accountUp to 1M recordsCSV, JSON, Markdown exports
Step 1
Add sitemap snapshots
Use XML URL sets, sitemap indexes, or CSV files with URL, lastmod, and optional sitemap name columns. ZIP and GZIP archives are supported. Snapshot dates are inferred from filenames when possible.
Processed locally in your browser. Your files are not uploaded. A normal refresh clears the input.
Sitemap files
Drop XML, CSV, ZIP, GZ, or GZIP files here, or choose files.
Optional content-hash evidence
CSV columns: URL, hash, crawl date, and optional status, canonical, and template.
Step 2
Review discovered files and dates
No files added yet. Load the sample or choose sitemap files above.
| File | Role | Size | Snapshot date | Action |
|---|
For an archive, the selected date is a fallback. A valid date inside each child filename takes precedence. Sitemap indexes are resolved against uploaded filenames only.
Step 3
Configure evidence rules
Step 4
Run the local audit
Parsing, comparison, and aggregation run in a Web Worker so the page remains responsive. Cancel any long job without losing the selected files.
Add files or load the sample to begin.
Step 5
Review evidence and export
Transparent score
Signal integrity factors
The summary score is the equal-weight average of these named factors. Counts and reasoning remain visible; no finding is hidden behind the score.
Evidence-backed findings
| Severity | Finding | Evidence | Next action | URL or group | Snapshot |
|---|
Snapshot timeline and change distribution
| Snapshot | Records | URLs | Added | Removed | Re-added | Advanced | Unchanged | Reversed |
|---|
Timestamp and URL-group clusters
No clusters met the configured thresholds.
| Issue type | Timestamp | Snapshot | Count | Share | Paths | Templates |
|---|
URL history drill-down
| URL | Template | Events | Change sequence |
|---|
Sitemap file, index, and parse diagnostics
How the integrity analysis works
Compare histories and groups
The analyzer tracks additions, removals, re-additions, advances, reversals, stale evidence, uniform resets, precision shifts, timezone shifts, and peer cadence.
Use hashes as supplied evidence
Hash and lastmod transitions are compared in four explicit combinations. Equal hashes are never treated as proof that a page did not meaningfully change.
Accepted formats, limits, and deliberately unsupported behavior
Accepted: XML sitemap URL sets and indexes, sitemap CSV, ZIP/GZIP archives, and content-hash CSV.
Not fetched: child sitemap URLs, live pages, Search Console, Merchant Center, analytics, or third-party APIs.
Limits: 1,000,000 URL-snapshot records; 200 MiB per compressed file; 300 MiB combined input; 500 MiB expanded archive data; 500 archive entries. Split larger histories into separate audits.
Unsupported: encrypted archives, non-UTF-8 text, user-defined regular expressions, and treating image/video/news extensions as HTML pages.
Sitemap lastmod audit FAQ
Does the auditor upload my sitemap or crawl files?
No. Files are parsed and compared in your browser. The application does not send file contents, URLs, hashes, titles, or issue examples to the server or analytics.
Does a lastmod warning mean I should update the timestamp?
No. Stable pages can legitimately retain the same lastmod. Update timestamps only when meaningful page content changes; do not manufacture freshness.
What does a content-hash mismatch prove?
It is evidence from the supplied extraction. A changed hash with an unchanged lastmod may indicate missed timestamp updates, while an unchanged hash with a changed lastmod may indicate broad resets. Hash equality does not prove that nothing meaningful changed.
Can this tool fetch child sitemaps listed in an index?
No. The local-only MVP resolves relationships among uploaded files and reports referenced children that were not supplied. Upload each child sitemap you want included.
Does lastmod affect rankings or guarantee recrawling?
This auditor makes no ranking, indexing, or recrawl promise. It helps teams validate whether their own lastmod implementation is internally consistent and plausibly tied to meaningful changes.
Reviewed Jul 2026 · Sources and limitations
Review details: 2026-07-13 · Marc LaClear · v1.0
Reference sources:
- Sitemaps protocol: XML format and file limits
- Google Search Central: Build and submit a sitemap
- W3C date and time formats
- MDN: Web Workers API
Known limits:
- The tool analyzes only files you supply. Sitemap-index children are not fetched from the web.
- Findings describe timestamp evidence and generator behavior; they do not prove crawling, indexing, rankings, or Google behavior.
- Equal content hashes describe only the supplied extraction and do not prove that no meaningful page change occurred.
- Date-only lastmod values retain date precision; they are not presented as second-level timestamps.
- The measured job limit is 1,000,000 URL-snapshot records, 200 MiB per compressed input, 300 MiB combined input, and 500 MiB expanded archive data.