--- url: https://findutils.com/guides/sitemap-validator title: "Validate an XML Sitemap: Find the Errors Search Engines Trip On" description: "Check sitemap.xml against the sitemaps.org protocol: well-formed XML, absolute URLs, escaped ampersands, lastmod dates and the 50,000-URL limit." category: seo content_type: guide guide_type: subtopic cluster: developer locale: en read_time: 7 status: published author: "olgunozoktas" published_at: 2026-09-26T12:00:00Z excerpt: "A sitemap can look fine in a browser and still carry an unescaped ampersand, a relative URL or a date in the wrong format. Validating it against the protocol, with a line number for every problem, finds those before a search engine reports the file as unreadable." tag_ids: ["sitemap", "seo", "xml", "crawling"] tags: ["Sitemap", "SEO", "XML", "Crawling"] primary_keyword: "xml sitemap validator" secondary_keywords: ["validate sitemap.xml", "sitemap checker", "sitemap lastmod format", "sitemap unescaped ampersand", "sitemap index validator"] tool_tag: "sitemap-validator" related_tool: "sitemap-validator" related_tools: ["sitemap-validator", "xml-sitemap-generator", "robots-txt-tester", "robots-txt-generator"] og_image: "/images/content/guides/sitemap-validator-cover-20260926.webp" image_alt: "A tree of frosted glass nodes glowing blue, with two nodes amber and one red as if flagged." updated_at: "2026-09-26T12:00:00Z" --- To validate an XML sitemap, check that it is well-formed XML, that its root is `` or `` in the sitemaps.org namespace, and that every entry has an absolute `` plus valid ``, `` and `` values within the protocol's limits. FindUtils [XML Sitemap Validator](/seo/sitemap-validator/) runs all of those checks in your browser and reports every issue with a severity, a rule name and its line number. It checks the text you paste and fetches nothing. This guide covers the rules the protocol sets, what the validator checks, a worked example, and what a valid sitemap still does not guarantee. ## Why Validate a Sitemap? A sitemap is read by software, and small mistakes make parts of it unreadable: - **An unescaped `&`** in a URL with query parameters breaks the XML. - **A relative URL** such as `/about` is not allowed; the protocol and Google both ask for absolute URLs. - **A date in the wrong format**, such as `01/09/2026`, is not a valid ``. - **A generator bug** can produce duplicate URLs, URLs from another host, or more than 50,000 entries in one file. A browser shows most of these files without complaint, which is why they ship. ## The Protocol's Rules and Limits These come from the [sitemaps.org protocol](https://www.sitemaps.org/protocol.html): | Rule | Limit or format | |---|---| | URLs per sitemap | At most 50,000 | | File size | At most 50 MB uncompressed | | Sitemap index | The same limits; up to 50,000 sitemaps | | `` | Absolute URL, less than 2,048 characters | | Encoding | UTF-8, with `&`, `<`, `>`, `"` and `'` escaped as entities | | `` | W3C Datetime; the time may be left out (`YYYY-MM-DD`) | | `` | `always`, `hourly`, `daily`, `weekly`, `monthly`, `yearly` or `never` | | `` | 0.0 to 1.0; the default is 0.5 | | Hosts | All URLs in one file from a single host | ## What Does Google Actually Use? Google's [sitemap documentation](https://developers.google.com/search/docs/crawling-indexing/sitemaps/build-sitemap) states that "Google ignores `` and `` values" and that it uses `` "if it's consistently and verifiably" accurate. So a wrong `` is still a protocol error worth fixing, but tuning priorities will not change how Google crawls. An accurate `` is the optional field worth maintaining. ## How to Validate a Sitemap ### Step 1: Paste the XML Open [XML Sitemap Validator](/seo/sitemap-validator/) and paste the sitemap or sitemap index. Use the uncompressed XML: a `.xml.gz` file must be unzipped first. ### Step 2: Read the summary The summary shows the type (`urlset` or `sitemapindex`), the number of entries, the hosts found, and the count of errors and warnings. The sitemap is valid when there are no errors. ### Step 3: Fix issues by line Each issue names its rule, its line and, where there is one, the URL. Errors break the protocol; warnings are worth a look but do not make the file invalid. ### Step 4: Validate again Fix the source, not just the file: if a generator wrote the mistake, it will write it again next time. ## A Worked Example ```xml https://example.com/2026-09-01 https://example.com/search?q=a&b=2 https://example.com/about01/09/20261.5 https://example.com/ ``` The validator reports 4 URLs, 3 errors and 1 warning, and marks the file invalid: | Line | Severity | Rule | Message | |---|---|---|---| | 4 | Error | `loc-unescaped-ampersand` | Unescaped "&" in ``; write it as `&` | | 5 | Error | `lastmod-format` | `"01/09/2026"` is not a W3C datetime | | 5 | Error | `priority-range` | `"1.5"` must be a number from 0.0 to 1.0 | | 6 | Warning | `duplicate-loc` | Duplicate ``; first listed on line 3 | The fixes: write `https://example.com/search?q=a&b=2`, write the date as `2026-09-01`, set the priority to `1.0` or remove it, and delete the repeated homepage entry. ## Everything the Validator Checks | Check | Severity | |---|---| | XML is not well-formed (stops at the first problem, with its line) | Error | | Root is neither `` nor `` | Error | | Namespace missing or not `http://www.sitemaps.org/schemas/sitemap/0.9` | Warning | | An entry with no ``, or an empty `` | Error | | `` not an absolute http(s) URL, containing whitespace, holding a bare `&`, or longer than 2,048 characters | Error | | Duplicate `` | Warning | | URLs on more than one host | Warning, once | | `` not a W3C datetime | Error | | `` more than a day in the future | Warning | | `` not one of the seven values | Error | | `` outside 0.0 to 1.0 | Error | | More than 50,000 entries | Error | | An element other than `` or `` directly inside the root | Warning | Valid `` forms are `2026`, `2026-09`, `2026-09-01`, and a date with a time and a timezone, such as `2026-09-01T10:00:00+02:00` or `2026-09-01T10:00Z`. A time with no timezone, like `2026-09-01T10:00:00`, is an error. Impossible dates such as `2026-02-29` are errors too. Image, video, news and `xhtml:link` extensions in their own namespaces are skipped, not flagged. ## Limits of the Check - **It reads up to 10 MB of XML.** The protocol allows 50 MB; validate a larger file in parts. - **It does not fetch the URLs.** A `` is checked for shape, not for a 200 response, a redirect or a `noindex`. - **It does not follow a sitemap index.** Each child sitemap has to be validated on its own. - **It does not check robots.txt.** A URL listed in the sitemap but blocked in robots.txt is a contradiction; test those paths with [robots.txt Tester](/seo/robots-txt-tester/). - **Valid is not indexed.** A clean sitemap helps discovery; it does not make a search engine index a page. ## Common Mistakes **Escaping in the CMS, not in the XML.** A URL with `&` must be written `&` inside the file, even though the real URL has a plain `&`. **Listing URLs that redirect or are blocked.** List the final, canonical URL that returns 200 and is allowed to be crawled. **Setting every lastmod to today.** Google uses `` only when it is consistently and verifiably accurate; a date that changes on every build while the page stays the same is not accurate. **Mixing hosts.** `www.example.com` and `example.com` are different hosts. Pick one. ## Use It From Code The validator is the `sitemap_validator` tool on the FindUtils REST API and MCP server. Text sent there is processed on the server rather than in your browser. ```bash curl -X POST https://api.findutils.com/api/tools/sitemap-validator/execute \ -H "Content-Type: application/json" \ -d '{"xml":"/about"}' ``` That returns `valid: false` with one `loc-not-absolute` error on line 1. The response also carries `type`, `url_count`, `hosts`, `issues` (up to 1,000) and the first 1,000 `urls`. See the [API reference](/api/sitemap-validator/) and the [MCP reference](/mcp/sitemap-validator/). ## Tools Used in This Guide | Tool | Use | |---|---| | [XML Sitemap Validator](/seo/sitemap-validator/) | Check a sitemap or sitemap index against the protocol | | [XML Sitemap Generator](/seo/xml-sitemap-generator/) | Build a sitemap from a list of URLs | | [robots.txt Tester](/seo/robots-txt-tester/) | Check that sitemap URLs are not blocked | | [Robots.txt Generator](/seo/robots-txt-generator/) | Add the Sitemap line to a new robots.txt | ## FAQ ### How many URLs can a sitemap have? At most 50,000 URLs and 50 MB uncompressed per file. For more, split the URLs into several sitemaps and list them in a sitemap index. ### What date format does lastmod use? W3C Datetime: `YYYY-MM-DD`, or a full date and time with a timezone, such as `2026-09-01T10:00:00+02:00`. ### Does Google use changefreq and priority? No. Google's documentation states that it ignores both. It uses `` when the dates are consistently accurate. ### Does the validator check that my URLs work? No. It checks the XML and the shape of each URL but fetches nothing, so a URL that returns 404 is not detected. ### Can it validate a gzipped sitemap? Not directly. Unzip the `.xml.gz` file and paste the XML. ## Next Steps Check your file with [XML Sitemap Validator](/seo/sitemap-validator/). To build one from scratch, use the [XML Sitemap Generator](/seo/xml-sitemap-generator/) and read its [guide](/guides/xml-sitemap-generator-guide/).