Part of the SiteMap Series
Up to this point, every sitemap you have seen in this series has been XML. Module 1 covered XML sitemap fundamentals. Module 2 covered building, submitting, validating, and maintaining XML sitemaps. The first five lessons of Module 3 covered XML sitemap extensions for images, video, news, and hreflang. XML is the format with the most flexibility, the most search engine support, and the richest metadata capability, which is why it has been the focus.
XML is not the only format search engines accept, though. RSS feeds, Atom feeds, and plain text URL lists can all be submitted as sitemaps in certain situations. mRSS (Media RSS) existed historically as an extension for media content. Each has a narrower use case than XML, but they show up in practical scenarios often enough to be worth understanding.
This lesson covers the format hierarchy (why XML stays the primary recommendation), when RSS or Atom feeds can supplement your sitemap strategy, when a plain text URL list makes sense, why mRSS is no longer worth using, how to submit non-XML sitemaps to search engines, and the gotchas that come with formats outside the XML standard.
The format hierarchy for sitemap submission
The four formats search engines accept for sitemap submission are not equivalent. They serve different purposes, expose different metadata, and have different practical strengths.
1. XML sitemap (sitemap.xml)
The standard format. Supports lastmod, priority (deprecated for ranking but still parsed), changefreq (also deprecated for ranking), and all the namespace extensions covered earlier in this module (image, video, news, hreflang). The recommended format for nearly every site.
2. RSS 2.0 and Atom 1.0 feeds
Designed for content syndication rather than sitemap submission, but accepted by search engines as sitemaps when the feed lists URLs the engines can crawl. Typically shows only recent items (most feeds expose the last 10 to 20 entries) rather than the full site. Useful for signalling fresh content.
3. Plain text URL lists
A .txt file with one URL per line, UTF-8 encoded. The simplest possible format. No metadata, no extensions, no structure beyond the URLs themselves. Used to be more common before XML sitemaps became universal; now mainly relevant for one-off bulk submissions or unusual workflows.
4. mRSS (Media RSS)
An extension of RSS designed for media content (audio, video, images). Effectively superseded by XML sitemap extensions for video and image. Mentioned here because older documentation still references it; not recommended for new implementations.
The practical hierarchy: XML for everything by default, RSS or Atom to supplement when you have an existing feed and want to signal fresh content quickly, plain text for narrow cases, mRSS for nothing.
RSS and Atom feeds as supplementary sitemaps
If your site already publishes an RSS or Atom feed (most WordPress sites do, automatically), the engines accept that feed URL as a sitemap submission. The feed becomes a freshness signal: a fast way to tell the engines about new content as soon as it goes live.
WordPress generates two feeds by default. The RSS feed lives at /feed/ (for example, https://example.com/feed/). The Atom feed lives at /feed/atom/. Both are automatic; no plugin needed.
The strength of feed-based sitemap submission is freshness. Most feed implementations include only the most recent items, which means the feed is small and the engines can process it quickly. For sites that publish frequently, submitting the feed alongside the XML sitemap accelerates discovery of new content.
The weakness is coverage. A typical RSS feed exposes the last 10 to 20 items. Older content is not in the feed and gets no signal from this submission. That means feed-based submission cannot replace XML sitemap submission for full-site coverage; it can only supplement it.
A reasonable workflow for content-heavy sites: submit the XML sitemap for full-site coverage and submit the RSS or Atom feed as a supplementary fresh-content signal. The engines treat them as separate sitemaps in Search Console and report on them independently.
For sites that do not publish frequently or that already have a well-maintained XML sitemap with accurate lastmod values, the feed supplement adds little. The freshness signal from XML lastmod is usually sufficient when it is being kept current.
Plain text URL lists for narrow scenarios
A plain text URL list is exactly what it sounds like: a .txt file with one URL per line, UTF-8 encoded. No XML, no metadata, no structure beyond the URLs themselves. The example structure:
https://example.com/page-1/
https://example.com/page-2/
https://example.com/page-3/
https://example.com/page-4/
The same 50,000 URL and 50MB file size limits that apply to XML sitemaps also apply to plain text sitemaps.
Plain text URL lists have three legitimate use cases.
- Bulk submission during a migration. When a site migration produces a list of new URLs that needs to be submitted quickly, exporting the URL list as a plain text file is faster than generating a full XML sitemap with metadata you do not yet have.
- Quick supplementary submissions. A new content section, a batch of newly published pages, or a temporary collection that warrants explicit indexing attention. A short plain text file can be submitted alongside the main XML sitemap as a focused signal.
- Sites with no metadata to add. Some sites genuinely have no useful lastmod, priority, or changefreq information to include. In those rare cases, plain text is no worse than XML with empty or fabricated metadata.
For everything else, plain text loses to XML because XML carries metadata that helps the engines, while plain text does not. New sitemap implementations should default to XML; plain text is a tool for specific scenarios, not a general-purpose alternative.
Why mRSS is no longer worth using
Media RSS (mRSS) is an extension of RSS designed to carry media metadata (video URLs, audio URLs, thumbnails, durations, content ratings). It was used as a video sitemap format before the XML video sitemap extension matured.
The XML video sitemap extension covered in Lesson 3: How to Create a Video Sitemap replaced mRSS for almost all practical purposes. The XML video sitemap is more flexible, better documented, and more widely supported. Search engines still parse mRSS when they encounter it, but they do not recommend it for new implementations.
If you have an existing mRSS feed (perhaps from a legacy video platform), it will continue to work. If you are building video sitemap support from scratch, use the XML video sitemap extension instead. mRSS is mentioned here only because older Technical SEO documentation sometimes references it, and you may encounter it in legacy systems.
How to submit non-XML sitemaps to search engines
Submission for non-XML sitemaps works the same way as for XML sitemaps. The submission process from Lesson 7 of Module 2: How to Submit Your Website Sitemap to Google Search Console applies; you just paste the non-XML sitemap URL instead of the XML one.
A few format-specific considerations.
RSS or Atom feed submission. Paste the feed URL (commonly /feed/ or /feed/atom/ on WordPress) into the Sitemaps section of Search Console. The engines treat the feed as a sitemap from that point onward. You can submit the same feed to Bing Webmaster Tools through the equivalent submission interface.
Plain text URL list submission. Host the .txt file on your domain (typically at /sitemap.txt or /urls.txt) and submit the URL through Search Console. Make sure the file is served with a Content-Type: text/plain header, not as application/octet-stream or a download attachment.
Multiple sitemaps including non-XML. You can submit XML, RSS, and plain text sitemaps to the same Search Console property simultaneously. Search Console will report on each separately. This is the normal workflow for sites that supplement XML with feed-based freshness signals.
For validation, the standard validation approach from Module 2 applies: check that the file returns 200 status, parses correctly, and shows up in Search Console’s Sitemaps report without errors. Non-XML formats have fewer validation tools than XML (Screaming Frog parses XML sitemaps natively but treats plain text files as simple URL lists), so manual verification matters more.
Common gotchas to avoid
Four issues come up regularly with non-XML sitemap formats.
1. Treating an RSS feed as a full sitemap replacement
The most common mistake. RSS feeds typically expose 10 to 20 recent items, not the entire site. Submitting only the feed without an accompanying XML sitemap leaves older content with no sitemap signal. The fix is to treat RSS as supplementary, not primary.
2. Plain text files served with the wrong Content-Type
A .txt file served with Content-Type: application/octet-stream (which triggers a browser download) does not work as a sitemap because the engines treat it as binary. The fix is to configure the server to serve .txt files with Content-Type: text/plain; charset=utf-8. On Apache, an AddType directive handles it; on Nginx, the default mime types configuration usually covers it.
3. Submitting an mRSS feed for video content instead of an XML video sitemap
mRSS works but lacks the flexibility and structured metadata of the XML video sitemap extension. New implementations should use XML even when mRSS would technically be accepted. The fix is to move to the XML video sitemap as covered in Lesson 3, and retire the mRSS feed if it exists.
4. Non-UTF-8 encoding in plain text files
Plain text sitemaps must be UTF-8 encoded. Files saved in Windows-1252, Latin-1, or other encodings can cause URLs with international characters to be misinterpreted. The fix is to explicitly save the file as UTF-8 in your text editor or build process.
Where this leaves us
You now have full coverage of the sitemap format landscape: XML as the primary format with its standard structure and four namespace extensions, plus the alternative formats (RSS, Atom, plain text) that supplement XML in specific scenarios. Most sites will use XML exclusively. Sites that publish frequently may add RSS or Atom for freshness signals. A small minority will use plain text for specific workflows.
The final lesson of Module 3 ties the four specialised sitemap types together with a strategic question: when should specialised sitemaps be combined into a single sitemap file, and when should they be separated into distinct files referenced by a sitemap index? The decision depends on site size, content type mix, update frequency, and validation requirements. There are sensible default patterns and clear failure modes to avoid.
Up next: When to Combine or Separate Specialised Sitemaps →
This is Module 3: Lesson 6 of The Sitemap Series, a technical SEO series on sitemaps from first principles, built for the AI Search era.