Safe Official docs Search Engines

Microsoft Preview

Operated by Microsoft

Quick Facts

User-Agent:
MicrosoftPreview
Category:
Search Engines
Operator:
Microsoft
Safety:
Safe
Blocking Impact:
Low - No SEO ranking impact
SEO Impact Score:
2/10
Official docs:
www.bing.com

Confirmed by the operator

Microsoft names MicrosoftPreview on its own documentation page, linked above. The token, purpose and robots.txt behaviour on this profile come from that page, re-checked on October 19, 2026.

What is Microsoft Preview?

Microsoft Preview is an AI crawler operated by Microsoft. It uses the user-agent string MicrosoftPreview and follows the Robots Exclusion Protocol.

Microsoft Preview is an AI crawler operated by Microsoft. It uses the user-agent string MicrosoftPreview and follows the Robots Exclusion Protocol.
Microsoft Preview uses the user-agent token MicrosoftPreview. You can control it via robots.txt, meta tags (noai), or the emerging llms.txt standard. Robots.txt is voluntary; for hard enforcement, combine it with server-level IP blocking.

What happens if you block Microsoft Preview?

🔶 AI Visibility Trade-off - Blocking Microsoft Preview will not hurt Google or Bing rankings, but it can remove your content from AI search answers and assistant citations powered by this crawler. Block only if you have a deliberate reason.
Generally safe to allow; provides legitimate crawling value.

How to block Microsoft Preview with robots.txt

<code>User-agent: MicrosoftPreview</code> - Matching is case-insensitive. Robots.txt is fetched from the root of each subdomain separately.

Block completely (robots.txt)
User-agent: MicrosoftPreview Disallow: /
Allow all (robots.txt)
User-agent: MicrosoftPreview Allow: /
Block private only (robots.txt)
User-agent: MicrosoftPreview Disallow: /private/ Disallow: /api/ Disallow: /admin/ Allow: /
Nginx server block
# Nginx: Hard-block Microsoft Preview if ($http_user_agent ~* "MicrosoftPreview") { return 403 "Bot blocked"; }
Apache .htaccess
# Apache: Hard-block Microsoft Preview SetEnvIfNoCase User-Agent "MicrosoftPreview" bad_bot Order Allow,Deny Allow from all Deny from env=bad_bot
Meta robots tag
<meta name="robots" content="noindex, nofollow">
X-Robots-Tag header
X-Robots-Tag: noindex, nofollow

Is Microsoft Preview safe to allow?

Yes, Microsoft Preview is a safe and legitimate crawler operated by Microsoft. It follows the Robots Exclusion Protocol (RFC 9309) and can be controlled with standard robots.txt rules.
Verify by reverse-DNS lookup: legitimate Microsoft Preview requests resolve to Microsoft's domain.

What does Microsoft Preview do?

Understanding Microsoft Preview's purpose helps you decide whether to allow or block it.

  • Indexes web pages for AI-powered search answers
  • Surfaces your content as citations inside AI search results
  • Builds a knowledge index used to answer user questions
  • Allowing it can increase visibility in AI search
  • Respects robots.txt directives

Microsoft Preview in context

Microsoft Preview is a utility crawler operated by Microsoft. In plain terms, it fetches a page to build a link preview when someone shares it. Our database files it under search engines and ranks it Tier 3, mid-priority crawlers with a clear purpose but a smaller audience. 62 of the 63 search engines in our database share this tier.

Its safety rating is safe and its blocking impact is not documented. So the decision about Microsoft Preview rests on what you want from Microsoft, not on its behaviour. How we rate safety and impact.

How site owners treat Microsoft Preview

Our robots.txt study of the Tranco top 10,000 did not track MicrosoftPreview as a named token, so we do not publish an adoption figure for it. If you run a large site, your own logs are the best evidence of how often it visits.

Does it follow robots.txt?

Microsoft Preview's operator does not clearly document how it treats robots.txt. Write the Microsoft Preview rule anyway, then confirm in your logs that its requests stop.

Microsoft crawlers and close alternatives

Microsoft Preview is one of 6 Microsoft crawlers in our database. A User-agent: MicrosoftPreview group controls Microsoft Preview only; the other Microsoft tokens below need their own lines.

  • MicrosoftPreview: this crawler (Tier 3)
  • AdIdxBot: Bing Ads Crawler, checks pages for an SEO, uptime or analytics service (Tier 3)
  • AzureAI-SearchBot: Azure AI Search, builds a search or answer index (Tier 2)
  • bingbot: Bing Search, builds a search or answer index (Tier 3)
  • BingPreview: Bing Page Snapshot, builds a search or answer index (Tier 3)
  • BingVideoPreview: Bing Video Preview, builds a search or answer index (Tier 3)

To give Microsoft Preview the same answer as its siblings, stack User-agent: MicrosoftPreview with their lines above one set of rules; to treat Microsoft Preview differently, give it its own group.

No other crawler in our search engines category has exactly the same purpose, which makes Microsoft Preview an unusual case: decide about it on its own merits.

We first recorded MicrosoftPreview on September 22, 2026. Microsoft documents it on bing.com, and we recheck that page before each release.

Which rule Microsoft Preview actually follows

Microsoft Preview reads exactly one group in robots.txt, the most specific one that names MicrosoftPreview, and never combines rules across groups. This short file shows the trap:

User-agent: *
Disallow: /private/

User-agent: MicrosoftPreview
Disallow: /drafts/
  1. Find the group. Microsoft Preview looks for a group naming MicrosoftPreview. One exists, so it ignores User-agent: * completely.
  2. Apply only that group. It is refused /drafts/ and nothing else.
  3. The surprise. /private/ is open to Microsoft Preview, because that rule lives in the * group it no longer reads. To keep it out of both, repeat Disallow: /private/ inside its own group.
Test yourself: does a rule under User-agent: * apply to Microsoft Preview if the file also has a User-agent: MicrosoftPreview group?

No. Once a group names it, Microsoft Preview reads only that group. Put every rule you want it to follow inside its own group.

Related: how AI engines choose their sources

Test yourself: will blocking Microsoft Preview remove your pages from AI answers?

Often, yes. Microsoft Preview is a utility crawler, so pages it cannot fetch can drop out of the answers or results it supports.

Test yourself: is User-agent: microsoftpreview the same as User-agent: MicrosoftPreview?

Yes. RFC 9309 makes user-agent matching case-insensitive. Paths are a different story: Disallow: /Blog/ does not block /blog/.

Should you allow Microsoft Preview? Decide by situation

Recommended setting for Microsoft Preview by type of site
If you are...Recommended setting
You publish content and want AI answers to cite itLow stakes either way. It does not decide whether AI answers cite you.
You license content and want to stop AI trainingBlocking it does not stop training, because Microsoft Preview is a utility crawler. Block the operator's training crawler instead.
You run an online shopAllow it unless it is overloading your servers.
Your server is under load from botsRate-limit before blocking. It is rated safe in our database.

Check Microsoft Preview on your own site

  1. Open /robots.txt on your domain and search for MicrosoftPreview. If it is not named, it follows User-agent: *.
  2. List the Disallow lines in the group Microsoft Preview follows and test your key URLs against them; the longest match wins, and Allow wins a tie.
  3. Look beyond the file. A firewall or bot manager can refuse Microsoft Preview even when robots.txt allows it, and that never shows in the file.
  4. Run our AI crawler tester to see how Microsoft Preview and every other crawler we track are treated in one pass, including firewall refusals.

Common mistakes with Microsoft Preview

The errors we see most often with Microsoft Preview in the files and firewalls we test:

  1. Treating Microsoft Preview as an AI or search crawler. Blocking it has little effect on visibility; decide based on load and what it does with your data.
  2. Relying on robots.txt alone when Microsoft Preview is rated caution or aggressive. Back the rule with a server-side block.
  3. Blocking Microsoft Preview by IP alone. Ranges change; match the token and verify with logs.

All three hide inside a file that looks correct, so check Microsoft Preview from outside after every change.

Spotting Microsoft Preview in your logs

robots.txt says what Microsoft Preview may do; your access logs show what it actually did.

Count requests

On a server with standard Nginx or Apache logs, this counts matching requests per day (adjust the log path for your host):

grep -iE "MicrosoftPreview" /var/log/nginx/access.log \
  | awk '{print $4}' | cut -d: -f1 | sort | uniq -c

And this shows which paths it requested most, which is the quickest way to see whether your Disallow lines are being respected:

grep -iE "MicrosoftPreview" /var/log/nginx/access.log \
  | awk '{print $7}' | sort | uniq -c | sort -rn | head -20

Check the requests are genuine

Anyone can send the Microsoft Preview user-agent, so confirm the source before acting on a match:

  • MicrosoftPreview: we hold no published IP list, so use reverse DNS where the operator documents a hostname and treat an unverifiable Microsoft Preview request with caution.

Frequently Asked Questions

What is the official user-agent string for Microsoft Preview?
The official user-agent string for Microsoft Preview is: MicrosoftPreview. Use this exact string in robots.txt, Nginx, Apache, or Cloudflare firewall rules to target this bot. Matching in robots.txt is case-insensitive. Verify a request genuinely comes from Microsoft Preview by performing a reverse-DNS lookup on the source IP.
Is Microsoft Preview safe?
Yes, Microsoft Preview is a safe and legitimate crawler operated by Microsoft. It follows the Robots Exclusion Protocol (RFC 9309) and can be controlled with standard robots.txt rules.
Will blocking Microsoft Preview hurt my SEO?
🔶 AI Visibility Trade-off - Blocking Microsoft Preview will not hurt Google or Bing rankings, but it can remove your content from AI search answers and assistant citations powered by this crawler. Block only if you have a deliberate reason.
How do I block Microsoft Preview in robots.txt?
Add the following lines to your /robots.txt file:
User-agent: MicrosoftPreview
Disallow: /

This instructs Microsoft Preview not to crawl any path on your site. To block only specific sections, replace / with the path (e.g., Disallow: /blog/).
Does Microsoft Preview respect robots.txt?
Microsoft Preview is operated by Microsoft and is expected to fetch and parse /robots.txt before crawling, following RFC 9309. For hard enforcement, combine robots.txt with server-level IP or user-agent blocking.
How do I verify if Microsoft Preview is crawling my site?
Search your web server access logs for the string MicrosoftPreview (case-insensitive: grep -i "MicrosoftPreview" /var/log/nginx/access.log). Filter by user-agent in your log analytics tool (GoAccess, AWStats, etc.).

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