What is MicrosoftPreview?

MicrosoftPreview is a bot in the link preview bots category, operated by Microsoft.

Bot name
MicrosoftPreview
Operator
Microsoft
Type
Bot
Respects robots.txt
Not confirmed
robots.txt user agent
MicrosoftPreview
Signs requests (Web Bot Auth)
No

About MicrosoftPreview

MicrosoftPreview generates page snapshots for Microsoft products.

Link preview bots fetch a page when someone shares its URL in a chat app or social network, to build the preview card. Blocking them breaks your link previews, so keep them allowed but leave them out of analytics and ad requests.

MicrosoftPreview user agent

MicrosoftPreview identifies itself with this user agent string:

  • Mozilla/5.0 (compatible; MicrosoftPreview/2.0; +https://aka.ms/MicrosoftPreview)

Anyone can copy a user agent string. Transfon Security also checks where each request comes from, so a request that claims to be a known crawler but comes from the wrong network is treated as a fake, not as the real crawler.

How to block MicrosoftPreview in robots.txt

We have not confirmed whether MicrosoftPreview follows robots.txt. Add a rule, then check your logs to see that it stopped. robots.txt is a plain text file at the root of your domain, such as https://example.com/robots.txt.

Block MicrosoftPreview from the whole site

User-agent: MicrosoftPreview
Disallow: /

Block MicrosoftPreview from some folders

User-agent: MicrosoftPreview
Disallow: /private/
Disallow: /search

Allow MicrosoftPreview only on some folders

User-agent: MicrosoftPreview
Allow: /blog/
Disallow: /

Allow MicrosoftPreview and block other crawlers

User-agent: MicrosoftPreview
Allow: /

User-agent: *
Disallow: /

Things to know

  • Each host needs its own file. Rules on www.example.com do not apply to shop.example.com.
  • A crawler obeys only the most specific group that names it. Once you add a User-agent: MicrosoftPreview group, MicrosoftPreview ignores your User-agent: * rules, so repeat any that should still apply.
  • The user agent name is not case sensitive. We take MicrosoftPreview from MicrosoftPreview's user agent; check Microsoft's own documentation if it publishes a different robots.txt name.
  • Crawlers cache robots.txt, so changes can take up to a day to apply. Disallow stops crawling but does not remove pages already collected or indexed.

Limits of robots.txt

  1. MicrosoftPreview may not follow the rule. robots.txt is a request that nothing enforces, and we have not confirmed that MicrosoftPreview follows it. Check your logs after adding a rule.
  2. The user agent could be fake. robots.txt matches the name a request claims. Anyone can send MicrosoftPreview's user agent, and a scraper using it is not bound by Microsoft's robots.txt policy. Only checking the source network tells a real MicrosoftPreview from a fake one.

Treat robots.txt as a statement of your policy, and enforce it where requests arrive.

Who should care about MicrosoftPreview

Publishers

MicrosoftPreview fetches pages when your links are shared or syndicated. Keep it allowed so previews and feeds work, but leave it out of page views and ad requests.

Transfon Security for publishers

Media buyers and advertisers

When ads or posts are shared, MicrosoftPreview fetches the landing page. Those hits are not clicks, so keep them out of campaign reports.

Transfon Security for advertisers

E-commerce

Product links shared in chats and feeds are fetched by MicrosoftPreview. Keep it allowed so previews show the right image and price.

Transfon Security for e-commerce

SaaS and APIs

Allow MicrosoftPreview on public pages so shared links preview well, and keep it off the app.

Transfon Security for SaaS and APIs

Block MicrosoftPreview with Transfon Security

robots.txt is a request, not an enforcement. Transfon Security shows MicrosoftPreview by name in the Top Bots report, so you can see how often it visits and which pages it reads. Block or allow it with a User Agent rule, or slow it down with a rate limit decision rule.

Transfon Security

Control MicrosoftPreview on your site

  • See every MicrosoftPreview visit and the pages it reads
  • Spot bots that fake trusted crawler names
  • Block, allow or rate limit MicrosoftPreview with one rule
  • Works with or without robots.txt support

Frequently asked questions

What is MicrosoftPreview?

MicrosoftPreview is a bot in the link preview bots category, operated by Microsoft. MicrosoftPreview generates page snapshots for Microsoft products.

Does MicrosoftPreview respect robots.txt?

We have not confirmed whether MicrosoftPreview follows robots.txt. Add a robots.txt rule, then check your logs to see that it stopped, and block it by user agent if it did not.

How do I block MicrosoftPreview?

Add "User-agent: MicrosoftPreview" followed by "Disallow: /" to the robots.txt file at the root of your site. To enforce it, block requests whose user agent contains "MicrosoftPreview/" at your WAF. In Transfon Security that is one User Agent block rule.

Is robots.txt enough to block MicrosoftPreview?

No. robots.txt is voluntary, so MicrosoftPreview may not follow it, and anyone can send MicrosoftPreview's user agent, so a fake MicrosoftPreview ignores your rule. Enforce the rule where requests arrive, at your WAF, and check the source network.

Should I block MicrosoftPreview?

Link preview bots fetch a page when someone shares its URL in a chat app or social network, to build the preview card. Blocking them breaks your link previews, so keep them allowed but leave them out of analytics and ad requests.

Related bots

All link preview bots · Full bot directory

See Which Bots Visit Your Site

Transfon Security identifies every bot in this directory in your traffic reports, flags fake search crawlers, and lets you allow, block or rate limit each bot.

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