Slack

Common mistakes with Slack's crawlers

The errors we see most often with Slack's crawlers in the files and firewalls we test:

1. Treating Slack's crawlers 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 Slack's crawlers is rated caution or aggressive. Back the rule with a server-side block.
3. Blocking Slack's crawlers by IP alone. Ranges change; match the token and verify with logs.

All three hide inside a file that looks correct, so check Slack's crawlers from outside after every change.

Spotting Slack in your logs

robots.txt says what Slack Link Expander and Slackbot may do; your access logs show what they 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 "Slackbot-LinkExpanding|Slackbot" /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 "Slackbot-LinkExpanding|Slackbot" /var/log/nginx/access.log \
  | awk '{print $7}' | sort | uniq -c | sort -rn | head -20

Check the requests are genuine

Anyone can send these user-agents, so confirm the source before acting on a match:

• Slackbot-LinkExpanding: we hold no published IP list, so use reverse DNS where Slack documents a hostname and treat an unverifiable Slack Link Expander request with caution. Check it separately from Slackbot.
• Slackbot: we hold no published IP list, so use reverse DNS where Slack documents a hostname and treat an unverifiable Slackbot request with caution. Check it separately from Slack Link Expander.

What our own data shows about Slack

Everything below comes from the AI Crawler Check bot database and our two most recent robots.txt scans of the Tranco top 10,000, not from Slack's marketing. It covers 2 Slack tokens in turn.

Slackbot-LinkExpanding in our records

We first recorded Slackbot-LinkExpanding on September 22, 2026. Slack documents it on api.slack.com, and we recheck that page before each release. No file in our top-10,000 scans names Slackbot-LinkExpanding, so any rule you write for it puts you ahead of almost every large site.

Among the 9 social preview bots in our database, Slackbot-LinkExpanding sits eighth by priority (Tier 5), level with FacebookBot, facebookexternalhit, LinkedInBot, Pinterestbot. 9 of the 9 share its safe rating. Other operators with a crawler that fetches a page to build a link preview when someone shares it: MicrosoftPreview (Microsoft, Tier 3), FacebookBot (Meta, Tier 5), facebookexternalhit (Meta, Tier 5), GoogleMessages (Google, Tier 5), LinkedInBot (LinkedIn, Tier 5). A policy for Slackbot-LinkExpanding is usually a policy for these too.

A decision record for Slackbot-LinkExpanding

Teams that review crawlers once a quarter keep one short entry per token, so anyone can see why a rule exists and when it was last checked. Filled in from our data, the Slackbot-LinkExpanding entry reads:

• Operator and job: Slack; it fetches a page to build a link preview when someone shares it.
• Priority and behaviour: Tier 5, rated safe, blocking impact not documented.
• Suggested starting point: Allow by default; revisit if it costs you bandwidth.
• Enforcement: Slackbot-LinkExpanding's operator does not clearly document how it treats robots.txt. Write the Slackbot-LinkExpanding rule anyway, then confirm in your logs that its requests stop.

User-agent: Slackbot-LinkExpanding
Allow: /

Paste the line into the validator with one of your own URLs before it goes live. Revisit the Slackbot-LinkExpanding entry once a quarter, or when Slack publishes a new token next to it.

Slackbot in our records

We first recorded Slackbot on March 17, 2026. Slack documents it on api.slack.com, and we recheck that page before each release. No file in our top-10,000 scans names Slackbot, so any rule you write for it puts you ahead of almost every large site.

Among the 9 social preview bots in our database, Slackbot sits seventh by priority (Tier 5), level with FacebookBot, facebookexternalhit, LinkedInBot, Pinterestbot. 9 of the 9 share its safe rating. Other operators with a crawler that fetches a page to build a link preview when someone shares it: MicrosoftPreview (Microsoft, Tier 3), FacebookBot (Meta, Tier 5), facebookexternalhit (Meta, Tier 5), GoogleMessages (Google, Tier 5), LinkedInBot (LinkedIn, Tier 5). A policy for Slackbot is usually a policy for these too.

A decision record for Slackbot

Teams that review crawlers once a quarter keep one short entry per token, so anyone can see why a rule exists and when it was last checked. Filled in from our data, the Slackbot entry reads:

• Operator and job: Slack; it fetches a page to build a link preview when someone shares it.
• Priority and behaviour: Tier 5, rated safe, blocking impact not documented.
• Suggested starting point: Allow by default; revisit if it costs you bandwidth.
• Enforcement: Slackbot's operator does not clearly document how it treats robots.txt. Write the Slackbot rule anyway, then confirm in your logs that its requests stop.

User-agent: Slackbot
Allow: /

Paste the line into the validator with one of your own URLs before it goes live. Revisit the Slackbot entry once a quarter, or when Slack publishes a new token next to it.

How top sites treat Slack's crawlers

From our robots.txt study of the Tranco top 10,000 (5,583 valid files, fetched October 20, 2026):

None of the tokens for Slack's crawlers is tracked by name in our study. For scale, 20.1% of top-site files block at least one AI training crawler and 4.3% refuse every unnamed crawler with User-agent: * and Disallow: /, which would catch Slack's crawlers too.

More questions about Slack

Will blocking Slack affect my Google rankings?

Only if one of its tokens is a Google search crawler. None of Slack's tokens are Googlebot, so classic Google rankings are unaffected.

How quickly does a robots.txt change take effect for Slack?

Crawlers cache robots.txt, commonly for up to a day. Expect a change to apply within about 24 hours, and confirm it in your logs.

Can I allow Slack on some sections and block it on others?

Yes. Inside the group for Slackbot-LinkExpanding, add Disallow lines for the paths to keep private and Allow lines for exceptions. The longest matching rule wins.

Does blocking Slack delete content it already collected?

No. robots.txt only controls future visits. For content already collected, check whether Slack offers a removal or opt-out process.

Is a firewall block better than robots.txt for Slack?

A firewall enforces the decision, while robots.txt asks politely. Many operators recommend robots.txt because blocking their IPs can stop them reading your rules at all. Use robots.txt first, and add a firewall rule only if requests continue.