Bot signals · Web crawler

What is SemrushBot-SI?

Semrush On Page SEO Checker (SemrushBot-SI)

SemrushBot-SI is the Semrush bot that crawls pages for Semrush’s On Page SEO Checker and similar tools, which give optimisation ideas for the pages a Semrush user tracks.

risk.is_crawler

Official documentation All web crawlers

01 · Profile

SemrushBot-SI at a glance.

What to look for in your logs, and what the lookup API returns for its addresses.

Type: Web crawler
User agent: SemrushBot-SI
robots.txt: User-agent: SemrushBot-SI
API flag: risk.is_crawler

A user agent alone never sets a flag. Anyone can claim to be SemrushBot-SI; the flag follows the address the request comes from.

02 · In the response

What a match looks like.

A lookup of a SemrushBot-SI address sets risk.is_crawler. The flags come with geolocation and network data in the same response, for API keys on every paid plan.

The response says which kind of bot an address belongs to, not which operator. A request that claims to be SemrushBot-SI while risk.is_crawler is false should not be trusted as SemrushBot-SI.

GET /api/lookup/{ip}?key=YOUR_API_KEY

{
  // … location and network fields …
  "risk": {
    "is_ai": false,
    "is_crawler": true,
    "is_scanner": false
  }
}

03 · Control

Allow or block SemrushBot-SI.

robots.txt

User-agent: SemrushBot-SI
Disallow: /

Semrush documents disallowing SemrushBot-SI in robots.txt to block it from the On Page SEO Checker and similar tools. The On Page SEO Checker only accepts a crawl-delay of 1 second and skips pages with a higher value.

To enforce it

robots.txt is a request. Well-behaved bots follow it; impostors using its name don’t.
Firewall, WAF or CDN. Many offer bot rules you can allow or deny by category. Use them to enforce what robots.txt only asks for.
In your app. Look up the client address and allow or deny on risk.is_crawler, alongside the user agent.
Never on the user agent alone. Blocking the name stops only honest clients; allowing it lets anyone in who borrows it.