Crawler List: Web Crawler Bots - Complete Guide to Internet Bots

Every second, thousands of bots are crawling websites around the world. Right now, as you read this, multiple bots are probably scanning your website, indexing content, checking prices, or analyzing data. Studies show that bots account for approximately 42% of all internet traffic – nearly half of all web activity isn’t human at all. Yet most website owners couldn’t name more than two or three of these digital visitors.

Understanding which bots visit your site, what they do, and whether to allow them is crucial for website performance, SEO success, and security. Some bots are essential for your online visibility, others provide valuable services, and some might be draining your resources or scraping your content without permission. This comprehensive guide identifies all major web crawlers, explains their purposes, and helps you make informed decisions about bot traffic.

Understanding Web Crawlers: The Basics

Before diving into specific crawlers, it’s important to understand what these bots actually do and why they exist.

What Web Crawlers Do:

Systematically browse the internet
Index content for search engines
Monitor website changes
Collect data for various purposes
Check website health and performance
Verify security and compliance

How Crawlers Identify Themselves: Every legitimate crawler identifies itself through a User-Agent string – like a digital business card that tells your server who’s visiting. For example:

Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)
Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)

Why This Matters for Your Website:

SEO depends on search engine crawlers
Server resources get consumed by bot traffic
Some bots respect robots.txt, others don’t
Blocking wrong bots can hurt your visibility
Allowing wrong bots can hurt your business

Part 1: Search Engine Crawlers

These are the most important bots for most websites. Without them, you won’t appear in search results.

Googlebot

Purpose: Indexes content for Google Search

User-Agent Strings:

Main crawler: Googlebot/2.1 (+http://www.google.com/bot.html)
Image crawler: Googlebot-Image/1.0
Video crawler: Googlebot-Video/1.0
News crawler: Googlebot-News
Mobile crawler: Googlebot-Mobile/2.1

Behavior Characteristics:

Visits frequently (daily to monthly depending on site)
Respects robots.txt strictly
Follows sitemaps
Renders JavaScript
Crawls from multiple IP ranges

What It Looks For:

New and updated content
Site structure and internal links
Mobile compatibility
Page speed signals
Structured data

How to Optimize for Googlebot:

Submit sitemap via Google Search Console
Ensure fast page load times
Fix crawl errors immediately
Use structured data markup
Maintain consistent URL structure

Should You Allow It? Yes, unless you don’t want Google traffic (extremely rare)

Bingbot

Purpose: Indexes content for Microsoft Bing

User-Agent Strings:

Main: Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)
Preview: Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53 (compatible; bingbot/2.0)

Behavior Characteristics:

Less frequent than Googlebot
Also powers Yahoo search results
Renders JavaScript
Respects crawl-delay directive
Can be more aggressive than Googlebot

Unique Features:

Powers Cortana responses
Indexes for Microsoft ecosystem
Feeds DuckDuckGo results partially

Optimization Tips:

Submit to Bing Webmaster Tools
Use IndexNow protocol for instant indexing
Ensure proper schema markup
Monitor crawl stats in Bing Webmaster Tools

Should You Allow It? Yes, it’s the second-largest search engine

Yandex Bot

Purpose: Indexes content for Yandex (Russia’s largest search engine)

User-Agent Strings:

Main: Mozilla/5.0 (compatible; YandexBot/3.0; +http://yandex.com/bots)
Images: Mozilla/5.0 (compatible; YandexImages/3.0; +http://yandex.com/bots)
Video: Mozilla/5.0 (compatible; YandexVideo/3.0; +http://yandex.com/bots)

Behavior Characteristics:

Important for Russian-speaking markets
Can be resource-intensive
Respects robots.txt
Supports Clean-param directive
Crawls from Russian IP addresses primarily

Regional Importance:

60% market share in Russia
Popular in Belarus, Kazakhstan, Turkey
Growing in Eastern Europe

Should You Allow It? Yes if you have international audience, optional for US-only sites

Baidu Spider

Purpose: Indexes content for Baidu (China’s dominant search engine)

User-Agent Strings:

Main: Baiduspider/2.0; +http://www.baidu.com/search/spider.html
Image: Baiduspider-image+(+http://www.baidu.com/search/spider.htm)
Mobile: Mozilla/5.0 (compatible; Baiduspider/2.0; +http://www.baidu.com/search/spider.html)

Behavior Characteristics:

Essential for Chinese market
Can be very aggressive
Sometimes ignores crawl-delay
Crawls from Chinese IP ranges
May not respect robots.txt fully

Challenges:

Language barriers in documentation
Can overwhelm small servers
Limited support outside China

Should You Allow It? Yes if targeting Chinese market, consider blocking if not

DuckDuckGo Bot

Purpose: Indexes content for DuckDuckGo search

User-Agent String:

DuckDuckBot/1.0; (+http://duckduckgo.com/duckduckbot.html)

Behavior Characteristics:

Less frequent crawling
Privacy-focused
Respects robots.txt
Also uses Bing results
Lightweight crawler

Should You Allow It? Yes, growing privacy-conscious user base

Seznam Bot

Purpose: Indexes for Seznam (Czech Republic’s search engine)

User-Agent String:

Mozilla/5.0 (compatible; SeznamBot/4.0; +http://napoveda.seznam.cz/en/seznambot-intro/)

Behavior Characteristics:

Important for Czech market
Moderate crawl rate
Respects robots.txt
Good documentation

Should You Allow It? Yes if targeting Czech Republic/Slovakia

Part 2: Social Media Crawlers

These bots generate link previews when URLs are shared on social platforms.

Facebook Crawler (facebookexternalhit)

Purpose: Creates link previews for Facebook, Instagram, WhatsApp

User-Agent Strings:

facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)
facebookcatalog/1.0
WhatsApp: WhatsApp/2.19.81 A

Behavior Characteristics:

Crawls when URL first shared
Re-crawls when explicitly requested
Caches previews aggressively
Respects Open Graph tags
Can cause traffic spikes

What It Extracts:

Open Graph meta tags
Title and description
Images (prefers 1200x630px)
Video information
Article metadata

Optimization Tips:

Use Open Graph tags properly
Provide high-quality preview images
Test with Facebook Sharing Debugger
Implement caching for crawler requests

Should You Allow It? Yes, essential for social sharing

Twitter Bot (Twitterbot)

Purpose: Creates Twitter Card previews

User-Agent String:

Twitterbot/1.0

Behavior Characteristics:

Crawls on first tweet
Caches for ~7 days
Respects Twitter Card tags
Lightweight crawler
Returns for updates periodically

Twitter Card Types:

Summary Card
Summary Card with Large Image
Player Card
App Card

Should You Allow It? Yes, improves tweet engagement

LinkedIn Bot

Purpose: Generates link previews for LinkedIn posts

User-Agent String:

LinkedInBot/1.0 (compatible; Mozilla/5.0; Apache-HttpClient +http://www.linkedin.com)

Behavior Characteristics:

Professional network focused
Respects Open Graph tags
Caches previews
Can be blocked without major impact

Should You Allow It? Yes for B2B sites, optional for others

Pinterest Bot

Purpose: Creates Rich Pins and validates content

User-Agent String:

Pinterest/0.2 (+http://www.pinterest.com/bot.html)

Behavior Characteristics:

Crawls for Rich Pin validation
Respects robots.txt
Important for e-commerce
Re-crawls periodically

Should You Allow It? Yes for e-commerce and lifestyle sites

Telegram Bot

Purpose: Creates link previews in Telegram messages

User-Agent String:

TelegramBot (like TwitterBot)

Behavior Characteristics:

Instant preview generation
Respects Open Graph tags
Growing platform
Lightweight

Should You Allow It? Yes, increasingly important messenger

Part 3: SEO and Analysis Bots

These bots help with SEO analysis and competitive research.

Ahrefs Bot

Purpose: Builds backlink database for Ahrefs SEO tool

User-Agent String:

Mozilla/5.0 (compatible; AhrefsBot/7.0; +http://ahrefs.com/robot/)

Behavior Characteristics:

Very active crawler
Can be resource-intensive
Respects robots.txt
Crawls for backlink data
Used by SEO professionals

Data Collected:

Backlink profiles
Anchor text
Page content
Site structure

Should You Allow It? Depends on whether you want competitors analyzing your backlinks

Semrush Bot

Purpose: Collects data for Semrush SEO platform

User-Agent String:

Mozilla/5.0 (compatible; SemrushBot/7~bl; +http://www.semrush.com/bot.html)

Behavior Characteristics:

Regular crawling
Respects robots.txt
Multiple bot variants
Can be aggressive

Variants:

SemrushBot-SA (Site Audit)
SemrushBot-BA (Backlink Audit)
SemrushBot-BM (Brand Monitoring)

Should You Allow It? Your choice – blocking limits competitor research but also your own

Moz Bot (Rogerbot/Dotbot)

Purpose: Indexes for Moz’s Link Explorer

User-Agent Strings:

rogerbot/1.0 (http://moz.com/help/pro/rogerbot-crawler)
Mozilla/5.0 (compatible; DotBot/1.2; +https://opensiteexplorer.org/dotbot)

Behavior Characteristics:

Moderate crawl rate
Respects robots.txt
Professional SEO tool
Less aggressive than others

Should You Allow It? Optional – depends on competitive concerns

Majestic Bot (MJ12bot)

Purpose: Maps the web for Majestic SEO tool

User-Agent String:

Mozilla/5.0 (compatible; MJ12bot/v1.4.8; http://mj12bot.com/)

Behavior Characteristics:

Can be very aggressive
Distributed crawler
Respects robots.txt (usually)
Resource-intensive

Common Complaints:

High server load
Frequent crawling
Sometimes ignores crawl-delay

Should You Allow It? Often blocked due to aggressive behavior

Screaming Frog SEO Spider

Purpose: Desktop-based SEO crawler for site audits

User-Agent String:

Screaming Frog SEO Spider/16.0

Behavior Characteristics:

Controlled by user
One-time crawls usually
Used for technical SEO audits
Can crawl entire site quickly

Should You Allow It? Yes, usually legitimate SEO work

Part 4: Monitoring and Performance Bots

These bots check website availability and performance.

Pingdom Bot

Purpose: Monitors website uptime and performance

User-Agent String:

Pingdom.com_bot_version_1.4_(http://www.pingdom.com/)

Behavior Characteristics:

Regular interval checks
Minimal resource usage
Multiple global locations
Legitimate monitoring

Should You Allow It? Yes if using Pingdom, otherwise optional

UptimeRobot

Purpose: Monitors website uptime

User-Agent String:

Mozilla/5.0+(compatible; UptimeRobot/2.0; http://www.uptimerobot.com/)

Behavior Characteristics:

5-minute check intervals
Lightweight requests
Only checks specified pages
Alerts on downtime

Should You Allow It? Yes if using service, block otherwise

GTmetrix

Purpose: Analyzes page speed performance

User-Agent String:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.101 Safari/537.36 GTmetrix

Behavior Characteristics:

On-demand crawling
Full page load testing
Performance metrics
User-initiated usually

Should You Allow It? Yes, useful for performance testing

StatusCake

Purpose: Uptime and performance monitoring

User-Agent String:

StatusCake

Behavior Characteristics:

Regular monitoring intervals
Global test locations
Page load testing
SSL monitoring

Should You Allow It? Yes if using service

Part 5: E-commerce and Price Monitoring Bots

These bots track prices and product availability.

Google Shopping Bot

Purpose: Indexes products for Google Shopping

User-Agent String:

Googlebot/2.1 (+http://www.google.com/bot.html) with commerce signals

Behavior Characteristics:

Focuses on product pages
Checks price updates
Monitors availability
Reads structured data

Should You Allow It? Yes for e-commerce sites

PriceSpider

Purpose: Where-to-buy solutions for brands

User-Agent String:

Mozilla/5.0 (compatible; PriceSpider/1.0)

Behavior Characteristics:

Monitors retailer sites
Tracks pricing
Checks inventory
Brand-authorized usually

Should You Allow It? Yes if selling tracked brands

Shopify Bot

Purpose: Powers Shopify’s various services

User-Agent String:

Various, includes Shopify

Behavior Characteristics:

Store verification
App integrations
Theme checking
Performance monitoring

Should You Allow It? Yes if using Shopify

Part 6: AI and Language Model Bots

New generation of bots training AI models and providing AI services.

GPTBot (OpenAI)

Purpose: Crawls content to train GPT models

User-Agent String:

GPTBot/1.0 (+https://openai.com/gptbot)

Behavior Characteristics:

Respects robots.txt
Can be blocked completely
Crawls for training data
Relatively new (2023+)

Controversial Aspects:

Uses content for AI training
No direct benefit to sites
Copyright concerns
Can be blocked via robots.txt

Should You Allow It? Controversial – many sites now block it

CCBot (Common Crawl)

Purpose: Builds public web dataset

User-Agent String:

CCBot/2.0 (https://commoncrawl.org/faq/)

Behavior Characteristics:

Massive scale crawling
Public dataset creation
Used by researchers
Can be resource-intensive

Who Uses the Data:

Academic researchers
AI companies
Data scientists
Various startups

Should You Allow It? Depends on your stance on public datasets

Anthropic-AI

Purpose: Crawls for Claude AI training

User-Agent String:

anthropic-ai
Claude-Web/1.0

Behavior Characteristics:

Similar to GPTBot
Training data collection
Respects robots.txt
New crawler

Should You Allow It? Your choice on AI training participation

Part 7: Malicious and Unwanted Bots

These bots should generally be blocked.

Scrapers and Content Thieves

Common Patterns:

Generic user agents
No identifying information
Aggressive crawling
Ignore robots.txt

Examples to Block:

Mozilla/5.0 (alone, no details)
Python-urllib
curl
wget
Java/1.8.0_151

How to Identify:

Unusual traffic patterns
High request rates
Downloading entire site
No referrer information

SEO Spam Bots

Purpose: Looking for vulnerabilities, comment forms, forums

Characteristics:

Random user agents
Rotating IPs
Target specific URLs
Post spam content

Common Targets:

WordPress login pages
Comment sections
Contact forms
Forum registrations

Aggressive Commercial Crawlers

Examples:

DataForSEO
Megaindex
BLEXBot
DomainCrawler

Why Block Them:

Excessive resource usage
No benefit to your site
Sell your data
Ignore crawl limits

Part 8: Managing Bot Traffic

Using robots.txt Effectively

Basic Structure:

# Allow search engines
User-agent: Googlebot
Allow: /

User-agent: Bingbot
Allow: /

# Block aggressive SEO bots
User-agent: AhrefsBot
Disallow: /

User-agent: MJ12bot
Crawl-delay: 10

# Block AI training bots
User-agent: GPTBot
Disallow: /

User-agent: CCBot
Disallow: /

Important Directives:

Disallow: Blocks access to paths
Allow: Explicitly allows access
Crawl-delay: Slows down crawling (not all bots respect)
Sitemap: Points to your sitemap

Server-Level Blocking

Using .htaccess (Apache):

# Block bad bots
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} ^.*(AhrefsBot|MJ12bot|SemrushBot).*$ [NC]
RewriteRule .* - [F,L]

Using nginx:

# Block bots in nginx
if ($http_user_agent ~* (AhrefsBot|MJ12bot|SemrushBot)) {
    return 403;
}

Monitoring Bot Traffic

Tools to Use:

Google Analytics (filter bot traffic)
Server logs analysis
Cloudflare Analytics
AWStats
GoAccess

What to Monitor:

Request frequency
Pages accessed
Resource usage
Response codes
Geographic origin

Red Flags:

Sudden traffic spikes
Sequential URL crawling
High 404 errors
Excessive bandwidth usage
Unusual time patterns

Part 9: Best Practices for Bot Management

Essential Bots to Allow

Never Block These:

Googlebot (search traffic)
Bingbot (second largest engine)
Facebook (social sharing)
Twitter (social sharing)
Your monitoring tools

Conditional Allows

Based on Your Business:

E-commerce: Shopping bots, price monitors
Publishers: News aggregators, feed readers
International: Regional search engines
B2B: LinkedIn bot
Technical: GitHub, documentation crawlers

Creating a Bot Strategy

Step 1: Audit Current Traffic

Analyze server logs
Identify all bot traffic
Calculate resource usage
Determine value per bot

Step 2: Define Policies

Essential bots (always allow)
Beneficial bots (usually allow)
Neutral bots (case-by-case)
Harmful bots (always block)

Step 3: Implement Controls

Update robots.txt
Configure server rules
Set up monitoring
Regular review schedule

Step 4: Monitor and Adjust

Weekly traffic reviews
Monthly bot audit
Quarterly policy update
Annual strategy review

Special Considerations

For Small Sites:

Focus on essential bots only
Block resource-intensive crawlers
Use crawl-delay liberally
Monitor server resources

For Large Sites:

Detailed bot policies
CDN-level controls
Rate limiting
Bot management services

For E-commerce:

Allow shopping bots
Monitor price scrapers
Protect product data
Balance visibility vs. protection

For Publishers:

Allow news aggregators
Manage archiving bots
Control content scraping
Protect premium content

Part 10: Future of Web Crawling

Emerging Trends

AI-Powered Crawling:

Smarter crawl patterns
Content understanding
Reduced server load
Better relevance detection

Privacy-Focused Changes:

Consent-based crawling
Data minimization
Regional restrictions
User agent transparency

Technical Evolution:

JavaScript rendering standard
API-first crawling
Real-time indexing protocols
Distributed crawling systems

Preparing for Changes

Website Owners Should:

Implement structured data
Use modern protocols (IndexNow)
Monitor emerging bots
Stay informed on standards
Plan for AI crawlers

Expected Developments:

More AI training bots
Stricter regulations
Better bot identification
Improved crawl efficiency
New authentication methods

Quick Reference Guide

Bots to Always Allow

Googlebot
Bingbot
Facebook/Instagram
Your monitoring services
Your CDN/security services

Bots to Usually Allow

DuckDuckGo
Twitter
LinkedIn
Pinterest
Yandex (if international)

Bots to Consider Blocking

AhrefsBot (competitor research)
SemrushBot (competitor research)
MJ12bot (aggressive)
GPTBot (AI training)
CCBot (dataset building)

Bots to Always Block

Suspicious user agents
Known scrapers
Spam bots
Vulnerability scanners
Excessive crawlers

Conclusion: Taking Control of Your Bot Traffic

Web crawlers are an essential part of the internet ecosystem, but not all bots deserve access to your content. The key is understanding which bots benefit your site and which ones just consume resources or potentially harm your business.

Your Action Plan:

This Week: Audit your current bot traffic using server logs
Next Week: Update your robots.txt with informed decisions
This Month: Implement monitoring for unusual bot activity
Ongoing: Review and adjust your bot policy quarterly

Remember: every bot accessing your site uses resources that cost money. Some bots pay back that cost through search visibility, social sharing, or valuable services. Others just take. Now you have the knowledge to tell the difference and act accordingly.

The landscape of web crawlers continues evolving, especially with AI training bots becoming more prevalent. Stay informed, monitor your traffic, and adjust your policies as needed. Your server resources, content, and business goals should drive your bot management strategy, not default settings or outdated assumptions.