isbot 🤖/👨‍🦰

Detect bots/crawlers/spiders using the user agent string.

Usage

import isbot from 'isbot'

// Nodejs HTTP
isbot(request.getHeader('User-Agent'))

// ExpressJS
isbot(req.get('user-agent'))

// Browser
isbot(navigator.userAgent)

// User Agent string
isbot('Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5376e Safari/8536.25 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)') // true
isbot('Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36') // false

Additional functionality

Extend: Add user agent patterns

Add rules to user agent match RegExp: Array of strings

isbot('Mozilla/5.0') // false
isbot.extend([
    'istat',
    '^mozilla/\\d\\.\\d$'
])
isbot('Mozilla/5.0') // true

Exclude: Remove matches of known crawlers

Remove rules to user agent match RegExp (see existing rules in src/list.json file)

isbot('Chrome-Lighthouse') // true
isbot.exclude(['chrome-lighthouse']) // pattern is case insensitive
isbot('Chrome-Lighthouse') // false

Find: Verbose result

Return the respective match for bot user agent rule

isbot.find('Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 DejaClick/2.9.7.2') // 'DejaClick'

Matches: Get patterns

Return all patterns that match the user agent string

isbot.matches('Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 SearchRobot/1.0') // ['bot', 'search']

Clear:

Remove all matching patterns so this user agent string will pass

const ua = 'Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 SearchRobot/1.0';
isbot(ua) // true
isbot.clear(ua)
isbot(ua) // false

Spawn: Create new instances

Create new instances of isbot. Instance is spawned using spawner's list as base

const one = isbot.spawn()
const two = isbot.spawn()

two.exclude(['chrome-lighthouse'])
one('Chrome-Lighthouse') // true
two('Chrome-Lighthouse') // false

Create isbot using custom list (instead of the maintained list)

const lean = isbot.spawn([ 'bot' ])
lean('Googlebot') // true
lean('Chrome-Lighthouse') // false

Definitions

Bot. Autonomous program imitating or replacing some aspect of a human behaviour, performing repetitive tasks much faster than human users could.
Good bot. Automated programs who visit websites in order to collect useful information. Web crawlers, site scrapers, stress testers, preview builders and other programs are welcomed on most websites because they serve purposes of mutual benefits.
Bad bot. Programs which are designed to perform malicious actions, ultimately hurting businesses. Testing credential databases, DDoS attacks, spam bots.

Clarifications

What does "isbot" do?

This package aims to identify "Good bots". Those who voluntarily identify themselves by setting a unique, preferably descriptive, user agent, usually by setting a dedicated request header.

What doesn't "isbot" do?

It does not try to recognise malicious bots or programs disguising themselves as real users.

Why would I want to identify good bots?

Recognising good bots such as web crawlers is useful for multiple purposes. Although it is not recommended to serve different content to web crawlers like Googlebot, you can still elect to

Flag pageviews to consider with business analysis.
Prefer to serve cached content and relieve service load.
Omit third party solutions' code (tags, pixels) and reduce costs.

It is not recommended to whitelist requests for any reason based on user agent header only. Instead other methods of identification can be added such as reverse dns lookup.