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isbot πŸ€–/πŸ‘¨β€πŸ¦°

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


import { isbot } from "isbot";

// Nodejs HTTP

// ExpressJS

// Browser

// User Agent string
  "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

  "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36",
); // false

Using JSDeliver CDN you can import an iife script

See specific versions https://www.jsdelivr.com/package/npm/isbot or https://cdn.jsdelivr.net/npm/isbot

<script src="https://cdn.jsdelivr.net/npm/isbot@4"></script>
// isbot is global isbot(navigator.userAgent)

How isbot maintains accuracy

isbot's prized possession is the accurate identification of bots using a regular expression. It uses expansive and regularly updated lists of user agent strings to create a regular expression that matches bots and only bots.

This is done by using a lookbehind pattern which is not supported in all environments. A fallback is provided for environments that do not support lookbehind which is less accurate. The test suite includes a percentage of false positives and false negatives which is deemed acceptable for the fallback: 1% false positive and 75% bot coverage.

All named imports

import Type Description
isbot (string?): boolean Check if the user agent is a bot
isbotNaive (string?): boolean Check if the user agent is a bot using a naive pattern (less accurate)
getPattern (): RegExp The regular expression used to identify bots
list string[] List of all individual pattern parts
isbotMatch (string?): string | null The substring matched by the regular expression
isbotMatches (string?): string[] All substrings matched by the regular expression
isbotPattern (string?): string | null The regular expression used to identify bot substring in the user agent
isbotPatterns (string?): string[] All regular expressions used to identify bot substrings in the user agent
createIsbot (RegExp): (string?): boolean Create a custom isbot function
createIsbotFromList (string[]): (string?): boolean Create a custom isbot function from a list of string representation patterns

Example usages of helper functions

Create a custom isbot that does not consider Chrome Lighthouse user agent as bots.

import { createIsbotFromList, isbotMatches, list } from "isbot";

const ChromeLighthouseUserAgentStrings: string[] = [
  "mozilla/5.0 (macintosh; intel mac os x 10_15_7) applewebkit/537.36 (khtml, like gecko) chrome/94.0.4590.2 safari/537.36 chrome-lighthouse",
  "mozilla/5.0 (linux; android 7.0; moto g (4)) applewebkit/537.36 (khtml, like gecko) chrome/94.0.4590.2 mobile safari/537.36 chrome-lighthouse",
const patternsToRemove: Set<string> = new Set(
const isbot = createIsbotFromList(
  list.filter((record) => patternsToRemove.has(record) === false),

Create a custom isbot that considers another pattern as a bot, which is not included in the package originally.

import { createIsbotFromList, list } from "isbot";

const isbot = createIsbotFromList(list.concat("shmulik"));


  • 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.


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.

Data sources

We use external data sources on top of our own lists to keep up to date

Crawlers user agents

Non bot user agents

Missing something? Please open an issue

Major releases breaking changes (full changelog)

Remove named export "pattern" from the interface, instead use "getPattern" method

Remove isbot function default export in favour of a named export.

import { isbot } from "isbot";

Remove testing for node 6 and 8

Change return value for isbot: true instead of matched string

No functional change

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