# yasserg/crawler4j

Open Source Web Crawler for Java

Repository: https://github.com/yasserg/crawler4j
Canonical: https://ross.abutalabs.com/products/crawler4j
Language: Java
License: Apache-2.0
License Family: permissive
Last push: 2021-11-04T08:31:46+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5359, "days_push": 1763, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4618, forks 1897 (observed 2026-08-28T04:08:55.135007+00:00)

## What it is
crawler4j is an open-source web crawler library for Java that provides a simple interface for building multi-threaded web crawlers in minutes. Users extend a WebCrawler class to decide which URLs to visit and how to process fetched pages.

## Use cases
- crawl a website and extract all pages
- build a multi-threaded web crawler in Java
- scrape HTML content and extract links from pages
- collect data from websites for indexing or analysis
- filter which URLs the crawler should visit
- download and parse web pages at scale

## When to choose
- you need a simple, ready-to-use crawler on the JVM
- you want multi-threaded crawling with minimal setup
- you need URL filtering and HTML parsing out of the box

## When to avoid
- you need a JavaScript-rendered (headless browser) crawler
- you need a distributed or highly scalable crawling system
- you're not working on the JVM platform
- you need actively maintained software with recent releases

## Facets
- artifact type: library
- maturity: maintenance
- function: web-scraping, http-client, parser
- domain: crawlers, web-development, developer-tools
- platform: jvm, cross-platform
- tags: web-crawler, java, multi-threaded, html-parsing

## Member repositories
- yasserg/crawler4j (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:55.135007+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:19:40.144081+00:00, confidence not recorded.
  - readme: https://github.com/yasserg/crawler4j (fetched 2026-08-28T04:08:55.135007+00:00, sha 1df6c1609c45)
- Data as of 2026-08-30T08:39:29.467469+00:00.