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Gocrawl is a polite, slim and concurrent web crawler library written in Go. It is designed to be simple and easy to use, while still providing a high degree of flexibility and control over the crawling process.

One of the key features of Gocrawl is its politeness, which means that it obeys the website's robots.txt file and respects the crawl-delay specified in the file. It also takes into account the website's last modified date, if any, to avoid recrawling the same page. This helps to reduce the load on the website and prevent any potential legal issues. Gocrawl is also highly concurrent, which allows it to efficiently crawl large numbers of pages in parallel. This helps to speed up the crawling process and reduce the time required to complete the task.

The library also offers a high degree of flexibility in customizing the crawling process. It allows you to specify custom callbacks and handlers for handling different types of pages, such as error pages, redirects, and so on. This allows you to handle and process the pages as per your requirement. Additionally, Gocrawl provides various functionalities such as support for cookies, user-agent, auto-detection of links, and auto-detection of sitemaps.

Ferret is a web scraping system. It aims to simplify data extraction from the web for UI testing, machine learning, analytics and more. ferret allows users to focus on the data. It abstracts away the technical details and complexity of underlying technologies using its own declarative language. It is extremely portable, extensible, and fast.


  • Declarative language
  • Support of both static and dynamic web pages
  • Embeddable
  • Extensible

Ferret is always implemented in Python through pyfer

Example Use

// Only enqueue the root and paths beginning with an "a"
var rxOk = regexp.MustCompile(`http://duckduckgo\.com(/a.*)?$`)

// Create the Extender implementation, based on the gocrawl-provided DefaultExtender,
// because we don't want/need to override all methods.
type ExampleExtender struct {
    gocrawl.DefaultExtender // Will use the default implementation of all but Visit and Filter

// Override Visit for our need.
func (x *ExampleExtender) Visit(ctx *gocrawl.URLContext, res *http.Response, doc *goquery.Document) (interface{}, bool) {
    // Use the goquery document or res.Body to manipulate the data
    // ...

    // Return nil and true - let gocrawl find the links
    return nil, true

// Override Filter for our need.
func (x *ExampleExtender) Filter(ctx *gocrawl.URLContext, isVisited bool) bool {
    return !isVisited && rxOk.MatchString(ctx.NormalizedURL().String())

func ExampleCrawl() {
    // Set custom options
    opts := gocrawl.NewOptions(new(ExampleExtender))

    // should always set your robot name so that it looks for the most
    // specific rules possible in robots.txt.
    opts.RobotUserAgent = "Example"
    // and reflect that in the user-agent string used to make requests,
    // ideally with a link so site owners can contact you if there's an issue
    opts.UserAgent = "Mozilla/5.0 (compatible; Example/1.0; +"

    opts.CrawlDelay = 1 * time.Second
    opts.LogFlags = gocrawl.LogAll

    // Play nice with ddgo when running the test!
    opts.MaxVisits = 2

    // Create crawler and start at root of duckduckgo
    c := gocrawl.NewCrawlerWithOptions(opts)

    // Remove "x" before Output: to activate the example (will run on go test)

    // xOutput: voluntarily fail to see log output
// Example scraper for Google in Ferret:
LET google = DOCUMENT("", {
    driver: "cdp",
    userAgent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.87 Safari/537.36"

HOVER(google, 'input[name="q"]')
INPUT(google, 'input[name="q"]', @criteria, 30)
CLICK(google, 'input[name="btnK"]')

WAITFOR EVENT "navigation" IN google

WAIT_ELEMENT(google, "#res")

LET results = ELEMENTS(google, X("//*[text() = 'Search Results']/following-sibling::*/*"))

FOR el IN results
    RETURN {
        title: INNER_TEXT(el, 'h3')?,
        description: INNER_TEXT(el, X("//em/parent::*")),
        url: ELEMENT(el, 'a')?.attributes.href

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