WebReaper is a declarative high performance web scraper, crawler and parser in C#. Designed as simple, extensible and scalable web scraping solution. Easily crawl any web site and parse the data, save structed result to a file, DB, or pretty much to anywhere you want.

It provides a simple yet extensible API to make web scraping a breeze.

• Install
• Requirements
• Features
• Usage examples
• API overview
  • Parsing Single Page Applications
  • Persist the progress locally
  • Authorization
  • How to disable headless mode
  • How to clean scraped data from the previous web scrapping run
  • How to clean visited links from the previous web scrapping run
  • How to clean job queue from the previous web scraping run
  • Distributed web scraping with Serverless approach
  • Extensibility
    • Adding a new sink to persist your data
  • Intrefaces
  • Main entities
• Repository structure

dotnet add package WebReaper 

.NET 8

• ⚡ High crawling speed due to parallelism and asynchrony
• 🗒 Declarative and easy to use
• 💾 Saving data to any data storages such as JSON or CSV file, MongoDB, CosmosDB, Redis, etc.
• 🌎 Scalable: run your web scraper on ony cloud VMs, serverless functions, on-prem servers, etc.
• 🐙 Crawling and parsing Single Page Applications with Puppeteer
• 🖥 Proxy support
• 🌀 Extensible: replace out-of-the-box implementations with your own

• Data mining
• Gathering data for machine learning
• Online price change monitoring and price comparison
• News aggregation
• Product review scraping (to watch the competition)
• Tracking online presence and reputation

Parsing single page applications is super simple, just use the GetWithBrowser and/or FollowWithBrowser method. In this case Puppeteer will be used to load the pages.

usingWebReaper.Builders;varengine=awaitnewScraperEngineBuilder().GetWithBrowser("https://www.alexpavlov.dev/blog").FollowWithBrowser(".text-gray-900.transition").Parse(new(){new("title",".text-3xl.font-bold"),new("text",".max-w-max.prose.prose-dark")}).WriteToJsonFile("output.json").PageCrawlLimit(10).WithParallelismDegree(30).LogToConsole().BuildAsync();awaitengine.RunAsync();

Additionally, you can run any JavaScript on dynamic pages as they are loaded with headless browser. In order to do that you need to add some page actions such as .ScrollToEnd():

usingWebReaper.Core.Builders;varengine=awaitnewScraperEngineBuilder().GetWithBrowser("https://www.reddit.com/r/dotnet/", actions =>actions.ScrollToEnd().Build()).Follow("a.SQnoC3ObvgnGjWt90zD9Z._2INHSNB8V5eaWp4P0rY_mE").Parse(new(){new("title","._eYtD2XCVieq6emjKBH3m"),new("text","._3xX726aBn29LDbsDtzr_6E._1Ap4F5maDtT1E1YuCiaO0r.D3IL3FD0RFy_mkKLPwL4")}).WriteToJsonFile("output.json").LogToConsole().BuildAsync() await engine.RunAsync();Console.ReadLine();

It can be helpful if the required content is loaded only after some user interactions such as clicks, scrolls, etc.

If you want to persist the visited links and job queue locally, so that you can start crawling where you left off you can use ScheduleWithTextFile and TrackVisitedLinksInFile methods:

varengine=awaitnewScraperEngineBuilder().WithLogger(logger).Get("https://rutracker.org/forum/index.php?c=33").Follow("#cf-33 .forumlink>a").Follow(".forumlink>a").Paginate("a.torTopic",".pg").Parse(new(){new("name","#topic-title"),new("category","td.nav.t-breadcrumb-top.w100.pad_2>a:nth-child(3)"),new("subcategory","td.nav.t-breadcrumb-top.w100.pad_2>a:nth-child(5)"),new("torrentSize","div.attach_link.guest>ul>li:nth-child(2)"),new("torrentLink",".magnet-link","href"),new("coverImageUrl",".postImg","src")}).WriteToJsonFile("result.json").IgnoreUrls(blackList).ScheduleWithTextFile("jobs.txt","progress.txt").TrackVisitedLinksInFile("links.txt").BuildAsync();

If you need to pass authorization before parsing the web site, you can call SetCookies method on Scraper that has to fill CookieContainer with all cookies required for authorization. You are responsible for performing the login operation with your credentials, the Scraper only uses the cookies that you provide.

varengine=awaitnewScraperEngineBuilder().WithLogger(logger).Get("https://rutracker.org/forum/index.php?c=33").SetCookies(cookies =>{cookies.Add(newCookie("AuthToken","123");}) ...

If you scrape pages with a browser using GetWithBrowser and FollowWithBrowser methods, the default mode is headless meaning that you won't see the browser during scraping. However, seeing the browser during scraping for debugging or troubleshooting may be useful. To disable headless mode you the .HeadlessMode(false) method call.

varengine=awaitnewScraperEngineBuilder().GetWithBrowser("https://www.reddit.com/r/dotnet/", actions =>actions.ScrollToEnd().Build()).HeadlessMode(false) ...

You may want to clean the data recived during the previous scraping to start you web scraping from scratch. In this case use dataCleanupOnStart when adding a new sink:

varengine=awaitnewScraperEngineBuilder().Get("https://www.reddit.com/r/dotnet/").WriteToJsonFile("output.json",dataCleanupOnStart:true)

This dataCleanupOnStart parameter is present for all sinks, e.g. MongoDbSink, RedisSink, CosmosSink, etc.

To clean up the list of visited links just pass true for dataCleanupOnStart parameter:

varengine=awaitnewScraperEngineBuilder().Get("https://www.reddit.com/r/dotnet/").TrackVisitedLinksInFile("visited.txt",dataCleanupOnStart:true)

Job queue is a queue of tasks schedules for web scraper. To clean up the job queue pass the dataCleanupOnStart parameter set to true.

varengine=awaitnewScraperEngineBuilder().Get("https://www.reddit.com/r/dotnet/").WithTextFileScheduler("jobs.txt","currentJob.txt",dataCleanupOnStart:true)

In the Examples folder you can find the project called WebReaper.AzureFuncs. It demonstrates the use of WebReaper with Azure Functions. It consists of two serverless functions:

First of all, this function uses ScraperConfigBuilder to build the scraper configuration e. g.:

Secondly, this function writes the first web scraping job with startUrl to the Azure Service Bus queue:

This Azure function is triggered by messages sent to the Azure Service Bus queue. Messages represent web scraping job.

Firstly, this function builds the spider that is going to execute the job from the queue.

Secondly, it executes the job by loading the page, parsing content, saving to the database, etc.

Finally, it iterates through these new jobs and sends them the the Job queue.

Out of the box there are 4 sinks you can send your parsed data to: ConsoleSink, CsvFileSink, JsonFileSink, CosmosSink ( Azure Cosmos database).

You can easily add your own by implementing the IScraperSink interface:

publicinterfaceIScraperSink{publicTaskEmitAsync(ParsedDatadata);}

Here is an example of the Console sink:

publicclassConsoleSink:IScraperSink{publicTaskEmitAsync(ParsedDataparsedItam){Console.WriteLine($"{parsedItam.Data.ToString()}");returnTask.CompletedTask;}}

Adding your sink to the Scraper is simple, just call AddSink method on the Scraper:

varengine=awaitnewScraperEngineBuilder().AddSink(newConsoleSink());.Get("https://rutracker.org/forum/index.php?c=33").Follow("#cf-33 .forumlink>a").Follow(".forumlink>a").Paginate("a.torTopic",".pg").Parse(new(){new("name","#topic-title"),}).BuildAsync();

For other ways to extend your functionality see the next section.

• Job - a record that represents a job for the spider
• LinkPathSelector - represents a selector for links to be crawled

See the LICENSE file for license rights and limitations (GNU GPLv3).