What is Web Scraping?
Basically The scraping Script is used where The API's Are not provided by the Web application.

Web scraping is a technique to fetch a large amount of data from a web application and display it or save it in a file for further use.

Often, companies need to extract volumes of data from a particular site to process and analyze. Web scraping with Ruby on Rails is an easy way to do that.

It is used to crawling and fetch  required data from a static website or a JS rendered website.

When talking about web scraping using Ruby, here are a few terms to get familiar with:

Few terms to get familiar with:
Nokogiri:
A gem for web scraping Ruby, Nokogiri, uses CSS selectors or XPath for web scraping.
Capybara:
Allows JS-based interaction with the websites.
Kimurai:
It is a framework for web scraping with Ruby.
Combination of Nokogiri + Capybara.
Allows scraping data for JS rendered websites and even static HTTP requests.
There are few tools available for web scrapings such as Nokogiri, Capybara and Kimurai. But, Kimurai is the most powerful framework to scrape data.

Kimurai
A web scraping framework in ruby works out of the box with Headless Chromium/Firefox, PhantomJS, or simple HTTP requests and allows us to scrape and interact with JavaScript rendered websites. t also aligns with any Ruby web scraping library for better functionalities.

Features :

Ruby web scraping for Javascript websites.
Supports Headless Chrome, Headless Firefox, PhantomJS or Simple HTTP requests(mechanize) engines.
Capybara methods used to fetch data.
Rich library for built-in helpers to make scraping easy.
Parallel Scrapping – Process web pages concurrently.
Pipelines: To organize and store data in one place for processing all spiders.
You can also scrape data from JS rendered websites, i.e. infinite scrollable websites and even static websites. Amazing right  !!! 

Read Also: Web scraping using Mechanize in Ruby on Rails

Static Websites:
You can use this framework in 2 ways:

Underconstruction