Web scraping for machine learning

An introduction to web scraping as a method of data acquisition for ML applications


Hi, we're Apify, a cloud platform that helps you build reliable web scrapers fast and automate anything you can do manually in a web browser. This article on web scraping for machine learning was inspired by our work on collecting data for AI and ML applications.

What is web scraping?

At its simplest, web scraping is the automated extraction of data from websites. This process is akin to web crawling, which is about finding or discovering web links. The difference is that web scraping is focused on extracting that data.

Initially, web scraping was a manual, cumbersome process, but with technological advances being what they are, it has become an automated, sophisticated practice. Web scrapers can navigate websites, understand their structure, and extract specific information based on predefined criteria.

Web scraping 101: learn the basics

Why is web scraping used in machine learning?

“In most cases, you can’t build high-quality predictive models with just internal data.” 

- Asif Syed, Vice President of Data Strategy, Hartford Steam Boiler

The ability to harvest and process data from a myriad of web sources is what makes web scraping indispensable for machine learning. Web scraping isn't just about accessing the data but transforming it from the unstructured format of web pages into structured datasets that can be efficiently used in machine learning algorithms.

You can't teach a machine to make predictions or carry out tasks based on data unless you have an awful lot of data to train it. From social media analytics to competitive market research, web scraping enables the gathering of diverse datasets to teach machines, such as today's so-called 'AI models', and provide them with a rich and nuanced understanding of the world.

Comparing data collection methods for machine learning

There are multiple ways to collect data for machine learning — these range from traditional surveys and manually curated databases to cutting-edge techniques that utilize IoT devices. So, why choose web scraping over other methods of data acquisition?

  • Surveys: They can provide highly specific data but often suffer from biases and limited scope.
  • Databases: These offer structured information, yet they may lack the real-time aspect essential for certain machine learning applications.
  • IoT devices: These bring in a wave of real-time, sensor-based data, but they're constrained by the type and quantity of data they can collect. It's worth noting that implementing MQTT authentication enhances the security and efficiency of data transmission and allows these devices to communicate more reliably.
  • Web scraping: In contrast, web scraping provides access to an almost infinite amount of data available online, from text and images to metadata and more. Unlike surveys or databases, web scraping taps into real-time data, which is crucial for models requiring up-to-date information. Moreover, the diversity of data that can be scraped from the web is unparalleled, which allows for a more comprehensive training of machine learning models.

Learn about building functional AI models for web scraping

Quality and quantity of data in ML

“You can have all of the fancy tools, but if your data quality is not good, you're nowhere.” 

- Veda Bawo, Director of Data Governance, Raymond James

The adage "quality over quantity" holds a significant place in many fields, but in the world of machine learning, it's not a matter of choosing one over the other. The success of ML models is deeply rooted in the quality and quantity of data they're trained on.

Quality of data refers to its accuracy, completeness, and relevance. High-quality data is free from errors, inconsistencies, and redundancies, making it indispensable for dependable analysis and sound decision-making. On the other hand, the quantity of data pertains to its volume. A larger dataset provides more information, leading to more reliable models and improved outcomes. However, an abundance of low-quality data can be detrimental, potentially leading to inaccurate predictions and suboptimal decision-making.

When it comes to quantity, web scraping allows for the collection of vast amounts of data from various online sources. However, the web is full of low-quality data, so simply extracting raw data isn't enough. It needs to be cleaned and processed before it can be used for machine learning. More about that later.

Another crucial aspect of data for machine learning is variety. Web scraping provides access to diverse data to enhance a model's ability to understand and interpret varied inputs.

Cloud-based real-time data acquisition

In the context of machine learning, the ability to collect and process data in real time is increasingly becoming a necessity rather than a luxury. This is where cloud-based data acquisition plays a vital role, as - in opposition to Edge-based data acquisition - it offers scalability and flexibility, which are critical for handling the voluminous and dynamic nature of web data.

Cloud computing, with its vast storage and computational capabilities, allows for the handling of massive datasets that web scraping generates. It provides the infrastructure needed to collect, store, and process data from varied sources in real-time. This real-time aspect is especially important in applications like market analysis, social media monitoring, and predictive modeling, where the timeliness of data can be the difference between relevance and obsolescence.

Learn about the differences between Edge AI and Cloud AI

Web scraping challenges and techniques for machine learning

The efficacy of web scraping in machine learning hinges on several key techniques. These not only ensure the extraction of relevant data but also its transformation into a format that machine learning algorithms can effectively utilize.

Handling dynamic websites

A major challenge in web scraping is dealing with dynamic websites that continually update their content. These sites often use technologies like JavaScript, AJAX, and infinite scrolling, making data extraction more complex. To effectively scrape such sites, one must employ advanced techniques and tools, seeking the expertise of pioneers in the field, such as companies specializing in software development services. Advanced techniques and tools are required. These include methods for executing JavaScript, handling AJAX requests, and navigating through dynamically loaded content. Mastering these techniques enables the scraping of real-time data from these complex websites, a critical requirement for many machine-learning applications.

Blocking and blacklisting

Many websites have measures in place to detect and block scraping bots to prevent unauthorized data extraction. These measures include blacklisting IP addresses, deploying CAPTCHAs, and analyzing browser fingerprints. To counteract blocking, web scrapers employ techniques like rotating proxies, mimicking real browser behaviors, and making use of CAPTCHA-solving services.

Heavy server load

Web scrapers can inadvertently overload servers with too many requests, leading to performance issues or even server crashes. To prevent this, it’s essential to implement intelligent crawl delays, randomize scraping times, and distribute the load across multiple proxies. This approach ensures a polite and responsible scraping process that minimizes the impact on website servers.

What do you do with the scraped data?

Data preprocessing

We said earlier that scraping raw data isn't enough. The next critical step involves cleaning and transforming the raw data into a structured format suitable for machine learning models. This stage includes removing duplicates and inconsistencies, handling missing values, and normalizing data to ensure that it's free from noise and ready for analysis. Preprocessing ensures that the data fed into machine learning models is of high quality, which is essential for accurate results.

Feature selection

Once the data is preprocessed, the next step is to identify and extract the most relevant features from the dataset. This involves analyzing the data to determine which attributes are most significant for the problem at hand. By focusing on the most relevant features, the efficiency and performance of machine learning models are significantly enhanced. This step - known also as feature engineering - can also help in reducing the complexity of the model to make it faster and more efficient.

Integrating web data with ML applications

Once you have your data, you need a way to integrate it with other tools for machine learning. Here are some of the most renowned libraries and databases for ML:


This open-source framework is revolutionizing the way developers integrate large language models (LLMs) with external components in ML applications. It simplifies the interaction with LLMs, facilitating data communication and the generation of vector embeddings. LangChain's ability to connect with diverse model providers and data stores makes it the ML developer's library of choice for building on top of large language models.

Learn more about LangChain

Hugging Face

Renowned for its datasets library, Hugging Face is one of the most popular frameworks in the machine learning community. It provides a platform for easily accessing, sharing, and processing datasets for a variety of tasks, including audio, computer vision, and NLP, making it a crucial tool for ML data readiness.

Learn more about Hugging Face


This tool's ecosystem is vast, integrating with technologies like vector databases and various model providers. It serves as a flexible and dynamic solution for developers looking to incorporate complex functionalities in their ML projects.

Learn more about Haystack


LlamaIndex represents a significant advancement in the field of machine learning, particularly in its ability to augment large language models with custom data. This tool addresses a key challenge in ML: the integration of LLMs with private or proprietary data. It offers an approachable platform for even those with limited ML expertise, allowing for the effective use of private data in generating personalized insights.

With functionalities like retrieval-augmented generation (RAG), LlamaIndex enhances the capabilities of LLMs, making them more precise and informed in their responses. Its indexing and querying stages, coupled with various types of indexes, such as List, Vector Store, Tree, and Keyword indexes, provide a stable infrastructure for precise data retrieval and use in ML applications.

Learn how to integrate Apify with LlamaIndex to feed vector databases and LLMs with data crawled from the web

Pinecone and other vector databases

ML models need numerical data, known as embeddings in machine learning, so any data you've collected has to be stored in and retrieved from a vector database.


This vector database stands out for its high performance and scalability, which are crucial for ML applications. It's developer-friendly and allows for the creation and management of indexes with simple API calls. Pinecone excels in efficiently retrieving insights and offers capabilities like metadata filtering and namespace partitioning, making it a reliable tool for ML projects.

Learn more about Pinecone


As an AI-native open-source embedding database, Chroma provides a comprehensive suite of tools for working with embeddings. It features rich search functionalities and integrates with other ML tools, including LangChain and LlamaIndex.

For more vector databases, check out 6 open-source Pinecone alternatives

Your first web scraping challenge

If you haven't done web scraping before, we've made it easy (and free) for you to get started. Apify has created a tool ideal for data acquisition for machine learning: Website Content Crawler.

Learn how to use Website Content Crawler

This tool was specifically designed to extract data for feeding, fine-tuning, or training machine learning models such as LLMs. You can retrieve the results using the API to formats such as JSON or CSV, which can be fed directly to your LLM or vector database. You can also integrate the data with LangChain using the Apify LangChain integration.

Theo Vasilis
Theo Vasilis
Writer, Python dabbler, and crafter of web scraping tutorials. Loves to inform, inspire, and illuminate. Interested in human and machine learning alike.

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