Last updated
August 2, 2023

What is a Web Proxy? Their Purpose, Categories, and Use cases

Shyam Purkayastha

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The Internet is fundamentally built upon a client-server paradigm. A client computer requests a server computer, which returns a response. Behind the scenes, a set of intermediary networking devices are responsible for forwarding the requests and responses to the correct computers. A web proxy is a special kind of intermediary computer that acts on behalf of the client computer.

In this post, you will learn about web proxy servers, their purposes, various use cases, and their pros and cons.

What is a Web Proxy?

A web proxy listens to web traffic contained in TCP/IP packets and acts at the client's behest to request the web server. It routes all traffic between clients and servers. Depending upon the network configuration, it can either be a gateway or an intermediary server. The most common web proxy setup is in the form of an online proxy server configured on a web browser. In this case, all user-initiated web requests from the browser will be sent to the web proxy first instead of the website's hosting server.

A web proxy is usually deployed on a LAN network or hosted on the cloud. Assuming an office LAN setup connecting employees working on their computers, the web proxy is their gateway to access any website on the Internet. Cloud-hosted proxies usually offer additional security and privacy options. From an implementation perspective, web proxy servers can be software applications or dedicated server hardware.

What is the Purpose of a Web Proxy?

Web proxies evolved as online proxy gateways during the early days of the Internet. At that time, there was no way for computers connected over a LAN to send their web requests to the Internet directly or via a broadband router. Those were the days of dial-up networking. A typical small office setup would consist of a computer designated for Internet access via the dial-up modem and connected to the telephone network as well as the local LAN network. This computer had the web proxy configured, and designated as the web proxy server. Other computers in the LAN would be configured to route their internet traffic through this web proxy server.

WinProxy was one of the earliest web proxy software available on Windows 95/98. Under the Linux family of OSs, Squid was a popular choice for software-based free web proxy servers.

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Additional Capabilities of Web Proxy Servers

From their humble beginnings as an online proxy to transparently route traffic between LAN to dial-up networks, web proxies have taken on additional functions over the years. They have also evolved from a pure software-based web proxy to a more hardware and cloud-native offering. Some of the critical functional capabilities added to the various web proxy product over the years include:

  1. Firewall: Since a web proxy routes traffic to and from the Internet, firewall capabilities are a natural extension to traffic handling. By adding a firewall layer with associated rules for allowing or blocking ports and IP address ranges, a proxy server can perform the role of a firewall in addition to its primary function. 
  2. Caching: Web proxies gather a log of data about the type of content served to the users. This data is a treasure trove of information that can be harnessed intelligently to find out which content is going viral or accessed frequently. Accordingly, proxy servers have attached storage to cache frequently accessed content. This approach makes web browsing faster for users and saves a ton of Internet bandwidth.
  3. Content Filtering: Since web proxies work on the application layer, they can be used as an effective means to filter web content based on pre-defined rules. This feature, along with firewall capabilities, gives a lot of flexibility to companies to enforce policies related to Internet access and web browsing to their staff. 
  4. Load Balancing: Proxy servers working in a cluster can provide load balancing capabilities to distribute the user traffic. This scenario applies to large enterprises with thousands of employees.
  5. Security and Anonimyzation: Many web proxies serve as a gateway to provide better encryption and anonymization of information related to the user accessing the Internet.  That’s why web proxies offer a certain amount of inherent protection from cyber attacks.    

Difference between Forward Proxy and Reverse Proxy

A web proxy is also known as a forward proxy. Thus, it forwards the user's requests over the Internet and is also responsible for orchestrating the responses back to the user. 

There is another kind of proxy, the reverse proxy. This type of proxy plays the opposite role of a forward proxy, wherein it routes the requests to specific server applications running at the backend. The reverse proxy is deployed at the server end and hides the application server-specific endpoints and networks. 

Difference between Web Proxy and VPN Servers

At a high level, a web proxy and VPN may seem similar since both act as intermediaries. However, VPN servers use a tunneling mechanism that encapsulates and encrypts the IP packets within another packet routed over a secured path. Therefore, VPN provides a much greater degree of security compared to a web proxy.

Related: How to detect if an IP address is using a VPN

VPNs can be slow in routing traffic due to the additional overheads of tunneling and encryption. To circumvent this problem, they are usually deployed using a Multi Protocol Label Switching (MPLS) network that leverages label switching for hop-by-hop packet routing, which is faster than IP-based routing. This network architecture is suitable for large enterprises, with many remote workers logging into their office network through VPN.

How does a Web Proxy Work?

The default behavior of a web proxy is that of a packer forwarder. In this case, it replaces the source IP address of the packet originating from a user's client computer with the proxy server's IP address. This packet is then forwarded to the server where the request was originally destined. Upon receiving a response from the server, the proxy server replaces the destination IP address of the response packet with the IP address of the user's client computer to route it to that computer over LAN.

This scenario is a simple Layer 3 operation of the web proxy server. It intercepts all the packets originating from LAN. It maintains an internal memory to store the local private IP address of all the client computers to perform the IP address replacement operation for every outgoing and incoming packet.

What is Proxy IP Address?

The proxy IP address is a public IP address. It is attached to the web proxy's hosting server, also known as the proxy server. This IP address routes traffic from the local network to the Internet and vice versa. It hides the client computer's IP address. Therefore, the server receiving the packets from the client computer can see only the web proxy's IP address.

Related: How to detect if an IP address is using a proxy

Proxies with Advanced Features  

Proxy servers with more advanced features, such as content filtering, caching, and firewall capabilities, can intercept and decipher the application and transport layer headers in a packet to perform additional operations.  

For example, a proxy server configured to filter our requests to a website, will intercept every outgoing packet and check if the application layer contains an HTTP request payload containing this website in the URI field. Similarly, a proxy server with firewall capabilities checks for the allowed ports in the transport layer headers.    

Types of Web Proxy

Web proxies were initially intended to provide an additional layer of supervision to simplify access to the Internet. However, as stated earlier, their scope and functionality have expanded since their inception. As such, there are no set standards for defining the types of web proxies.

However, based on the underlying implementation and deployment scenarios over a network, there are a few ways to differentiate them.

Software vs. Hardware 

Most web proxies are in the form of a software suite. They can be installed on general-purpose computer hardware and configured to serve their intended purposes. These are cheap and less complex to set up. Hardware-based proxy servers are deployed on dedicated hardware, offering a larger scale to handle massive traffic. In addition, they are equipped with additional storage to enable content caching and monitoring.

Transparent vs. Non-Transparent

A transparent proxy acts as a mere observer of web traffic. These proxies intercept all the web traffic but do not alter the packets. Their sole purpose is to monitor and log user activity over a network. On the other hand, non-transparent proxies change the packets to act as a gateway that makes requests on behalf of the users.

Anonymous vs. Non-Anonymous

An anonymous proxy is configured to hide the details of user requests. In some cases, these proxies are chained together to create multiple layers of packet wrapping to conceal the origination of the web traffic. In this way, they make the packets completely untraceable. Non-anonymous proxies are the usual proxy servers that do not hide their IP address.  

Residential vs. Mobile

A residential web proxy is deployed to serve fixed IP addresses per the users' physical location. These are deployed by ISPs to serve the users of a particular location. Mobile proxies are deployed to rotate IP addresses belonging to mobile data networks from various locations worldwide.

Standalone vs. Networked

A standalone proxy is deployed as a single proxy server that exposes one or limited IP addresses to the Internet. A networked proxy is a cluster of many proxy servers which expose a wide range of IP addresses to the Internet for each request sent out.

Application vs. Protocol

Application proxies are used to orchestrate the web traffic mainly encapsulated in HTTP requests and responses. As a result, all users' web browsing activities fall under the purview of these proxies. However, some particular kinds of proxies are designated for intercepting specific protocol operations. These operations are also part of web-based applications. However, these operations do not fall under typical web browsing activities.

For example, a Session Initiation Protocol (SIP) proxy intercepts a Voice over Internet Protocol (VoIP) call initiated via the SIP protocol to forward a call initiation request to the destination number's SIP proxy. Similarly, a Domain Name Service (DNS) proxy acts as a local domain lookup service and performs DNS resolution on behalf of the users.

Use Cases of Web Proxy

From small to large offices, consumers to businesses, web proxy finds many use cases.

Moderation of Internet Access

All organizations have a set of IT policies, including internet access regulations. Enforcing these regulations via a web proxy is ideal for monitoring employee activity. In addition, with a web proxy capable of firewall and content filtering, organizations can set up rules and guidelines for employees to abide by the IT policy.

Enhancement of Internet Access

Web proxies with content caching capabilities provide an enhanced browsing experience. By caching web pages within the web proxy, organizations can avoid the round trip delay to the hosting server of that content on the Internet, thereby aiding in significant speed improvements. 

Data Scraping

Web scraping is one of the most widely used methods for extracting information from the Internet. However, due to its repeated nature, many websites block scraping requests from the same IP address. By leveraging a proxy network supporting a large IP address pool, companies can deploy web scraping applications behind these proxy networks to effectively carry out scraping operations by spreading the requests across many IP addresses.

Testing of Location Related Services

Many web applications are programmed to show location-specific information. For example, a web application accessed by a user from a specific country may see an advert targeted for that country. How do the application developers test such features dependent on access from a particular country? Using a web proxy configured with IP addresses belonging to the address pool of that country, developers can test whether the adverts are reaching the targetted audience.

Enhanced Security over the Internet

Web proxies can encapsulate the web traffic in an encrypted packet stream, thereby maintaining privacy for users. Combined with a VPN, they can enable enhanced security by routing user traffic through a highly secured VPN tunnel that safeguards personally identifiable information and sensitive data exchanged over the Internet.

Guarding Against Cyber Attacks

Web proxies send the requests on behalf of the client computer, thereby hiding the networking configuration of the client computers. This approach provides a natural barrier against incoming cyber-attacks on client computers. Furthermore, web proxies operating in a load balancer mode also offer a considerable barrier against Denial of Service (DoS) attacks.  

Circumventing Internet Restrictions

Web proxy offers a convenient way to circumvent regulations on accessing certain services over the Internet from certain territories of the world. Internet users can leverage a web proxy server to confiscate their IP address and location, thereby accessing services that are otherwise barred from their actual location. Many free proxy servers deployed over the cloud offer this facility.

Drawbacks of using Web Proxy

Web proxies have a lot of genuine applications in an enterprise network. However, from an individual user’s perspective, there are always questions about using them.

Are Web Proxies Safe?

The safety of proxy services is purely dependent on the additional security and privacy features provided by the proxy server.

Many Internet users rely on free web proxy servers advertised over the Internet. While these servers may serve their intended purpose, there is a risk of a security breach if sensitive information related to payments and credit card details are transferred. These proxies usually offer little security. Moreover, they might have been set up by hackers with fraudulent intentions to steal user information by logging their online activities.

Users who take the services from a premium proxy service will most likely be safe from such fraud.

Are Web Proxies Legal?

The legality of proxy servers is a debatable topic. It is subject to the territorial laws of the country where the proxy server is hosted or the country of origin from where the user is accessing the proxy server. Unfortunately, there is no objective way to answer this question. However, for the explanation, here are two situations covering both sides of the law.

Using proxies to hide the actual location and IP address is considered legal as long as the user is not committing a cybercrime. In such cases, the law enforcement requirements mandate the proxy servers to maintain the logs of user IP addresses through which the actual user can be traced.

If a user tries to gain access to a website via some free proxy service, which is otherwise barred by their country, this activity is considered illegal.


What is a Web Proxy?

A web proxy is an intermediary server deployed on a private network to route the web traffic from within the network to the outside world, that is, the Internet. Web proxy comes with different features and various form factors. Any client computer accessing the Internet from a private network will send the request to the web proxy. The web proxy, in turn, will route that request to the Internet. While receiving the response from the Internet in the reverse path, the web proxy routes the response back to the originating client computer. In this way, the web proxy acts as a server as well as a client. It is a server for the client computer and a client to the destination server on the Internet.

Why would a Hacker use a Proxy Server?

Hackers use proxy servers to hide their actual location. When sending a request via a proxy server, the hacker's exact IP address is replaced by the proxy server's IP address, thereby concealing their real identity. This approach helps them undertake clandestine operations without being caught. However, using a free web proxy over the Internet does not guarantee the privacy of their identity, as these servers primarily maintain a log of IP addresses from where requests are coming. To completely secure their activity over the Internet, hackers leverage a chain of anonymous proxy servers that adds multiple layers of encryption to the packets, making them untraceable.

Which is Better, Proxy or VPN?

Proxy and VPN have different purposes. A proxy is an intermediary server that intercepts all the web traffic through a network. By default, it monitors and routes traffic to and from the Internet, acting on behalf of the client computers. A VPN also acts as an intermediary, but it offers better security and routing. A VPN comprises many servers through which the traffic is tunneled via a highly secure and encrypted packet format and routed using label switching for faster transmission. In comparison, a Proxy may comprise one or more servers, but it cannot offer the highly secured transmission provided by a VPN. However, Proxy and VPN can be combined as a set of networked computers to provide the best of both worlds.

Shyam Purkayastha
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