What are Reverse Proxies and How do They Differ from Forward Proxies

Proxy servers can be categorized by many factors: their purpose, how they are used, their level of anonymity, and more. One of the key distinctions is based on where the intermediate server sits in the network path. From this perspective, we differentiate between forward and reverse types.

Understanding how these two models differ is critical for companies that rely on network technologies in commercial products and infrastructure. The choice of solution directly affects web service performance, data protection, and the resilience of the overall architecture to external threats. This article explains what a reverse proxy is, which tasks it solves, and how it differs from a forward proxy.

How reverse proxies work

A reverse proxy is a component of network infrastructure whose primary role is to accept incoming requests, process them according to predefined logic, and safely route them to the target servers. It offloads the infrastructure and adds an extra control and protection layer at the network perimeter.

A typical reverse proxy workflow looks like this:

1. A user initiates a request, for example by opening a web page.
2. The request is sent to the reverse proxy.
3. The intermediate server forwards the request to the origin server that hosts the required data.
4. The origin server returns a response to the reverse proxy, which then relays it to the user.

In this model, the reverse proxy sits between the client (for example, a browser or an application) and the origin server, and hides the real IP address of the latter.

Use cases of reverse proxies

Considering the location of reverse proxies, they can be effectively used in several scenarios:

• Distributing incoming requests across multiple servers in a cluster to balance the load, for example with NGINX or HAProxy.
• Caching static content (images, style sheets, scripts) to reduce response time, as in solutions such as Varnish Cache.
• Improving web application performance through data compression, reducing the number of HTTP requests, and performing pre-processing of responses — an approach used in NGINX and Varnish, where compression and caching speed up page loading and reduce load on the origin server.
• Protecting the origin from DDoS attacks by filtering suspicious traffic, analyzing request frequency, and automatically blocking malicious activity.
• Masking the IP address of the origin server to add a further protection layer, as in services like Akamai and Fastly, which hide the internal network infrastructure.
• Redirecting part of the traffic to healthy backup servers to maintain fault tolerance during failures or maintenance.

From these traditional functions, it's clear that a reverse proxy plays a critical role in ensuring the stable operation of the end server and in safeguarding it from various threats.

What are forward proxies and what are they used for

Reverse and forward proxies serve different roles based on their location and functions. To understand the difference, let's examine how forward proxies operate:

1. The user sets up a proxy on their device or within their software, and, for example, opens a page in the browser.
2. When accessing a web resource, the request is sent not from the user’s real IP address but from the address of the intermediate server.
3. The final server receives the request from the proxy rather than directly from the user.
4. The intermediate server returns the response to the client.

In this case, the solution sits between the user and the web resource, relaying requests and responses between them.

It's important to recognize that forward proxies vary in their levels of anonymity, which classifies them into transparent and anonymous proxies. Transparent proxies do not conceal the user’s original IP address nor the fact that a proxy is being used, and they are typically employed for routing requests.

Anonymous proxies, on the other hand, completely mask the user’s IP address and obscure the use of a proxy. They are particularly useful for several purposes:

• Testing regional availability and localization by emulating traffic from target regions to verify UI behavior, payment systems, and local services.
• Using them together with antidetect browsers to isolate environments and distribute IP addresses when managing multiple accounts on social networks, marketplaces, and online platforms.
• Automating actions in online services with distributed requests that simulate natural user activity for data collection, monitoring, and process management without overloading systems or triggering platform safeguards.
• Protecting user traffic from interception and other malicious activities.

Forward proxies can be hosted in various locations such as data centers, ISP servers, or mobile devices, each providing different levels of accessibility and security.

Differences between reverse proxies and forward proxies

The table below summarizes the key differences between reverse and forward solutions:

The difference between these two types lies not only in how they process requests but also in their purpose. Forward proxies focus on outgoing traffic: they mask user IP addresses, support IP rotation, and provide controlled access to resources. Reverse solutions, on the other hand, manage and filter incoming traffic, protecting and optimizing the operation of origin servers.

FAQ

Can forward and reverse proxies be used together?

Yes. Large infrastructures often combine both: reverse proxies protect servers and balance incoming traffic, while forward proxies handle outgoing data in a controlled and distributed way.

Which is more expensive — forward or reverse proxies?

Reverse proxies are usually more expensive because they require server resources, infrastructure configuration, and ongoing maintenance by DevOps or system engineers. Forward proxies are often cheaper, as they are provided as ready-made services and do not require deployment on the client side.

Can proxies be combined with WAF (Web Application Firewall) systems?

Yes. Reverse proxies are frequently integrated with WAF solutions to block malicious requests and SQL injections at the perimeter before they reach the application. Forward proxies can also be used together with WAF or IDS/IPS systems to analyze outgoing traffic, control user requests, and prevent data leaks from a corporate network.