What Is a Reverse Proxy?
Defining reverse proxies: what are they and how do they work?
A reverse proxy sits between clients and servers, acting as an intermediary. One of its main purposes is load balancing, which distributes incoming traffic across multiple backend servers to ensure optimal performance.
It can handle client requests for static content, such as images or HTML files, by serving them directly from its cache. It can also handle requests for dynamic content by forwarding them to the appropriate backend server, which generates the content in real-time.
By receiving incoming requests and forwarding them to backend servers on their behalf, the reverse proxy can filter and block unwanted or malicious traffic while allowing legitimate requests through. It can also monitor and modify traffic on the fly, and act as an intermediary for authentication schemes like OAuth 2.0 — allowing users to log in to multiple services using a single set of credentials.
Overall, reverse proxies play a crucial role in improving performance, scalability, and security for web applications.
Reverse proxies sit in front of servers, while forward proxies usually sit in front of clients. To compare both sides of proxy architecture, read our guide to forward proxies and the basics of public and private IP addresses. For broader networking context, see what a DNS server is.
Common use cases for reverse proxy servers
Reverse proxy servers play a crucial role in modern web infrastructure — from enhanced security and load balancing to caching and SSO. Here are the patterns you'll meet most often in production.
Load balancing
Distribute incoming network traffic across multiple servers to ensure optimal resource utilization, prevent server overload, and improve application performance. Particularly valuable in high-traffic websites and applications.
SSL termination
Handle SSL/TLS encryption and decryption on behalf of backend servers, offloading the resource-intensive task of managing secure connections. Optimizes server performance and simplifies certificate management.
Web acceleration and caching
Cache static content such as images, stylesheets, and scripts to reduce backend load and accelerate content delivery. Improves overall website performance and responsiveness.
Security and access control
Acts as a protective barrier between the public internet and internal servers. Implements WAFs and access controls to defend against common web attacks and unauthorized access to sensitive resources.
Content compression
Compress content before delivering it to clients, reducing bandwidth usage and speeding up page loading times for users — particularly beneficial for users with slower internet connections.
Application firewall
Add an extra layer of security by inspecting and filtering incoming traffic for potential threats and vulnerabilities, protecting against common web application attacks.
Single sign-on (SSO)
Facilitate single sign-on solutions, allowing users to access multiple applications with a single set of credentials. Simplifies user authentication and improves user experience.
API gateway
Serve as API gateways, managing and securing communication between clients and backend APIs. Enforce authentication, authorization, and traffic management for API requests.
Server-side GTM
Route analytics and marketing data through your own server before it reaches third-party services. Improves data privacy, control, and website performance — a common pattern with server-side Google Tag Manager.
Benefits and drawbacks of a reverse proxy server
Whether you're aiming for improved performance or navigating operational complexity, a balanced view is key. Here's where reverse proxies help — and where they ask something of you in return.
Improved website performance
Reverse proxies optimize performance by efficiently routing traffic. This reduces backend server loads, preventing bottlenecks and ensuring a smooth user experience.
Enhanced security
They serve as gateways, providing an additional layer of security. They filter and block malicious traffic, safeguarding against cyber threats and protecting private data centers from direct access.
Efficient load balancing
Distribute incoming traffic across multiple servers. Increases scalability, ensures high availability, and optimizes resource utilization, preventing server overload.
Scalability
Facilitates scalability and resilience by distributing requests among backend servers and managing traffic efficiently.
Increased complexity
Implementation and maintenance introduce complexity to the infrastructure. Proper configuration and ongoing management are necessary for optimal functionality.
Single point of failure
Relying on a single reverse proxy creates a potential point of failure. Downtime can disrupt web services — redundancy is essential.
Latency
In certain scenarios, reverse proxy servers may introduce latency due to additional processing. This may slightly delay communication between clients and web servers.
Resource overhead
Running a reverse proxy consumes resources, particularly in high-traffic environments. Sufficient resource allocation is required for smooth and efficient operation.
Reverse proxy vs. forward proxy and load balancers
Reverse proxies overlap with other pieces of infrastructure but occupy a distinct role. Here's how they line up against the two they get confused with most.
Should you put a reverse proxy in front of your app?
Reverse proxies play a crucial role in enhancing security, performance, and scalability for web applications. By acting as an intermediary between clients and servers, they efficiently distribute incoming requests, cache content, and protect against malicious attacks.
While the benefits — improved load balancing, simplified network architecture, hardened security — are real, it's important to consider the drawbacks: increased complexity and a potential single point of failure. Ultimately, the decision to implement a reverse proxy should be based on the specific needs and requirements of the application.
Key takeaways
What to remember about reverse proxies
- Reverse proxies sit between clients and your origin servers
- They improve performance through caching, compression, and load balancing
- They add a security layer — WAFs, SSL termination, access control
- They simplify single sign-on and API gateway patterns