When a user opens a web app, their request rarely travels straight to a single backend server. It may pass through load balancers, gateways, firewalls, caches, content delivery networks, and identity systems before the application responds.

A reverse proxy is one of the most common components in that path. It sits in front of backend services and helps route, protect, and optimize traffic. For developers and infrastructure teams, understanding reverse proxies is essential for designing reliable and secure web applications.

For enterprise and B2B SaaS teams modernizing customer-facing infrastructure, reverse proxies often sit alongside identity systems, gateways, and custom domains. This article explains what is a reverse proxy, how it works, how it differs from a forward proxy, and how it fits into secure application and identity architecture with Auth0 Custom Domains.

• What is a reverse proxy: A server that receives client requests and forwards them to backend services
• Reverse proxies can support routing, load balancing, caching, Transport Layer Security (TLS) termination, and traffic filtering
• A forward proxy represents clients; a reverse proxy represents servers
• Reverse proxies can reduce direct exposure of internal services but do not replace authentication or authorization
• Auth0 Custom Domains help teams create trusted, branded authentication experiences as part of secure deployment architecture
• For enterprise platform teams, reverse proxies and identity systems both contribute to resilient, scalable customer-facing infrastructure

A reverse proxy is an intermediary server that sits between users and backend applications. It receives incoming requests from clients and forwards them to the appropriate backend server or service.

From the user’s perspective, the reverse proxy may look like the application. The user does not need to know which backend service handled the request, how many servers are running, or where the application infrastructure lives.

That abstraction gives infrastructure teams more control over routing, availability, performance, and security.

A reverse proxy receives a request, evaluates where it should go, forwards it to a backend service, receives the response, and returns that response to the client.

Function	What it does
Routing	Sends requests to the right service or application
Load balancing	Distributes traffic across multiple backend servers
TLS termination	Handles encrypted HTTPS connections at the edge
Caching	Serves repeated responses more efficiently
Compression	Reduces response size when appropriate
Filtering	Blocks or limits suspicious or malformed traffic
Header management	Adds or removes headers as requests move downstream

In microservice environments, reverse proxies can simplify how external clients reach many internal services.

A forward proxy and reverse proxy are both intermediaries, but they sit on different sides of the connection.

Comparison point	Forward proxy	Reverse proxy
Represents	Clients	Servers
Typical use	Controls outbound access from users or networks	Controls inbound access to backend applications
Common examples	Corporate web proxy, privacy proxy, content filter	Load balancer, Application Programming Interface gateway, edge proxy
Client awareness	The client may be configured to use it	The client often interacts with it as the application endpoint
Security role	Protects or governs users’ outbound requests	Protects or governs application inbound traffic

A simple way to remember it: forward proxies sit in front of clients, while reverse proxies sit in front of servers.

Teams use reverse proxies for many infrastructure patterns.

Use case	Why teams use a reverse proxy
Load balancing	Distributes requests across multiple application servers
Microservice routing	Sends requests to the right internal service
TLS termination	Centralizes certificate handling at the edge
Backend protection	Reduces direct exposure of internal systems
Blue-green deployments	Routes traffic between application versions
API routing	Directs API calls to the right backend service
Caching	Improves performance for repeated responses

Reverse proxies are especially useful when applications scale beyond a single server. They give teams a central layer for traffic handling without exposing every backend system directly to the internet.

Reverse proxies can reduce direct exposure by keeping backend services behind an intermediary. Instead of opening every internal service to external traffic, teams can expose only the proxy and route approved requests from there.

This can help with:

• Reducing the public attack surface
• Keeping internal hostnames and ports private
• Applying consistent TLS settings
• Filtering malformed or excessive requests
• Centralizing routing logic

However, a reverse proxy is not a complete security model. Backend services still need authentication, authorization, input validation, logging, monitoring, and least-privilege access controls.

Reverse proxies often sit near identity systems in the request path, but they should not be confused with identity providers.

A reverse proxy can route traffic to login pages, enforce some edge policies, or pass headers to downstream applications. An identity provider authenticates users, issues tokens, and supports secure login flows. Applications and APIs still need to validate tokens and enforce authorization decisions.

This distinction matters. If a team assumes the proxy alone proves identity, downstream services may trust requests they should verify. Secure architecture uses the proxy as one layer, not the only layer.

Auth0 Custom Domains allow teams to use their own domain name on authentication pages. In secure deployment architecture, Custom Domains help make authentication flows feel consistent and trustworthy within the customer experience.

For enterprise, retail, and B2B SaaS teams managing many customer touchpoints, consistent authentication experiences can support trust while reducing identity complexity for developers.

Explore Auth0 Custom Domains to align customer authentication with your brand and application architecture.

What is a reverse proxy and how does it protect internal servers from the internet?

A reverse proxy sits in front of backend servers and forwards approved requests to them. It can reduce direct exposure of internal services, but backend systems still need strong authentication, authorization, and network controls.

What is the difference between a forward proxy and a reverse proxy setup?

A forward proxy represents clients making outbound requests. A reverse proxy represents servers receiving inbound requests and forwarding them to backend services.

How do network teams use reverse proxies to hide sensitive user database endpoints?

Network teams should avoid exposing database endpoints directly to the internet. Reverse proxies can route application traffic, but databases should be protected with private networking, strict access controls, authentication, authorization, and monitoring.

Does a reverse proxy replace authentication?

No. A reverse proxy can support traffic handling and some security controls, but it does not replace an identity provider, token validation, or application-level authorization.

Using a service like Auth0 can simplify the implementation of both authentication and authorization, allowing developers to concentrate on their core application logic. Explore our Intro to IAM series for additional topics related to identity and access management.

Learn more

These materials are intended for general informational purposes only. You are responsible for obtaining security, privacy, compliance, or business advice from your own professional advisors and should not rely solely on the information provided herein.

• Building a Reverse Proxy in .NET Core
• Custom Domains
• Configure Features to Use Custom Domains