Reverse Proxy vs Load Balancer vs API Gateway
How modern web apps route, protect, and manage traffic between clients and backend services.
Three components at your front door
Story: imagine your app as a busy airport. Passengers arrive at one front door, but behind the scenes many teams keep things moving-security, air‑traffic control, and gate agents.
Reverse proxy is the security checkpoint: it hides the private side of the airport and inspects what comes in.
Load balancer is air‑traffic control: it decides which runway (server instance) each plane uses so nothing collides.
API gateway is the gate agent: it checks tickets, enforces rules, and sends people to the exact plane (service) they need.
They often work together. Knowing who does what stops you from cramming all jobs into one overworked component.
Reverse proxy
- Hides backend servers from the internet
- Terminates HTTPS, offloading TLS from apps
- Adds caching, compression, and request filtering
- Presents a single entry point for many services
Load balancer
- Spreads traffic across a pool of instances
- Uses algorithms like round robin or least connections
- Runs health checks and removes unhealthy backends
- Enables horizontal scaling and high availability
API gateway
- API-aware front door for many services
- Handles auth, rate limiting, and quotas
- Routes by path or version to the right service
- Transforms requests/responses for different clients
Reverse proxy: security and edge optimizations
One server in front—many real servers behind. One clean public endpoint that protects and optimizes.
What it feels like
Users think they're talking to one server; the proxy quietly passes requests to real app servers behind it.
Privacy shield
Hides internal IPs and hostnames so attackers never see your actual app nodes.
TLS offload at the edge
Terminates HTTPS once, then plain HTTP to your app—crypto work stays off your code.
Speed tricks
Caching, compression, and request filtering before traffic reaches your application.
Load Balancer: traffic distribution and resilience
One entry point, many servers. Traffic is spread so no single instance is overwhelmed.
Mental model
Traffic cop at a highway on-ramp—waves each car into the lane that keeps everything flowing.
Spread the load
Sends each request to one of many instances so no single server melts under traffic spikes.
Smart routing
Round robin, least connections, and IP hash choose the best next instance automatically.
Health checks
Probes backends and stops sending traffic to any instance that starts failing.
API gateway: API-aware front door for microservices
One front door for all your APIs—auth, routing, and policies in one place instead of duplicated everywhere.
API concierge
Clients talk to one URL; the gateway fans requests out to dozens of microservices.
Security guard
Validates tokens, API keys, and roles before any request touches your services.
Abuse protection
Rate limits and quotas stop a single noisy client from overwhelming your APIs.
Router & translator
Sends /v1/payments vs /v2/payments to the right service; can reshape headers or payloads.
When to use which
Small app or monolith? Start with a reverse proxy (optionally with simple load balancing) to handle TLS, caching, and basic protection.
Growing microservices? Add an API gateway so teams get a single, well‑managed entry point for every API consumer.
Big, high‑traffic platform? Expect to use all three: an external load balancer in front of a fleet of reverse proxies or API gateways, which then route to internal services.
Rule of thumb: the more services and clients you have, the more value you get from a dedicated API gateway layer.
Rule of thumb: the more services and clients you have, the more value from a dedicated API gateway.
Reverse proxy (optionally with simple load balancing) for TLS, caching, and basic protection.
Add an API gateway for a single, well-managed entry point for every API consumer.
Use all three: load balancer in front of reverse proxies or API gateways, then route to internal services.
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