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ARC Proxies

Glossary · Networking

Reverse proxy

A reverse proxy is a server that sits in front of one or more web servers and receives requests as if it were the site, then forwards them inward; RFC 9110 calls it a gateway, "an intermediary that acts as an origin server for the outbound connection", and it is chosen by the site operator, not by the visitor.

Reviewed 30 Oct 2026

See alsoForward proxyX-Forwarded-ForRate limitingIP reputation

What a reverse proxy does for a site

  • TLS termination. It holds the certificate and decrypts traffic, so backend servers do not have to.
  • Load balancing. It spreads requests across several application servers and stops sending to unhealthy ones.
  • Caching and compression. Content delivery networks are, at their core, distributed reverse proxies.
  • Filtering. Request-rate limits, bot rules and web application firewall checks usually run here, before a request reaches the application.

How it differs from the proxy you configure

A forward proxy works for the client: you point your software at it and it reaches any site. A reverse proxy works for one site: visitors never configure it and usually cannot tell it is there. A request through ARC typically passes both — the forward gateway you chose, then the site's own reverse proxy.

Why it matters for data collection

The reverse proxy is the first thing your request meets, so it is where your exit address is logged, where rate limiting is applied and where a 429 or a challenge page is usually generated. It also tells the backend who the client was, often by adding X-Forwarded-For or the standard Forwarded header (RFC 7239) — and the address it records there is your proxy's exit.

A 429 from the edge is the operator's capacity statement, whichever server produced it. Back off as described in handling 429 rate limits.

FAQ

Questions

Something not covered? Write to contact@arcproxies.io.

Is a CDN a reverse proxy?

Functionally, yes. A content delivery network places reverse proxies close to visitors, answers from cache where it can and forwards the rest to the site's origin servers.

Is a load balancer the same as a reverse proxy?

An HTTP load balancer is a kind of reverse proxy whose main job is spreading requests across servers. Many reverse proxies also balance load, so the terms are often used for the same box.

Can a visitor tell that a site uses a reverse proxy?

Sometimes, from response headers such as Via or Server, or from the address the hostname resolves to. Often not: a well-configured reverse proxy answers exactly as the site would.

Do I need a reverse proxy to use ARC?

No. ARC's gateway is a forward proxy that your client connects to. Reverse proxies are on the site's side and you do not configure them.

Sources & review

Last reviewed by the ARC Proxies team. Prices are read from the live catalog at build time.

  1. [1]IETF: RFC 9110: HTTP Semantics
  2. [2]IETF: RFC 7239: Forwarded HTTP Extension

In practice

Where reverse proxy matters

GuideHandling 429 rate limitsWhat HTTP 429 means, how to read Retry-After, and how to retry politely with exponential backoff, jitter and per-host concurrency limits. With code.Use caseProxies for web scraping and data collectionA second provider that just works — Scrapy, requests, Crawlee or Playwright, self-serve, no sales call, bandwidth that never expires.Use caseProxies for QA, app and localisation testingSee your own site the way a user in Tokyo, São Paulo or Munich sees it — currency, language, consent banner, CDN edge and all — before they report it.IntegrationcurlSend curl through an authenticated proxy with -x and -U, check the exit IP, test sticky sessions and countries, use socks5h, and read 407 failures.