Integration · Browsers & operating systems

How to use a proxy in Firefox

Firefox has its own proxy settings, independent of the operating system: Settings → General → Proxy settings → Configure proxy opens the Connection Settings dialog. Choose Manual proxy configuration, enter the gateway as the HTTP Proxy, tick Also use this proxy for HTTPS, and Firefox asks for the username and password on the first request. Its SOCKS v5 fields have no place for credentials, so a password-protected SOCKS5 gateway needs an extension.

Reviewed 30 Oct 2026

your proxy, as a URL1 line

http://USERNAME_pool-arcfast_country-de:PASSWORD@proxy.arcproxies.io:8000

The short answer

Enter the gateway in HTTP Proxy and tick Also use this proxy for HTTPS; Firefox prompts for the username and password.
Firefox's Connection Settings dialog cannot send SOCKS5 credentials; the request for this feature (bug 122752) is still open.
An extension can: Firefox's proxy API accepts a username and password for SOCKS5, which is what FoxyProxy uses.
Proxy DNS when using SOCKS v5 is on by default in current Firefox, so hostnames are resolved by the proxy, not your local resolver.

Setup

Set up Firefox with a proxy, step by step

01
Open Connection Settings
In Firefox 159, open Settings, stay on General and scroll to Proxy settings, then click Configure proxy. Older releases label the same section Network Settings with a Settings… button. Typing proxy into the settings search box finds it in every version.
02
Enter the gateway as an HTTP proxy
Select Manual proxy configuration and fill in the fields below. Ticking Also use this proxy for HTTPS copies the HTTP proxy to the HTTPS fields; HTTPS sites then go through a CONNECT tunnel with TLS end to end. Leave the SOCKS fields empty.
Connection Settings4 lines
```
(•) Manual proxy configurationHTTP Proxy:  proxy.arcproxies.io        Port: 8000[x] Also use this proxy for HTTPSNo proxy for: localhost, 127.0.0.1
```
03
Sign in on the first request
Firefox shows an authentication prompt for the proxy. Enter the ARC username and password; a sticky username keeps the exit IP the same while you browse. If you let Firefox save the password, ticking Do not prompt for authentication if password is saved in the same dialog stops the prompt on later starts.
Authentication Required2 lines
```
User Name: USERNAME_pool-arcfast_country-de_session-k3f9a1x2_sesstime-10Password:  PASSWORD
```

Or set it in a profile's user.js

For a dedicated testing profile, the same settings can live in user.js in the profile folder (find it under about:profiles). Firefox applies the file at every start. The password is still entered at the prompt, never in this file.

user.js7 lines

user_pref("network.proxy.type", 1);                    // manual configurationuser_pref("network.proxy.http", "proxy.arcproxies.io");user_pref("network.proxy.http_port", 8000);user_pref("network.proxy.share_proxy_settings", true);  // also use for HTTPSuser_pref("network.proxy.ssl", "proxy.arcproxies.io");user_pref("network.proxy.ssl_port", 8000);user_pref("network.proxy.no_proxies_on", "localhost, 127.0.0.1");

05
Check the exit IP
Load an IP echo page. It should show an address in the country from the username. Testing a proxy's location adds checks for time zone and language.
address bar1 line
```
https://api.ipify.org?format=json
```

HTTP or SOCKS v5 in Firefox?

Behaviour	HTTP Proxy (+ HTTPS)	SOCKS v5 in Connection Settings	SOCKS5 via extension
Username and password	Prompt, can be saved	Not supported	Stored in the extension
DNS resolution	By the gateway (hostname sent in CONNECT)	By the proxy when Proxy DNS is ticked (default)	By the proxy when Proxy DNS is on
Works with ARC rotating plans	Yes	No (no IP allowlisting)	Yes

For everyday use the HTTP route is enough. SOCKS5 through FoxyProxy is useful when you want per-tab or per-container proxies with stored credentials.

Proxy DNS and DNS over HTTPS

Proxy DNS when using SOCKS v5 (network.proxy.socks5_remote_dns) sends hostnames to the SOCKS proxy instead of resolving them locally, which prevents a DNS leak to your own resolver. Current Firefox ticks it by default; it only applies when a SOCKS proxy is in use.

With the HTTP proxy the option does not apply: HTTPS requests carry the hostname in the CONNECT line and plain-HTTP requests carry the full URL, so the gateway resolves the name in both cases.

Separate identities with containers

Firefox containers keep cookies apart inside one window. FoxyProxy can assign a proxy per container on Firefox, so one container browses through a German session and another through a French one, each with its own sticky session username. That suits ad verification and website testing where you compare markets side by side.

The problem

Common pitfalls

Only the HTTP field filled

Without Also use this proxy for HTTPS (or an HTTPS Proxy entry), HTTPS sites, which is almost all of them, go out directly. Tick the box and recheck the exit IP.

SOCKS v5 with the gateway

Entering the gateway under SOCKS Host fails on rotating plans: Firefox sends no SOCKS username or password, and the gateway does not allowlist IPs. Use HTTP, or SOCKS5 through an extension.

An extension overriding the dialog

If a proxy extension is in control, Settings shows that it controls how Firefox connects and the manual fields have no effect. Disable the extension or configure the proxy there.

Your main profile

A proxy in the main profile also carries your logged-in sessions and sync traffic through the gateway. Create a separate profile in about:profiles for proxied work.

FAQ

Questions

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

Where are the proxy settings in Firefox?

Settings → General → Proxy settings → Configure proxy in Firefox 159 (Network Settings → Settings… in older releases). The Connection Settings dialog has the manual HTTP, HTTPS and SOCKS fields. Searching proxy in Settings finds it in any version.

How do I use a proxy with a username and password in Firefox?

Enter the host and port as an HTTP proxy, tick Also use this proxy for HTTPS, and type the username and password into the prompt Firefox shows on the first request. Firefox can save them in its password manager.

Does Firefox support SOCKS5 authentication?

Not in the Connection Settings dialog; that feature request is still open in Mozilla's bug tracker. Firefox's extension API does accept a SOCKS5 username and password, so extensions such as FoxyProxy can use an authenticated SOCKS5 proxy.

What does Proxy DNS when using SOCKS v5 do?

It makes Firefox send hostnames to the SOCKS proxy for resolution instead of using your local DNS, so the lookups do not reveal the sites you visit to your network. It is on by default and has no effect with an HTTP proxy.

Sources & review

Last reviewed 30 October 2026 by the ARC Proxies team. Prices are read from the live catalog at build time.

[1]Mozilla: Connection settings in Firefox
[2]Mozilla (Firefox source): connection.ftl: Connection Settings labels (release)
[3]Mozilla Bugzilla: Bug 122752: SOCKS: Username/Password Authentication (V5)
[4]MDN Web Docs: proxy.ProxyInfo: username, password and proxyDNS for SOCKS

What people build with it

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.Use caseProxies for ad verification and ad testingConfirm your creatives render where you paid for them, in the geo you bought, and that they are not sitting next to something that damages the brand.Use caseProxies for social media and multi-accountingOne stable exit per profile, held as long as the session needs, so the accounts you are entitled to run stay separate in an anti-detect browser.IntegrationFoxyProxyAdd an authenticated proxy to FoxyProxy in Chrome or Firefox: stored username and password, Proxy by Patterns per site, SOCKS5 and per-port credentials.GlossaryDNS leakA DNS leak is when a client sends its traffic through a proxy or VPN but resolves hostnames through its own local resolver, so the lookups leave from the original network — exposing which sites you visit to that resolver and, for location-dependent services, possibly connecting you to a server picked for the wrong place.GlossarySticky sessionA sticky session is a setting on a rotating proxy that keeps the same exit IP address for a chosen period, usually by attaching a session identifier to the connection, so a multi-step task appears to come from one address from start to finish.GuideHow to test a proxy's locationCheck a proxy's exit IP and geolocation with curl, why IP geolocation databases disagree, and how to verify what the target site actually sees.Use caseProxies for ad verification and ad testingConfirm your creatives render where you paid for them, in the geo you bought, and that they are not sitting next to something that damages the brand.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.

Integrations

Other browsers & operating systems

ChromeSet a proxy in Google Chrome: system settings, the --proxy-server flag and the sign-in prompt, plus why SOCKS5 with a password needs another route.macOSSet an authenticated proxy on a Mac: System Settings → Network → Details → Proxies, the networksetup commands, bypass lists and which apps follow it.WindowsSet a proxy in Windows 11 and 10: Network & internet → Proxy, the credential prompt, netsh winhttp for services, and PowerShell and curl.exe tests.FoxyProxyAdd an authenticated proxy to FoxyProxy in Chrome or Firefox: stored username and password, Proxy by Patterns per site, SOCKS5 and per-port credentials.

Get started

Get credentials and paste them in.

Sign up, buy a gigabyte, generate a username in the dashboard. Code WELCOME15 takes 15% off your first purchase; bandwidth never expires.

Create your account Questions first? contact@arcproxies.io