Browsers, Antidetect Tools and Phones

A buyer types a proxy into the Windows settings page, opens Chrome and sees a German IP. A curl command in the terminal on the same machine still reports the office address. The proxy works. It was set in a place that only some programs read.

Where the proxy setting lives

A proxy can be set at four levels, and each one covers less of the machine than the one before. Setting it at the wrong level is a common reason traffic leaves through the wrong IP.

On Windows the system setting sits under Settings, Network & internet, Proxy. On macOS it sits under System Settings, Network, the active connection, Details, Proxies. Chrome, Edge and Safari read these panels. Many command-line tools do not. They look for the HTTP_PROXY and HTTPS_PROXY environment variables, or for a flag such as curl -x.

A system proxy is a preference, not a tunnel. Nothing forces an app to honor it. A device that must push every packet through another network needs a VPN.

Firefox, Chrome and extensions

Firefox keeps its own proxy settings under Settings, General, Network Settings. The panel can follow the system, take a manual HTTP or SOCKS proxy, or load a PAC file. That makes Firefox the simplest way to run one proxied browser beside a normal one.

Two details matter. The "Proxy DNS when using SOCKS v5" box from Chapter 3 should stay ticked. The panel also has no fields for a SOCKS username and password, so SOCKS5 in Firefox works best with IP allowlisting. HTTP proxies prompt for credentials on first use.

Chrome has no proxy panel of its own. Its settings page opens the operating system's panel instead. A proxy for Chrome alone takes one of two routes:

• A launch flag. Starting Chrome with --proxy-server and a separate --user-data-dir gives a second, proxied instance.
• An extension. Proxy-switcher extensions use Chrome's proxy API to set a proxy for one Chrome profile. Pick a publisher with a track record, because the extension can see every URL.

# macOS: a second Chrome with its own profile and proxy
"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" \
  --user-data-dir="$HOME/chrome-proxy-de" \
  --proxy-server="gate.example-proxy.com:7000"

# Linux: the same idea
google-chrome --user-data-dir="$HOME/chrome-proxy-de" \
  --proxy-server="gate.example-proxy.com:7000"

The flag cannot carry a username and password. Chrome asks for them in a prompt, or the provider allowlists the machine's IP. Chrome also does not support SOCKS5 with a username and password, so use the provider's HTTP port or allowlisting.

Antidetect browsers: one profile, one proxy

An agency manages 12 client ad accounts from one laptop. In a normal browser those accounts share cookies, a fingerprint and an IP. In an antidetect browser each account gets a profile with its own storage, its own fingerprint and its own proxy.

The proxy field is only part of what these tools add:

• Isolated storage. Cookies, local storage and cache never cross between profiles.
• A stable fingerprint. Each profile reports the same canvas, WebGL, font, screen and user-agent values every time it opens.
• Location that follows the IP. Many tools can set timezone, language and geolocation from the proxy's exit address.
• Team and automation features. Profiles can be shared with colleagues or driven through an API.

The full antidetect browser list covers the rest. Pair each profile with one steady address: a static ISP proxy or a long sticky residential session. An account that logs in from a new city every ten minutes looks wrong, however good the fingerprint is. ProxyLook's companion book, The Multi-Account Handbook, covers account work in depth.

Phones: Wi-Fi settings and cloud phones

Android and iOS both accept a proxy per Wi-Fi network in the system settings, and only an HTTP proxy.

Menu names vary by phone maker and system version. Two gaps remain on both systems: SOCKS5, and apps that ignore the Wi-Fi proxy. A proxy client app that registers as a local VPN closes both, because it captures all traffic on the device.

Cloud phones solve a different problem. TikTok, Instagram and similar platforms are built app-first, and an app can read far more device detail than a web page can. A cloud phone is an Android device hosted in a data center and controlled remotely. Each one has its own device identity and its own proxy setting.

• GeeLark offers Android cloud phones plus browser profiles, with metered running time.
• DuoPlus offers Android cloud phones only, opened from a browser tab. It charges a per-device fee plus metered running time, and comes from the team behind AdsPower.
• Multilogin offers Android cloud phones alongside its browser profiles.

Mobile or residential proxies suit cloud phones best. A phone app that arrives from a server-farm IP tells two different stories at once. Metered running time also means that a phone left open keeps costing money.

Leaks that give the real identity away

A proxied browser can still reveal the machine behind it. Three leaks are worth checking every time.

WebRTC

WebRTC powers video calls in the browser. To set up a call it asks a STUN server, over UDP, for the device's public address. An HTTP proxy does not carry UDP, so that request can leave directly, and a script on the page can read the real IP. Firefox can switch WebRTC off in about:config. Chrome needs an extension or a managed policy. Antidetect browsers usually offer a WebRTC setting per profile.

DNS

Chapter 3 covered the SOCKS5 lookup problem and the socks5h:// fix for scripts. Browsers and antidetect profiles on SOCKS5 need the same care. A DNS leak test run inside the profile should show a resolver near the proxy, not the local internet provider.

Timezone and language

A page can read the browser's timezone and language list with two lines of JavaScript. A Frankfurt IP with a Chicago clock and English-only language headers does not add up. Set both to match the exit location. In Playwright that is new_context(locale="de-DE", timezone_id="Europe/Berlin").

One rule sits behind all three fixes. Every signal a site can read should describe the same person in the same place.

Checking the setup with ProxyLook's free tools

Run this check inside each new profile or device before logging in to anything.

1. Confirm the exit IP. Open What Is My IP. The IP, location, ISP and ASN should belong to the proxy, not the local connection.
2. Test for a WebRTC leak. Open the WebRTC Leak Test. Any public address other than the proxy's is a leak.
3. Read the user agent. Paste it into the User-Agent Parser. The browser, engine, system and device should match what the profile claims to be.
4. Look up a new proxy before assigning it. The Proxy Checker returns the country, ASN, ISP and network type for a proxy IP.
5. Check the fit. The Compatibility Checker suggests which proxy type fits a target site and use case.

Repeat the first two steps after every browser update or proxy change. A leak that appears in month three does the same damage as one on day one.