Selenium

Selenium drives a real browser, so proxy configuration depends on the underlying driver (Chrome / Firefox). Two approaches:

1. No auth — --proxy-server flag (Chrome) or profile setting (Firefox). The browser still prompts for credentials.
2. With auth — install a tiny on-the-fly extension that pre-fills the proxy auth dialog. This is the standard pattern for scraping.

Chrome — with auth via Selenium-Wire

The cleanest option is selenium-wire, a Selenium wrapper that handles proxy auth transparently:

pip install selenium-wire

from seleniumwire import webdriver

USER = "helo_s1a2b3c4d5e-type-res-region-us"
PASS = "PASSWORD"

options = {
    "proxy": {
        "http":  f"http://{USER}:{PASS}@gate.helodata.io:7777",
        "https": f"http://{USER}:{PASS}@gate.helodata.io:7777",
        "no_proxy": "localhost,127.0.0.1",
    }
}

driver = webdriver.Chrome(seleniumwire_options=options)
driver.get("https://ipv4.icanhazip.com")
print(driver.page_source)
driver.quit()

For ISP, swap to http://helo_s1a2b3c4d5e:PASSWORD@198.51.100.42:8000.

Chrome — without selenium-wire (manual auth extension)

If you can't add selenium-wire (e.g. corporate restrictions), build a manifest-v3 extension on the fly:

import os, tempfile, zipfile, json
from selenium import webdriver
from selenium.webdriver.chrome.options import Options

HOST, PORT = "gate.helodata.io", 7777
USER = "helo_s1a2b3c4d5e-type-res-region-us"
PASS = "PASSWORD"

manifest = {
    "manifest_version": 3,
    "name": "helo-proxy",
    "version": "1.0.0",
    "permissions": ["proxy", "webRequest", "webRequestAuthProvider", "<all_urls>"],
    "background": {"service_worker": "bg.js"},
}
bg = f"""
chrome.proxy.settings.set({{ value: {{ mode: "fixed_servers", rules: {{
  singleProxy: {{ scheme: "http", host: "{HOST}", port: {PORT} }}, bypassList: ["localhost"]
}}}}, scope: "regular" }});
chrome.webRequest.onAuthRequired.addListener(
  () => ({{ authCredentials: {{ username: "{USER}", password: "{PASS}" }} }}),
  {{ urls: ["<all_urls>"] }},
  ["blocking"]
);
"""

tmp = tempfile.mkdtemp()
with open(f"{tmp}/manifest.json", "w") as f: json.dump(manifest, f)
with open(f"{tmp}/bg.js", "w") as f: f.write(bg)
ext_path = f"{tmp}/ext.zip"
with zipfile.ZipFile(ext_path, "w") as z:
    z.write(f"{tmp}/manifest.json", "manifest.json")
    z.write(f"{tmp}/bg.js", "bg.js")

opts = Options()
opts.add_extension(ext_path)
driver = webdriver.Chrome(options=opts)
driver.get("https://ipv4.icanhazip.com")

Firefox

Firefox accepts proxy settings directly via FirefoxProfile plus a credential helper. With selenium-wire the same pattern as Chrome works.

Verify

print(driver.execute_script("return navigator.userAgent"))
driver.get("https://browserleaks.com/ip")

Common pitfalls

• Native proxy-auth dialog blocks headless runs. Always use selenium-wire or the extension pattern for headless.
• WebRTC leak — add --disable-features=WebRtcHideLocalIpsWithMdns and/or block media via chrome_options.add_argument("--disable-webrtc") (Brave/Vivaldi flag).
• Proxy not actually used in headless — pre-Chrome-100 used --headless; modern Chrome requires --headless=new for the extension model to work.