The Ultimate Guide to Firefox Proxy Settings

Unlike Chrome, Firefox has its own built‑in proxy settings. This guide shows how to configure a manual proxy, apply a PAC file, or use your operating system's settings—with screenshots and troubleshooting tips.

System Proxy vs. Firefox‑Specific Proxy

Firefox can either use system proxy settings or override with its own proxy configuration. For per‑browser control, use Firefox's built‑in settings (recommended).

Method 1: Configure Firefox's Built‑in Manual Proxy

  1. Open Firefox, click the menu (≡) → Settings.
  2. Scroll to Network Settings and click Settings….
  3. Select Manual proxy configuration, then enter:
    • HTTP Proxy and Port
    • (Optional) Use this proxy server for all protocols
    • Or set SOCKS Host and Port (SOCKS v5)
  4. (Optional) Add No proxy for domains to bypass.
  5. Click OK, then verify via What's My IP.

Authentication prompts will appear when required by your proxy.

Method 2: Automatic Proxy (PAC File)

  1. Open Settings → Network Settings → Settings….
  2. Select Automatic proxy configuration URL.
  3. Enter your PAC URL (script address) provided by your service.
  4. Click OK, then verify with What's My IP.

Need a custom PAC file? Consider building one with a PAC generator tool (coming soon).

Method 3: Use System Proxy Settings

If you prefer system‑wide control, set your OS proxy and choose Use system proxy settings in Firefox:

❗ Troubleshooting Common Firefox Proxy Issues

Issue 1: "The proxy works in Chrome but not in Firefox."

Firefox does not automatically use OS settings unless selected. Configure Manual proxy or choose Use system proxy settings.

Issue 2: "Sites fail to load over HTTPS."

Check your proxy type and authentication; ensure HTTPS proxy is configured if required. Some security tools can interfere.

Issue 3: "How do I turn off the proxy?"

Open Network Settings → Settings… and select No proxy or revert to Use system proxy settings.

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