How to Check Proxy Quality: IP, Fingerprint, DNS and WebRTC Leak Tests (2026)

Not all proxies are equal. A proxy might connect successfully but still leak your real IP through WebRTC, show a datacenter ASN instead of a mobile carrier, or fail reputation checks that ad platforms run automatically.

Before using any proxy for Facebook Ads, TikTok, scraping, or multi-accounting — test it. This guide covers every meaningful quality check.

Test 1 — Basic IP and Carrier Check

The first check: does the proxy IP belong to a real mobile carrier?

Tools to use:

• ipwho.is — shows IP, ASN, org, country
• ip.sb — simple IP display
• The built-in checker at proxygrow.com/en/#checker

What to look for:

If org shows a cloud hosting company, you have a datacenter proxy disguised as mobile. Real mobile proxies show the actual carrier name.

Test 2 — WebRTC Leak Test

WebRTC is a browser API that can expose your real IP even when a proxy is active. Platforms like Facebook and TikTok use JavaScript WebRTC checks to detect proxy users.

Tools:

• browserleaks.com/webrtc
• ipleak.net

What to check:

Open the tool through your proxied browser. You should see:

• Public IP = your proxy IP (the mobile carrier IP)
• Local IP = either the proxy IP or nothing (if WebRTC is disabled)

If you see your real home IP in WebRTC: the proxy is leaking. Fix this by:

1. Disabling WebRTC in your anti-detect browser settings
2. Setting WebRTC to "Fake" in AdsPower, Dolphin, or GoLogin
3. Using a browser extension like uBlock Origin with WebRTC blocking

A proper mobile proxy will show the carrier IP in both the HTTP and WebRTC checks when WebRTC spoofing is active in the anti-detect browser.

Test 3 — DNS Leak Test

A DNS leak means your DNS queries go through your real ISP instead of the proxy, revealing your actual location.

Tool: dnsleaktest.com — run the "Extended test"

Expected result: DNS servers should appear in the same country as your proxy. If you see your home country's ISP DNS servers — you have a DNS leak.

Fixes:

• Use SOCKS5 in a browser profile with "Proxy DNS" enabled
• Configure system DNS to 1.1.1.1 or 8.8.8.8 when using IKEv2 VPN
• In VLESS + Xray setup: ensure "domainStrategy": "UseIP" is set in the config

Test 4 — IP Reputation Check

IP reputation tells you if the proxy IP has been flagged for spam, abuse, or blacklisted by ad platforms.

Tools:

• mxtoolbox.com/blacklists — checks common email/IP blacklists
• scamalytics.com — proxy and fraud risk score
• ipqualityscore.com — proxy detection score

What you want:

• Fraud score: below 30/100 is good, below 50 is acceptable
• No blacklist hits on major lists
• is_proxy / is_vpn flags should be false or low confidence

Mobile carrier IPs from active SIM cards rarely get blacklisted because they're shared by real mobile users via CGNAT. This is why they have better reputation than residential or datacenter proxies.

Test 5 — TCP/IP Fingerprint (OS Fingerprint)

Advanced platforms (and some DPI systems) check the TCP fingerprint — how your connection looks at the packet level. A server running a proxy will have a Linux server TCP stack. A real mobile device running Android will have a different TCP profile.

Tool: p0f3.com or Wireshark (technical)

What to look for: If the fingerprint shows Linux 3.x/4.x — that's a server. A real mobile proxy with pOSfp technology will show a fingerprint matching a mobile OS.

ProxyGrow uses Passive OS Fingerprint (pOSfp) spoofing via the proxygrow-minirouter component, which modifies TCP/IP parameters at the kernel level to match real mobile device signatures.

Test 6 — Speed and Stability

A proxy that leaks nothing but drops connections every 30 seconds is still unusable.

Test with:

• fast.com — speed test through the proxy
• speedtest.net — if accessible through the proxy

Acceptable benchmarks for mobile proxies:

• Shared plan: 10–50 Mbps download, stable connection
• Premium plan: 50–150 Mbps download, stable connection
• Latency: 30–120ms is normal for mobile carrier networks

High latency (>300ms) or frequent disconnections usually indicate poor carrier signal at the proxy location. Contact support to get an IP rotation — a new IP session may have a better signal.

Quick Checklist

Before using a proxy for any serious task, verify:

• IP belongs to a real mobile carrier (not datacenter)
• WebRTC shows proxy IP or is blocked
• DNS resolves through proxy country
• Reputation score is low (not blacklisted)
• Connection is stable at acceptable speed

All these checks take under 5 minutes. Skipping them can cost you a banned ad account or burned domain.

Testing ProxyGrow Proxies

ProxyGrow's on-site checker at proxygrow.com/#checker runs the IP and WebRTC check automatically. For DNS and reputation tests, use the external tools listed above.

Our mobile proxies use real SIM cards from Ukrainian, Romanian, and Latvian carriers — they pass carrier detection, have clean reputation, and include pOSfp spoofing on Premium plans.