China Firewall Tester: 5 Free Tools to Check If Sites Are Blocked (2026)

“Is this site blocked in China?” is a simple question with an annoying answer: it depends.

Sometimes the Great Firewall (GFW) blocks an entire domain. Sometimes it blocks only a subdomain, a CDN hostname, an IP range, or a specific protocol (hello, HTTPS handshake problems). Sometimes your website is not blocked—it’s just painfully slow because one tiny dependency loads from Google, and that dependency is blocked.

This guide gives you the practical toolkit to answer the question with confidence:

• A quick, non-scary explanation of how the GFW blocks traffic
• 5 free China firewall tester tools (with step-by-step instructions and “what the screenshot should look like” descriptions)
• How to interpret common results (DNS poisoning vs TCP reset vs timeout vs “it works but it’s slow”)
• A short list of commonly blocked sites (so you can stop re-testing YouTube)
• Realistic alternatives: VPNs, mirrors, and “stop using blocked dependencies”

If you want the easiest traveler setup (VPN + backup apps + offline plans), start here: Best VPN for China (2024).

Quick Answer

To test a website from China, run checks that cover DNS, HTTP/HTTPS reachability, and page load dependencies from multiple China locations. One “works for me” result is not enough—China is big, and network paths vary by province and ISP.

If your tool results show:

• DNS resolves to a weird IP (or different from global): likely DNS interference.
• TCP reset / connection reset: likely active blocking.
• Timeout from multiple China nodes but works globally: likely blocked or heavily filtered.
• Homepage loads but assets fail: often not a “site block,” but blocked third-party resources.

Table of Contents

• Why You Need to Test (GFW in 90 Seconds)
• Before You Test: Define “Works in China”
• 5 Free China Firewall Tester Tools (Step-by-Step)
  • Tool 1: GreatFire Analyzer
  • Tool 2: GFW Report
  • Tool 3: 17CE Multi-Node Website Test
  • Tool 4: BOCE (Multi-Node Monitoring)
  • Tool 5: ChinaZ / ITDog Ping + DNS Checks
• How to Interpret Results (Common Patterns)
• Commonly Blocked Websites (Short List)
• Workarounds and Alternatives
• FAQ
• CTA: Set Up VPN Before You Fly

Why You Need to Test (GFW in 90 Seconds)

The Great Firewall isn’t one giant “blocked list.” Think of it as a bundle of techniques used by ISPs and network operators to make certain traffic unreliable or inaccessible.

Here are the big ones that show up in real-world tests:

1) DNS interference (aka “your domain resolves to nonsense”)

Sometimes a user in China asks: “What IP is example.com?” and gets:

• the wrong IP,
• no response,
• or a response that changes depending on resolver and network.

This creates classic symptoms:

• your site works on some networks and not others,
• your site works with a custom DNS but not default,
• your monitoring says “up” but real users can’t reach it.

2) IP blocking (the address itself is blocked)

If the IP range is blocked, even correct DNS won’t save you. This can happen if you share IP space with other “unlucky” sites (common on shared hosting/CDNs).

3) SNI / TLS / HTTPS filtering

Modern websites use HTTPS. Filtering can happen at the handshake level, meaning:

• the browser tries to connect,
• the handshake fails,
• users see endless loading or a generic “site can’t be reached.”

4) Keyword / URL filtering and resets

Some filtering can be request-based. You might see:

• connection resets,
• partial loads,
• certain pages failing while the homepage works.

5) Dependency blocking (your site is “fine,” but it depends on blocked stuff)

This is the sneakiest one.

Your server is reachable, but your site calls:

• Google Fonts
• Google Analytics scripts
• YouTube embeds
• reCAPTCHA
• Facebook pixels

Result: the page appears broken, forms don’t submit, and users assume your site is blocked.

Before You Test: Define “Works in China”

Decide what “works” means for your goal:

• Reachable: Does the domain respond to HTTP/HTTPS from China?
• Usable: Does the page load in under 5–8 seconds on mobile networks?
• Functional: Do forms, login, payments, and maps work without blocked dependencies?
• Stable: Does it work from different ISPs (China Mobile / Unicom / Telecom) and regions?

If you’re a traveler, “works” often means: “Can I open it on hotel Wi‑Fi and on my mobile data?”

If you’re a website owner, “works” should include: “Can users complete the action that makes me money?”

5 Free China Firewall Tester Tools (Step-by-Step)

Important note: free tools are not perfect. Your goal isn’t “one tool says blocked.” Your goal is consistent evidence from multiple angles.

Tool 1: GreatFire Analyzer

What it’s good for:

• Quick “is this domain historically blocked?” signal
• Easy-to-understand results

How to use it:

1. Open GreatFire Analyzer in your browser.
2. Enter your domain (example: example.com).
3. Run the check and wait for results.

What the “screenshot” should look like:

• A simple results page that shows reachable vs blocked status, often with a time indicator.
• Some versions show a history-style display or a summary badge.

How to read it:

• If it flags your domain as blocked, that’s a strong hint—but still verify with live multi-node tests below.
• If it says “OK,” don’t celebrate yet. Your homepage might load while your assets fail.

Tool 2: GFW Report

What it’s good for:

• A second independent signal
• Testing the same domain with a different approach than GreatFire

How to use it:

1. Open the GFW Report site in your browser.
2. Paste your URL (include https:// if your site redirects aggressively).
3. Run the test and note the output.

Screenshot description:

• A results view showing multiple test lines (DNS, connect, HTTP/HTTPS) with pass/fail indicators.

How to read it:

• If DNS fails but connect succeeds on raw IP, suspect DNS interference.
• If connect fails consistently, suspect IP or handshake blocking.

Tool 3: 17CE Multi-Node Website Test

What it’s good for:

• Realistic checks from many China regions
• Seeing regional differences (north vs south, different ISPs)

How to use it:

1. Open 17CE.
2. Choose “website speed test” / multi-node test.
3. Enter your URL.
4. Select nodes (pick a mix: Beijing/Shanghai/Guangzhou/Chengdu; and if possible, choose different carriers).
5. Run the test.

Screenshot description:

• A map or list of China cities with green/red markers.
• A table with columns like DNS time, connect time, TTFB, total time, and HTTP status.

How to read it:

• Many nodes timeout: strong “blocked or unreachable” signal.
• Some nodes green, some red: could be region/ISP variance, routing, or partial filtering.
• All nodes succeed but slow: not blocked; you likely need China-optimized hosting/CDN.

Tool 4: BOCE (Multi-Node Monitoring)

What it’s good for:

• Similar to 17CE, often with additional node types
• Useful for repeated spot checks over time

How to use it:

1. Open BOCE and choose a website check (HTTP/HTTPS).
2. Enter your URL.
3. Select multiple China nodes.
4. Run the test and export/record results.

Screenshot description:

• A matrix-style result view: rows = cities/nodes, columns = DNS/connect/SSL/HTTP.

How to read it:

• Repeated SSL handshake failures can indicate TLS filtering or a misconfigured TLS chain that browsers in China don’t like.
• If HTTP works but HTTPS fails, suspect TLS/SNI/handshake issues (or a bad certificate chain).

Tool 5: ChinaZ / ITDog Ping + DNS Checks

What it’s good for:

• Fast “network-level” debugging
• Comparing DNS answers and reachability

How to use it (general flow):

1. Open a ping/DNS tool (ChinaZ or ITDog are common).
2. Run DNS lookup from China nodes.
3. Run ping or TCP ping (if available) to your domain/IP.
4. Compare results across locations.

Screenshot description:

• A list of nodes with returned IPs.
• A ping results table showing packet loss and latency (or a note that ICMP is blocked).

How to read it:

• Ping can be misleading (many servers block ICMP). Treat ping as “hint,” not final verdict.
• DNS answers that differ wildly from global resolvers are a red flag.

How to Interpret Results (Common Patterns)

Here’s the cheat sheet for the most common “china firewall tester” outputs.

A 10-Minute Testing Workflow (Do This Every Time)

If you only follow one part of this guide, follow this. It turns “random testing” into a repeatable workflow.

Step 1: Test the domain from 2 different block-check tools

• Run GreatFire Analyzer
• Run GFW Report

Goal: get a quick “likely blocked vs likely not blocked” signal.

If both say “blocked/unreachable,” you probably have your answer. If results disagree, continue.

Step 2: Test from multiple China nodes (at least 6)

Use 17CE or BOCE and pick a mix of:

• Beijing (north)
• Shanghai (east)
• Guangzhou/Shenzhen (south)
• Chengdu/Chongqing (west)
• and if possible, a few different ISPs

Goal: confirm whether failures are widespread or region-specific.

Step 3: Separate “server unreachable” from “page broken”

Run two tests:

1. Reachability test: does https://example.com return an HTTP status (200/301/403/etc.)?
2. Page function test: does the page load normally and can you complete the key action?

If you’re a website owner, the “page function test” is where you’ll discover the real villain: blocked dependencies.

Step 4: Check dependencies (the 60-second sanity check)

Open your site in a normal browser and look for obvious third-party calls. The usual suspects:

• fonts.googleapis.com
• www.google-analytics.com
• www.googletagmanager.com
• www.youtube.com
• www.google.com/recaptcha

If any of these are in your critical path, your site may look “blocked” even when it isn’t.

Step 5: Decide what “fixed” means

For travelers:

• “I can access it reliably on hotel Wi‑Fi and mobile data.”

For site owners:

• “A user in China can load the page and complete the main action without timeouts.”

This matters because the fix for “blocked” and the fix for “slow/broken” are different.

Pattern A: DNS looks wrong

Symptoms:

• China nodes resolve example.com to a strange IP.
• The resolved IP doesn’t match your CDN/origin.
• Some tools show different IPs for different nodes.

Likely cause:

• DNS interference or resolver-level issues.

What to do:

• Ensure you use a reputable DNS provider with China-friendly routing.
• Avoid CNAME chains that point to blocked domains.
• If you control the client (travelers), try switching DNS—but for website owners, you must fix it server-side.

Pattern B: TCP reset / connection reset by peer

Symptoms:

• Tools report “RST” or “connection reset.”
• You see intermittent successes but many hard resets.

Likely cause:

• Active filtering.

What to do:

• For travelers: use a VPN (and install it before arrival).
• For site owners: consider China-specific hosting/CDN, or a mirror domain for mainland users.

Pattern C: Timeouts everywhere in China, fine elsewhere

Symptoms:

• Multiple China nodes fail consistently.
• Global nodes succeed.

Likely cause:

• IP block, TLS/SNI block, or upstream filtering.

What to do:

• Confirm with multiple tools and regions.
• If you use a CDN, test an alternate IP range/provider.
• Audit dependencies (see Pattern E).

Pattern D: Homepage loads, but the site feels broken

Symptoms:

• Text loads but styling is missing.
• Images don’t load.
• Login buttons do nothing.
• Captcha never appears.

Likely cause:

• Blocked third-party resources (Google-hosted JS, YouTube embeds, reCAPTCHA, etc.).

What to do:

• Replace blocked dependencies with China-friendly alternatives.
• Self-host critical JS/CSS assets.
• Use a captcha solution that works in China.

Pattern E: It works, but it’s painfully slow

Symptoms:

• Tests succeed but show 8–20 second load times.
• High packet loss or big latency from China nodes.

Likely cause:

• Not blocked—just poor China routing.

What to do:

• Use a CDN with China POPs (or optimize with Hong Kong + smart routing).
• Reduce third-party calls.
• Consider ICP filing if you plan to host inside mainland China (details in our technical guide below).

Example Results (So You Don’t Overthink It)

Sometimes it helps to see what “normal” looks like.

Example 1: “Blocked” looks like widespread timeouts/resets

You test 10 China nodes:

• 8 timeout
• 2 show connection reset
• all global nodes succeed instantly

Interpretation: very likely blocked or heavily filtered.

Best next step:

• For travelers: VPN.
• For site owners: investigate IP/CDN ranges, consider mirror strategies, and audit blocked dependencies.

Example 2: “Not blocked, but broken” looks like partial loads

Your site returns HTTP 200 from China nodes, but the page:

• has no styling
• has missing fonts
• has buttons that do nothing

Interpretation: your domain likely isn’t blocked, but your assets or scripts are.

Best next step:

• self-host critical CSS/JS/fonts
• remove blocked third-party scripts from the critical path

Example 3: “Not blocked, just slow” looks like high TTFB and long total time

China nodes succeed, but:

• TTFB is 2–6 seconds
• total load time is 10–20 seconds

Interpretation: routing/performance issue.

Best next step:

• CDN optimization
• reduce payload and third-party calls
• consider Hong Kong/Singapore origin strategy if you can’t host in mainland China

Commonly Blocked Websites (Short List)

If you’re testing these, you can usually skip the tools and accept reality:

• Google services: Google Search, Gmail, Google Maps, Google Drive, YouTube
• Meta services: Facebook, Instagram, WhatsApp
• X (Twitter)
• Wikipedia (availability varies; often unreliable)
• Many Western news sites (varies by outlet/time)
• Some developer tools and social platforms (varies over time)

Important: this list changes. The point is not to memorize it—the point is to know how to test reliably.

Workarounds and Alternatives

Option 1: Use a VPN (traveler-friendly)

If you’re a traveler trying to access blocked sites, a VPN is usually the simplest solution—if you set it up before arrival.

Practical tips:

• Install 1–2 VPN apps before you fly (one can fail; redundancy is sanity).
• Download offline instructions and login credentials.
• Test your VPN at home before travel.

VPN guides:

• Best VPN for China (2024)
• WannaFlix vs ExpressVPN in China
• Saily vs WannaFlix VPN in China

Option 2: Use mirrors or alternate domains (site-owner strategy)

Some organizations provide mirror sites or alternate domains to improve reachability. This is common for documentation sites and downloads.

If you do this:

• keep mirrors clearly branded to prevent phishing confusion,
• avoid linking to blocked dependencies (or the mirror will “work” but still break),
• consider region-specific routing (China users to China-friendly endpoints).

Option 3: Replace blocked dependencies (most underrated fix)

If your website is not explicitly blocked, the fastest win is often:

• self-hosting assets,
• removing Google-hosted fonts/scripts,
• replacing reCAPTCHA,
• avoiding embedded blocked media (use local video hosting or provide a fallback).

Option 4: China-optimized hosting/CDN + compliance (advanced)

If your business depends on mainland users, you’ll eventually face:

• routing optimization (China POPs),
• content delivery strategy,
• and potentially ICP filing if hosting inside mainland China.

That’s outside the scope of this traveler-first guide, but we cover the website-owner angle in: 5 Best Tools to Test If Your Website Works in China (2026).

Extra Tips (That Save You Hours)

Tip: Test from a real phone in China if possible

If you’re doing serious validation (especially for business websites), tool nodes are helpful but not perfect. Real users experience:

• mobile networks,
• captive portals,
• VPN instability,
• and “app opens embedded webview” weirdness.

If you have a colleague or friend in China, ask them to test:

• on hotel Wi‑Fi
• on mobile data
• and inside at least one Chinese app webview (WeChat is the classic)

Tip: Don’t confuse “blocked” with “rate-limited”

Some services respond with:

• 403 errors,
• bot protection challenges,
• or CAPTCHAs that never load in China.

That’s not always the Great Firewall. Sometimes your own security stack is rejecting China traffic. If you use heavy bot protection, test those flows explicitly.

Tip: Screenshot results for comparison

When you’re troubleshooting, take screenshots of:

• DNS answers from China nodes
• failed error codes (reset vs timeout)
• successful tests from other regions

It makes pattern recognition much easier than “I swear it worked yesterday.”

FAQ

Is this site blocked in China or just slow?

If multiple China nodes can connect and fetch HTTP status codes but load times are high, it’s often “slow,” not “blocked.” If most nodes timeout or reset, it’s likely blocked or heavily filtered.

Why do some China nodes work and others fail?

Different regions and carriers have different routes, caching, and enforcement behavior. Always test multiple cities and ISPs.

Can I trust ping results?

Ping is useful but not definitive. Many servers block ICMP. Prefer HTTP/HTTPS checks and DNS comparisons.

My site loads but my login doesn’t work—why?

Often a blocked dependency (captcha, analytics script, third-party auth). Audit your network requests and replace blocked services.

Do I need an “official China firewall tester”?

No single tester is “official.” Use multiple tools and focus on consistent patterns.

CTA: Set Up VPN Before You Fly

If you’re traveling, the biggest mistake is waiting until you land to solve the Great Firewall. That’s like buying an umbrella after you’re already wet.

Start here:

• Best VPN for China (2024)
• WannaFlix vs ExpressVPN in China

Final reminder: do one quick test before you board the plane—open your VPN, load one blocked site, and confirm it works. Ten seconds of preparation beats ten hours of airport frustration.