Live · Beijing node · refreshed weekly
Which parts of your stack break first in China.
Stack Break Lab loads every third-party dependency the way your product does — from a mainland China node — then reports what arrives, what stalls, and what's blocked outright.
The problem
Your app assumes the open internet. China doesn't.
The moment a request leaves for Google, Auth0, or YouTube, the Great Firewall decides whether it returns. Some calls stall for ten seconds; some never resolve. Your users just see a page that won't finish loading — and you never find out from outside China.
Fonts & icons
Text renders invisible or jumps as web fonts time out behind the firewall.
Auth & identity
Sign-in widgets and CAPTCHAs hang, locking real users out of your product.
Analytics & tags
Tag loaders block the main thread while they wait on hosts that never answer.
Maps, media, embeds
Maps, video, and embeds collapse into empty boxes with no fallback.
The method
One method, run from the inside.
Every verdict on this site comes from the same pipeline, executed on real mainland China infrastructure — not a VPN, not a guess.
Probe
curl and dig hit every dependency from an Alibaba Cloud Beijing node, recording DNS, connect, and total time.
Browser
Playwright loads each single-dependency demo page and records what actually fails in a real browser.
Live verdicts
One dependency per page.
Each page loads exactly one integration the way a normal product would. The chips below show the latest verdict straight from the most recent run.
Fonts & icons 3 dependencies
Auth & identity 3 dependencies
Analytics & tags 2 dependencies
Maps, media, embeds 3 dependencies
Deep dive
The Firebase stack, end to end.
A separate probe kit measures the whole Firebase stack from the same node — — of — probes are currently blocked. Each card opens the matching section of the Firebase results.
Latency
Where China lands on Netlify.
A real Netlify site — steady-marshmallow-cb991f.netlify.app (hosting, Functions, Edge Functions, Forms, Identity, Blobs, Image CDN) — is probed from the same node. The Netlify edge serving these requests reports —. — page resources measured; heaviest load —. See the latency results.
Deep dive
The Vercel stack, end to end.
A real Vercel site — project-silk-eta-17.vercel.app (Hosting, Functions, Edge Middleware, Cron, Blob, KV) — is probed from the same node. — of — probes are currently blocked. Blob store: Hong Kong; Redis: Singapore. Open the Vercel results.
Latency
Where China lands on Vercel.
The same demo site is measured for page-resource weight and load latency. The Vercel edge serving these requests reports —. — resources measured; heaviest load —. See the latency results.
Before you ship
Test your stack before your users do.
See the full table of verdicts, read the write-up, or run the probes yourself from your own China node — every script is open source.