Connectivity & Edge Latency Checker

Server API

Probe connectivity and round-trip latency simultaneously from your local browser and Cloudflare's global edge network across HTTP, WebSockets, gRPC, and TCP ports.

http://
Presets:

Local Browser Vantage

Originating from your local machine/ISP

Ready
Handshake Latency

—

Protocol State

—

Active Protocol:http

Cloudflare Edge Vantage

Global serverless backbone runtime

Ready
Edge-to-Origin Latency

—

Edge POP Node

—

DNS A-Record:Auto-resolved

Multi-Protocol Support

Inspect HTTP/HTTPS, HTTP/3 (QUIC), WebSockets (WS/WSS), gRPC / HTTP2, and raw TCP ports (telnet/netcat) from local and edge vantage points.

Dual-Vantage Diagnostics

Tests connectivity simultaneously from your local browser and Cloudflare’s global edge network to isolate local routing vs global downtime.

HTTP/3, WS & gRPC Traversal

Verifies RFC 9000 QUIC alt-svc advertisements, HTTP 101 WebSocket upgrades, and HTTP/2 grpc-status framing for microservices.

Frequently Asked Questions

How does the HTTP/3 & QUIC probe work?
HTTP/3 runs over UDP using the QUIC protocol (RFC 9000). The probe tests target reachability, inspects Alt-Svc response headers for h3 parameters (e.g. h3=":443"; ma=86400), queries Cloudflare DoH for RFC 9460 HTTPS DNS records (ALPN h3), and compares local browser nextHopProtocol negotiation against Cloudflare Edge telemetry.
How does the WebSocket (WS/WSS) probe work?
The tool initiates a native WebSocket handshake towards your endpoint and measures roundtrip time to HTTP 101 Switching Protocols. It checks whether proxies (like Nginx, Apache, or Cloudflare) correctly forward Upgrade and Connection headers without terminating the connection.
How does the gRPC probe test microservices without proto files?
It sends an HTTP/2 post-probe carrying gRPC framing headers (content-type: application/grpc and TE: trailers). A live gRPC server will reply with HTTP/2 and gRPC trailers (such as grpc-status: 0 or grpc-status: 12 Unimplemented), confirming that an active gRPC daemon is listening.
How does the TCP Port / Telnet checker work?
Just like running "telnet host port" or "nc -zv host port" in a terminal, it initiates raw TCP SYN/ACK handshakes to detect OPEN, CLOSED (RST received), and FILTERED (firewall timeout) ports, while grabbing service banners (e.g. OpenSSH versions or SMTP greetings).
Why does 127.0.0.1 or localhost show "Unroutable" from Cloudflare Edge?
Loopback (127.0.0.1, localhost) and private LAN IPs (10.x.x.x, 192.168.x.x) exist only within your local machine. Public Cloudflare Edge servers across the globe cannot route packets to your private laptop. The tool tests localhost directly from your local browser while correctly marking it unroutable from Edge.
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