Free tool
Open port checker
Check whether a port is reachable from the internet on your own connection - handy after setting up port forwarding, or to make sure something isn't exposed by mistake.
We only ever check the address you're connecting from, one port at a time, with a short timeout - never another address, and never a range.
Do I need open ports for remote access?
Not with RemoteAccessApp: your PCs connect out to our relay, so there's nothing to forward and no port to leave open. Opening Remote Desktop (3389) or VNC (5900) straight to the internet is one of the most common ways PCs get attacked. With no ports to open, what decides how smooth a session feels is your latency and download speed, and the internet speed test for remote access measures both. For what delay and bandwidth each do to a session, see remote desktop lag, explained simply.
Checking from a phone on mobile data checks the phone's connection, not your home's: run it on a device on the network you want to check. To see which public address that network uses, look up your IP address from the same device.