Check a decimal IPv4 address

Before an entry, import or submission, this helps teams and individuals catch a malformed value early. Check a decimal IPv4 address.

Check a decimal IPv4 address. The result appears instantly in your browser, ready to copy or reuse, with no account, upload or storage involved.

How to use

Paste the IPv4 address you want to check into the input box; one value at a time gives the clearest answer.
Make sure you are testing a plain dotted-decimal address, without a subnet mask or a port number attached to it.
Start the check and read the message that appears in the result panel.
If the value is rejected, fix the part you typed wrong and run the check again.
You can also import a small text file instead of typing the address by hand.

Example

The sample contains 192.0.2.1, an address set aside for documentation. Run the check and look at the answer it gives: that message is the sort of feedback you would show someone filling in a form, before their address is saved or sent on.

Input

192.0.2.1

Limits and formats

The check covers the shape of a decimal IPv4 address, not whether a machine actually answers at that address.
IPv6 addresses, host names and ranges written with a prefix are outside the scope of this test.
A properly written address can still be private, reserved or wrongly assigned; a valid format says nothing about its use.
For a long list, checking values one by one by hand quickly becomes impractical.

Where processing happens

Everything runs inside your browser on the text you paste or import. No value is transmitted anywhere and nothing remains once you close the tab, so you can test addresses from a private network without exposing them to anyone.

Frequently asked questions

What counts as a valid IPv4 address here?

Four decimal numbers separated by dots, each one standing for a single byte. A correct entry has no letters, no mask and no port, and every group of digits stays inside the limits of one byte.

Does the tool tell me whether the address really exists?

No. It only inspects the way the value is written. A well-formed address may belong to no machine at all, and confirming that something answers at that address calls for other tools entirely.

Can I check several addresses in a row?

Yes, by replacing the value and running the check again each time. The input handles the current entry; for long lists, automating the test in your own script is far quicker than repeating the operation.