DevTools

Subnet calculation, DNS lookup, IP conversion, SSL certificate checks, and more — the networking utilities developers reach for, in one place. Most run in the browser; some use a server API.

IP / Subnet

Subnet Calculator

Compute network/broadcast/host range and mask from an IPv4 CIDR.

CIDR ↔ Range

Convert between CIDR and IP ranges and count the addresses covered.

IP Base Converter

Convert IPv4 between decimal integer, hex, and binary.

IPv6 Compress/Expand

Compress (::) or expand IPv6 addresses and validate them.

MAC Address Tool

Reformat and validate MAC addresses; analyze local/unicast bits.

DNS / Network

DNS Lookup

API

Look up A/AAAA/MX/TXT/NS/CNAME/SOA records.

Reverse DNS (PTR)

API

Resolve the hostname (PTR record) for an IP address.

My IP / Location

API

Show your current public IP and request header info.

Web / Security

HTTP Header Inspector

API

Inspect a URL's response status, headers, and redirect chain.

SSL Certificate Check

API

Check a domain's TLS certificate expiry, issuer, and SAN.

Encoding / Convert

Base64 Encoder

Encode/decode text to and from Base64 (UTF-8 supported).

URL Encoder

URL-encode and decode strings.

JWT Decoder

Decode a JWT's header and payload and check its expiry.

Reference

Port Reference

Search well-known port numbers.