»» Tools
The network toolbox
Free calculators for everyday work — subnets, encapsulation, optical budgets.
CIDR Calculator
Network address, broadcast, host range and mask for an IPv4 or IPv6 block.
Open the toolVLSM Planner
Split an IPv4 block into subnets of different sizes, without overlap.
Open the toolMPLS / VXLAN / GRE Overhead
Usable MTU remaining after encapsulation — MPLS labels, VXLAN, GRE, 802.1Q.
Open the toolOptical Link Budget
Feasibility of a point-to-point DWDM link: fiber loss, connectors, splices, margin.
Open the toolWho Am I
Your IP address, the AS announcing it, and its RPKI status — detected automatically.
Open the toolBGP Looking Glass
Prefix: who announces it, RPKI, history. ASN: BGP/IRR consistency. AS-SET: member expansion.
Open the toolPrefer an API?
The CIDR calculator is also available over HTTP — free API key, documented rate limits.