ネットワークデスク

Network, broadcast, host range and usable hosts from an IP address and mask or CIDR prefix.

Convert between dotted subnet masks, CIDR prefix length, and host counts.

First and last IP address and total address count for a CIDR block. The result stays on this page.

Minimal CIDR list that covers an arbitrary IPv4 start–end range. The result stays on this page.

Allocate variable-length subnets from a parent network and host requirements.

Convert subnet masks to wildcard masks and back, including CIDR prefix length.

Check whether an IPv4 address belongs to a CIDR block. The result stays on this page.

Prefix, network range, and number of subnets for an IPv6 network. The result stays on this page.

Discover subdomains via certificate transparency (crt.sh) from your browser.

Show your public IPv4/IPv6 address and basic connection info. The result stays on this page.

Look up ISP/org details and jump to common abuse reputation sources for an IP.

Identify hardware vendor from a MAC address OUI (curated local database).

Port reference and browser-safe guidance — browsers cannot open arbitrary TCP sockets.

Check HTTP status codes for a URL via a CORS-friendly fetch proxy. The result stays on this page.

Fetch and display response headers for a URL (best-effort via proxy). The result stays on this page.

Trace redirects for a URL when the browser allows it, with a curl fallback.

Check whether a site looks reachable from your browser (with caveats).

Plan non-overlapping channels for 2.4 / 5 / 6 GHz Wi-Fi. The result stays on this page.

Estimate access points needed by floor area and client count. The result stays on this page.

Convert between dBm and milliwatts for RF power planning. The result stays on this page.

Generate a QR code guests can scan to join a Wi-Fi network. The result stays on this page.

Convert between bandwidth units and estimate monthly transfer volume. The result stays on this page.

Estimate time to transfer a file at a given network speed. The result stays on this page.

Convert between GB/month and Mbps for capacity planning. The result stays on this page.