Network tools
IPv4 and IPv6 subnetting, classification, planning, and reference, computed exactly from parsed values rather than a lookup service. The live tools (DNS, RDAP, my-IP, HTTP timing, WebSocket, headers, CORS) touch the network only when you ask them to.
19 tools
Live lookups
- What is my IP
Your public address as the echo endpoints see it: IPv4 and dual-stack, classified.
- Live DNS lookup
Resolve a name over DNS-over-HTTPS JSON (Cloudflare or Google): records, TTLs, status, flags.
- RDAP lookup
Registry data for domains, IPs, and AS numbers over RDAP: events, status, nameservers.
- HTTP timing probe
Repeated timed GETs against an https URL: TTFB, totals, and Resource Timing phase splits.
- WebSocket tester
Connect a WebSocket in your browser: subprotocols, frames, close codes, timeouts.
Subnets and addresses
- IPv4 subnet calculator
Network, broadcast, mask, wildcard, host counts. Exact BigInt math on your CIDR.
- IPv6 prefix calculator
First and last address, exact 2^n capacity, arpa prefix, for any prefix from /0 through /128.
- VLSM planner
Allocate unequal subnets from one base, every sizing decision visible as a step.
- Subnet split & aggregate
Split a block into equal children, or merge siblings back. Preconditions are refused honestly.
- CIDR overlap check
Pairwise overlaps and uncovered gaps over pasted CIDR blocks.
- IP range classifier
Private, reserved, or special-purpose, checked against a dated IANA registry snapshot.
- IP number forms
IPv4/IPv6 as integer, hex, and binary, exact in both directions.
- IPv6 expand & compress
Expand, compress, and canonicalize IPv6 with RFC 5952 rules applied and named.
- ULA generator
RFC 4193 unique local addresses plus a /48 planner.
- MAC & EUI-64
Every MAC notation, the U/L and group bits named, the EUI-64 and its fe80:: derivation.
Reference
- Port reference
A dated, curated IANA port snapshot: search numbers, names, and protocols.
- DNS explainer
dig transcripts and zone records explained line by line; no resolver.
- Bandwidth calculator
Transfer time at a line rate: exact fractions, both unit bases, no fake efficiency.
- MTU & MSS calculator
Versioned overhead table for VLAN, PPPoE, GRE, VXLAN, WireGuard, IPsec.
Your files are processed on your device. The few tools that talk to the internet say so before they do.