Your files stay on your device

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.
 (/network/my-ip)
- Live DNS lookup

Resolve a name over DNS-over-HTTPS JSON (Cloudflare or Google): records, TTLs, status, flags.
 (/network/dns)
- RDAP lookup

Registry data for domains, IPs, and AS numbers over RDAP: events, status, nameservers.
 (/network/rdap)
- HTTP timing probe

Repeated timed GETs against an https URL: TTFB, totals, and Resource Timing phase splits.
 (/network/http-timing)
- WebSocket tester

Connect a WebSocket in your browser: subprotocols, frames, close codes, timeouts.
 (/network/ws-tester)

Subnets and addresses

- IPv4 subnet calculator

Network, broadcast, mask, wildcard, host counts. Exact BigInt math on your CIDR.
 (/network/ipv4-subnet)
- IPv6 prefix calculator

First and last address, exact 2^n capacity, arpa prefix, for any prefix from /0 through /128.
 (/network/ipv6-subnet)
- VLSM planner

Allocate unequal subnets from one base, every sizing decision visible as a step.
 (/network/vlsm)
- Subnet split & aggregate

Split a block into equal children, or merge siblings back. Preconditions are refused honestly.
 (/network/subnet-split)
- CIDR overlap check

Pairwise overlaps and uncovered gaps over pasted CIDR blocks.
 (/network/cidr-check)
- IP range classifier

Private, reserved, or special-purpose, checked against a dated IANA registry snapshot.
 (/network/ip-classify)
- IP number forms

IPv4/IPv6 as integer, hex, and binary, exact in both directions.
 (/network/ip-numbers)
- IPv6 expand & compress

Expand, compress, and canonicalize IPv6 with RFC 5952 rules applied and named.
 (/network/ipv6-format)
- ULA generator

RFC 4193 unique local addresses plus a /48 planner.
 (/network/ula)
- MAC & EUI-64

Every MAC notation, the U/L and group bits named, the EUI-64 and its fe80:: derivation.
 (/network/mac-eui64)

Reference

- Port reference

A dated, curated IANA port snapshot: search numbers, names, and protocols.
 (/network/ports)
- DNS explainer

dig transcripts and zone records explained line by line; no resolver.
 (/network/dns-explain)
- Bandwidth calculator

Transfer time at a line rate: exact fractions, both unit bases, no fake efficiency.
 (/network/bandwidth)
- MTU & MSS calculator

Versioned overhead table for VLAN, PPPoE, GRE, VXLAN, WireGuard, IPsec.
 (/network/mtu)

Your files are processed on your device. The few tools that talk to the internet say so before they do.

Canonical HTML: https://nutter.tools/network/
Markdown version: https://nutter.tools/network/index.md
Plain-text version: https://nutter.tools/network/index.txt
Agent index: https://nutter.tools/llms.txt