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.

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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