A curated list of open source tools, and free services, related to Domain Name System (DNS)
no-ip - Remote access your computer, DVR, webcam, security camera or any internet connected device easily. Dynamic DNS points an easy to remember hostname to your dynamic IP address.
Dynu - We are a free dynamic DNS service provider making your connection easier! We provide fast, easy and affordable domain name registrations. And best of all, you have complete control of your domain name at all times!
dnsExit - Free Dynamic DNS, Managed DNS Services. Rock Solid Enterprise DNS Services while 100% free and maintaining 100% Up Time since 1998
D.U.I.A. - Dynamic Updates for Internet Addressing. DUIADNS is the only dynamic dns provider that allows you to make dynamic IPv6 DNS updates for home network devices directly from your router.
FreeDNS - FreeDNS - Free DNS - Dynamic DNS - Static DNS subdomain and domain hosting
DuckDNS - Duck DNS is a free service which will point a DNS (sub domains of duckdns.org) to an IP of your choice
Zilore - A fast, reliable, and globally accessible DNS hosting service maintained by a team of experts, with amazing capabilities
ClouDNS - ClouDNS makes your DNS faster and secure with Global Anycast DNS Network
SecondDNS - Secondary (slave) DNS with automatic AXFR/IXFR zone sync, NOTIFY, and failover. One-command integrations for cPanel/WHM, Plesk, DirectAdmin, and CyberPanel. Free 3-month trial.
nsupdate.info - nsupdate.info is a free dynamic DNS service. nsupdate.info is also the name of the software used to implement it. If you like, you can use it to host the service on your own server.
NetworkWhois DNS Propagation - Check DNS propagation across multiple public resolvers and locations.
DNS Propagation Checker - Open-source DNS propagation checker with 10+ global DNS servers, supports A/AAAA/CNAME/MX/NS/TXT records. (GitHub)
digga - Free and open-source domain and infrastructure research toolkit for DNS, RDAP, WHOIS, subdomain discovery, email authentication, and TLS certificate inspection. No signup required. (GitHub) Zero Dollar Domains - Catalog of still-free domain/subdomain programs plus a live RDAP hunter for unused cheap TLD names. Honest about forever-free vs year-1 cheap. No expired-.com scrapes.
IntoDNS.ai - AI-powered DNS & email security scanner. Checks SPF, DKIM, DMARC, DNSSEC, blacklists and provides actionable fixes. Free, no signup required.
Relaymetry - Free SPF, DKIM, DMARC and MTA-STS checker. Expands SPF includes to show the real DNS-lookup count and reports the specific fixes. No signup required.
DNSai - AI-era DNS & email-security toolkit: DNS/WHOIS lookup, SPF analyzer, DKIM selector discovery, DMARC and blacklist checks, plus a free API and remote MCP server for AI assistants. Free, no signup required.
net-benchmark - DNS/HTTP/SSL benchmarking CLI with DoH, DoT, DNSSEC validation and full timing breakdown.
DomScan - Domain intelligence with free DNS, WHOIS/RDAP, SSL and DNS propagation lookup tools, plus an API and MCP server for domain availability, valuation and brand protection.
DNS Beacon - Commercial dynamic DNS service that speaks the standard DynDNS2 protocol, so it works with any router, firewall or NAS. Free tier with no periodic re-confirmation, bring-your-own-domain, automatic Let's Encrypt SSL, and IPv4 + IPv6 (AAAA) updates. Hosted in Germany, GDPR-compliant.
proxy-dns-leak-check - Open-source CLI tool to detect DNS leaks when routing traffic through a proxy or VPN. Compares direct vs. proxied DNS resolution for a given host and flags mismatches. Companion to a DNS troubleshooting guide.
Valla DNS - Free, no-signup DNS, WHOIS, propagation (global resolvers with a map), SSL/TLS and email-health (SPF/DKIM/DMARC/MX/blacklist) checker suite.
admintoolkit.io - Free, no-signup browser toolkit for DNS, DNSSEC, MX, SPF, DKIM, DMARC, BIMI, MTA-STS, TLS-RPT, DANE/TLSA, CAA and TLS certificate diagnostics.
Nutilz DNS Lookup - Free browser-based DNS record lookup tool (A/AAAA/MX/CNAME/NS/TXT/SOA) using DNS-over-HTTPS. No signup required.
Nutilz Domain Expiry Checker - Free domain expiry checker. Instantly see when a domain expires, who registered it, registrar and nameservers using WHOIS/RDAP data. Bulk check multiple domains at once. No signup required.
Nutilz DMARC Record Generator - Free DMARC record builder and validator. Generate TXT records with policy (none/quarantine/reject), subdomain policy, rollout percentage, aggregate/forensic report addresses, and SPF/DKIM alignment mode. Also parses and validates existing records. No signup required.
Punycode Converter - Free browser tool for converting internationalized domain names between Unicode and ASCII Punycode in both directions. No signup required.
Domain Hunter - Free, open-source, 100% client-side bulk domain availability checker: queries registry RDAP directly from the browser (no servers, no API keys, no tracking) across 148 TLD zones, with DNS-over-HTTPS corroboration for low-trust ccTLDs, IDN/punycode handling, live registrar prices and CSV/Markdown/TSV export. MIT. (live demo)
If you wish to contribute to this list, just fork, make your changes and send me a pull request, I'll be happy to review all of your suggestions :)