Yes — calib.tools has IPv6.

Has both IPv4 (A) and IPv6 (AAAA) addresses.

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 calib.tools has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3031::ac43:ac64 answers · 443✓ 2606:4700:3034::6815:47f3 answers · 443	yes
www over IPv6 www.calib.tools has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3034::6815:47f3 answers · 443✓ 2606:4700:3031::ac43:ac64 answers · 443	yes
Mail servers (MX) have IPv6 Every mail server has an AAAA record. smtp.google.com ✓	yes
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. dorthy.ns.cloudflare.com ✓greg.ns.cloudflare.com ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate: HTTP 200.

https://calib.tools/ via 2606:4700:3031::ac43:ac64 → 200

works

Nothing keeping you from an A

Nothing to fix
Show it off: add the badge to your README.
[![IPv6](https://aaaa.bot/badge/calib.tools.svg)](https://aaaa.bot/calib.tools)

Check again

calib.tools Has IPv6

A (IPv4)	104.21.71.243 172.67.172.100
AAAA (IPv6)	2606:4700:3031::ac43:ac64 2606:4700:3034::6815:47f3

www.calib.tools Has IPv6

A (IPv4)	104.21.71.243 172.67.172.100
AAAA (IPv6)	2606:4700:3034::6815:47f3 2606:4700:3031::ac43:ac64

Browsers on dual-stack networks will usually pick IPv6 here (the "Happy Eyeballs" algorithm races both and prefers v6).

Copy the evidence — a citation-ready record of this measurement

IPv6 measurement: calib.tools
Measured 2026-11-02 22:50:31 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.21.71.243, 172.67.172.100
AAAA (IPv6): 2606:4700:3031::ac43:ac64, 2606:4700:3034::6815:47f3
www AAAA:    2606:4700:3034::6815:47f3, 2606:4700:3031::ac43:ac64

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: calib.tools has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3031::ac43:ac64: answers (TCP 443)
    2606:4700:3034::6815:47f3: answers (TCP 443)
- www over IPv6: www.calib.tools has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3034::6815:47f3: answers (TCP 443)
    2606:4700:3031::ac43:ac64: answers (TCP 443)
- Mail servers (MX) have IPv6: Every mail server has an AAAA record.
- Nameservers have IPv6: 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up.

Reachability = a TCP connection opened on port 443 (or 80).

HTTPS over IPv6 (not graded): Loads over IPv6 with a valid certificate: HTTP 200.
    https://calib.tools/ via 2606:4700:3031::ac43:ac64 -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/2SU_s01H7Y

Permanent link: aaaa.bot/r/2SU_s01H7Y · How we measure

Checked 2026-11-02 22:50:31 UTC. Full DNS report: dns.pizza/domain/calib.tools · Age, certificate and blocklists: how.is/calib.tools · JSON: /api/v1/calib.tools