Yes — flatline.kiwi has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 flatline.kiwi has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3037::6815:1a62 answers · 443✓ 2606:4700:3033::ac43:87d7 answers · 443	yes
Mail servers (MX) have IPv6 No MX records, so mail goes to the domain's own address (implicit MX). It has an AAAA record.	yes
Nameservers have IPv6 2 of 2 nameservers checked have an AAAA record, so IPv6-only resolvers can look the domain up. amir.ns.cloudflare.com ✓opal.ns.cloudflare.com ✓	yes

HTTPS over IPv6 · not part of the grade yet
Loads over IPv6 with a valid certificate after 1 redirect: HTTP 200.

https://flatline.kiwi/ via 2606:4700:3037::6815:1a62 → 302https://red-wave-1aa7.cloudflareaccess.com/cdn-cgi/access/login/flatline.kiwi?kid=463b56e0d011a8455850779eb8cfeaab6bacf1c048aa8380fc99ffa909f36500&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.eViK9BxfCLkbdlj9QBCFxyG6_An9irIWiZAnE6V9AcQkrBp7Mie2T9FBGKJtyboiClvJusxNcrx5onBQnv8bqWNYynf6CdoVpj7fbbJQOycCqTlT7zdA4UH__ypwNqxEU08GvVL9xn1fo8ia-fLMtTRCYAndDwi7jJEtWjaGIOZAcM2q3uCVMCaQLrkuXYTljfd8ySG0KyeV6wn3YeADQrprIkHoMP5UbL9n4ag0gqv8qkoyai8pMIz2fSRoKVig97wIsSCTcQ0CaadU7MvZq_EVG4-nmGFj3WlF54eSgLK4CezUmXbW9zwmzKcjfRrStcyuqwNJcs0yBdxpeNL83w&redirect_url=%2F via 2606:4700:300a::6813:c31d → 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/flatline.kiwi.svg)](https://aaaa.bot/flatline.kiwi)

Check again

flatline.kiwi Has IPv6

A (IPv4)	172.67.135.215 104.21.26.98
AAAA (IPv6)	2606:4700:3037::6815:1a62 2606:4700:3033::ac43:87d7

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: flatline.kiwi
Measured 2026-10-31 07:50:58 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    172.67.135.215, 104.21.26.98
AAAA (IPv6): 2606:4700:3037::6815:1a62, 2606:4700:3033::ac43:87d7

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: flatline.kiwi has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3037::6815:1a62: answers (TCP 443)
    2606:4700:3033::ac43:87d7: answers (TCP 443)
- Mail servers (MX) have IPv6: No MX records, so mail goes to the domain's own address (implicit MX). It 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 after 1 redirect: HTTP 200.
    https://flatline.kiwi/ via 2606:4700:3037::6815:1a62 -> HTTP 302, certificate: valid
    https://red-wave-1aa7.cloudflareaccess.com/cdn-cgi/access/login/flatline.kiwi?kid=463b56e0d011a8455850779eb8cfeaab6bacf1c048aa8380fc99ffa909f36500&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6Ijg2OGFmMjMzMzMwYTk2ZmFjNTUzMTBhMmQyN2E2MmQ1ZWM1YWY5Zjg3ZDBhOTg5OTNhMzk0MjZlMDg1NGI2NzcifQ.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.eViK9BxfCLkbdlj9QBCFxyG6_An9irIWiZAnE6V9AcQkrBp7Mie2T9FBGKJtyboiClvJusxNcrx5onBQnv8bqWNYynf6CdoVpj7fbbJQOycCqTlT7zdA4UH__ypwNqxEU08GvVL9xn1fo8ia-fLMtTRCYAndDwi7jJEtWjaGIOZAcM2q3uCVMCaQLrkuXYTljfd8ySG0KyeV6wn3YeADQrprIkHoMP5UbL9n4ag0gqv8qkoyai8pMIz2fSRoKVig97wIsSCTcQ0CaadU7MvZq_EVG4-nmGFj3WlF54eSgLK4CezUmXbW9zwmzKcjfRrStcyuqwNJcs0yBdxpeNL83w&redirect_url=%2F via 2606:4700:300a::6813:c31d -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/QmYhnHZvfY

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

Checked 2026-10-31 07:50:58 UTC. Full DNS report: dns.pizza/domain/flatline.kiwi · JSON: /api/v1/flatline.kiwi