Yes — backstack.app has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 backstack.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3032::6815:3b82 answers · 443✓ 2606:4700:3036::ac43:b185 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. bob.ns.cloudflare.com ✓isla.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://backstack.app/ via 2606:4700:3032::6815:3b82 → 302https://technoviking.cloudflareaccess.com/cdn-cgi/access/login/backstack.app?kid=30fb18ab4d3ea51bd28480eb83f756360c4b98b6bb92c538fb3cbbf5cc05e70f&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6IjE3YzI2NzhlMDIwZjI2MTk1YjE5MmVmMmUxMmI5OGQ4NTY5ZDllMDZjNjhlZWRkNThlZDgyOWE5NjczZDY1M2YifQ.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.sr5ElN23i88xd0GQBTNiDoWd4VcpmDb30bYfPPRYG4hEbTgyk24xSrAjRUD3WGO0UpEQW3FeMPE5UazT3Qkqdh3awFchB74RYHpa8Ko_J-LzjLM0FhyOO99gqHXt0VP25YsfndDkcGKE17fN1QAmcE5yO2ZrNC0UizvpAKCo11b84TJYVf4jwaZHvOUJ0D1-u97X7N2TnkMhZrpqUzkNcRD1j-q3cU_NaIzqJ2PzqC6Cnl1dZgSAwyguiSTh4yQanKIXLxn1wvyADHvgrtGCku8zIPkrHxJrB_ZJK4sMlF7C_b0ApaTgvszPpmg2rvaspOAYjqPO-7Ia99LZ-9F9gw&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/backstack.app.svg)](https://aaaa.bot/backstack.app)

Check again

backstack.app Has IPv6

A (IPv4)	104.21.59.130 172.67.177.133
AAAA (IPv6)	2606:4700:3032::6815:3b82 2606:4700:3036::ac43:b185

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: backstack.app
Measured 2026-11-11 20:46:53 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    104.21.59.130, 172.67.177.133
AAAA (IPv6): 2606:4700:3032::6815:3b82, 2606:4700:3036::ac43:b185

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: backstack.app has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3032::6815:3b82: answers (TCP 443)
    2606:4700:3036::ac43:b185: 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://backstack.app/ via 2606:4700:3032::6815:3b82 -> HTTP 302, certificate: valid
    https://technoviking.cloudflareaccess.com/cdn-cgi/access/login/backstack.app?kid=30fb18ab4d3ea51bd28480eb83f756360c4b98b6bb92c538fb3cbbf5cc05e70f&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6IjE3YzI2NzhlMDIwZjI2MTk1YjE5MmVmMmUxMmI5OGQ4NTY5ZDllMDZjNjhlZWRkNThlZDgyOWE5NjczZDY1M2YifQ.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.sr5ElN23i88xd0GQBTNiDoWd4VcpmDb30bYfPPRYG4hEbTgyk24xSrAjRUD3WGO0UpEQW3FeMPE5UazT3Qkqdh3awFchB74RYHpa8Ko_J-LzjLM0FhyOO99gqHXt0VP25YsfndDkcGKE17fN1QAmcE5yO2ZrNC0UizvpAKCo11b84TJYVf4jwaZHvOUJ0D1-u97X7N2TnkMhZrpqUzkNcRD1j-q3cU_NaIzqJ2PzqC6Cnl1dZgSAwyguiSTh4yQanKIXLxn1wvyADHvgrtGCku8zIPkrHxJrB_ZJK4sMlF7C_b0ApaTgvszPpmg2rvaspOAYjqPO-7Ia99LZ-9F9gw&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/9XrNOG87By

Permanent link: aaaa.bot/r/9XrNOG87By · How we measure

Checked 2026-11-11 20:46:53 UTC. Full DNS report: dns.pizza/domain/backstack.app · Age, certificate and blocklists: how.is/backstack.app · JSON: /api/v1/backstack.app