Yes — esl-tools.app has IPv6.

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

IPv6 readiness

Website, mail and DNS all work over IPv6.

Website over IPv6 esl-tools.app has 2 IPv6 addresses and answers on every one we tested. ✓ 2606:4700:3034::ac43:9dfd answers · 443✓ 2606:4700:3036::6815:4255 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. emerson.ns.cloudflare.com ✓kiki.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://esl-tools.app/ via 2606:4700:3034::ac43:9dfd → 302https://eslfuels.cloudflareaccess.com/cdn-cgi/access/login/esl-tools.app?kid=1c3d400f3382762864d5c3343159ee8628c7ddb3d40730919124dc7591d4859e&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6IjhhZTliNjM0NGU4NGVmNTkyNDAzMDExZGU2ZDI4N2RjY2JmMzYxYTFhMjBkYTIzYWZiNjIzNDhhYmZiZmJlMzUifQ.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.WWP8NzpLv8nKYvxqZQSnvyBJatUBDOfrWLyV4iIlcVEAJPHFpFjMgLOOouN-1msyukZ-Uuv3FNxXyFvM7BbgxSNX9Pam3oPbjUuCJIffXjlJqU94AK3mrG_Ab6y3mQyMC7V6RIO8pvVR4M0LJkhzg1UQFsm3y1zInnglzp4TCDQ7QerV_cpVHkydk69ePQnUEDUc1VSqodfp3bThgD01bZWnMcLF-83B_3-zwfgGJwxB73AtPxhrACZ28igmuvCJjrRN6WtxAw2c-uR-P3B1W-JTGCAMnPbg4nkWdDv-yEYgh_uOWZxOxtOWoh2jBrJ_mwBqi3nAwJOvaVFXQa8yNg&redirect_url=%2F via 2606:4700:300a::6813:c21d → 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/esl-tools.app.svg)](https://aaaa.bot/esl-tools.app)

Check again

esl-tools.app Has IPv6

A (IPv4)	172.67.157.253 104.21.66.85
AAAA (IPv6)	2606:4700:3034::ac43:9dfd 2606:4700:3036::6815:4255

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: esl-tools.app
Measured 2026-11-11 07:46:41 UTC by aaaa.bot (one server on Fly.io, region iad)

A (IPv4):    172.67.157.253, 104.21.66.85
AAAA (IPv6): 2606:4700:3034::ac43:9dfd, 2606:4700:3036::6815:4255

Readiness grade A: Website, mail and DNS all work over IPv6.
- Website over IPv6: esl-tools.app has 2 IPv6 addresses and answers on every one we tested.
    2606:4700:3034::ac43:9dfd: answers (TCP 443)
    2606:4700:3036::6815:4255: 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://esl-tools.app/ via 2606:4700:3034::ac43:9dfd -> HTTP 302, certificate: valid
    https://eslfuels.cloudflareaccess.com/cdn-cgi/access/login/esl-tools.app?kid=1c3d400f3382762864d5c3343159ee8628c7ddb3d40730919124dc7591d4859e&meta=eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImtpZCI6IjhhZTliNjM0NGU4NGVmNTkyNDAzMDExZGU2ZDI4N2RjY2JmMzYxYTFhMjBkYTIzYWZiNjIzNDhhYmZiZmJlMzUifQ.eyJ0eXBlIjoibWV0YSIsImF1ZCI6IjFjM2Q0MDBmMzM4Mjc2Mjg2NGQ1YzMzNDMxNTllZTg2MjhjN2RkYjNkNDA3MzA5MTkxMjRkYzc1OTFkNDg1OWUiLCJob3N0bmFtZSI6ImVzbC10b29scy5hcHAiLCJyZWRpcmVjdF91cmwiOiIvIiwic2VydmljZV90b2tlbl9zdGF0dXMiOmZhbHNlLCJpc193YXJwIjpmYWxzZSwiaXNfZ2F0ZXdheSI6ZmFsc2UsImV4cCI6MTc5NDM4MzUwMSwibmJmIjoxNzk0MzgzMjAxLCJpYXQiOjE3OTQzODMyMDEsImF1dGhfc3RhdHVzIjoiTk9ORSIsIm10bHNfYXV0aCI6eyJjZXJ0X2lzc3Vlcl9kbiI6IiIsImNlcnRfc2VyaWFsIjoiIiwiY2VydF9pc3N1ZXJfc2tpIjoiIiwiY2VydF9wcmVzZW50ZWQiOmZhbHNlLCJjb21tb25fbmFtZSI6IiIsImF1dGhfc3RhdHVzIjoiTk9ORSJ9LCJyZWFsX2NvdW50cnkiOiJVUyIsImFwcF9zZXNzaW9uX2hhc2giOiI5YjYyMDZlMDg3MWY1MDdkYzJhODA0ZjdhNTM1YTU0NzlhOTVhZDM0NmRiNTU4NjhjNGFhNDBlNzJiZjEyMGNjIn0.WWP8NzpLv8nKYvxqZQSnvyBJatUBDOfrWLyV4iIlcVEAJPHFpFjMgLOOouN-1msyukZ-Uuv3FNxXyFvM7BbgxSNX9Pam3oPbjUuCJIffXjlJqU94AK3mrG_Ab6y3mQyMC7V6RIO8pvVR4M0LJkhzg1UQFsm3y1zInnglzp4TCDQ7QerV_cpVHkydk69ePQnUEDUc1VSqodfp3bThgD01bZWnMcLF-83B_3-zwfgGJwxB73AtPxhrACZ28igmuvCJjrRN6WtxAw2c-uR-P3B1W-JTGCAMnPbg4nkWdDv-yEYgh_uOWZxOxtOWoh2jBrJ_mwBqi3nAwJOvaVFXQa8yNg&redirect_url=%2F via 2606:4700:300a::6813:c21d -> HTTP 200, certificate: valid
DNS answers via DNS-over-HTTPS (Cloudflare). Method: https://aaaa.bot/method
Permanent link: https://aaaa.bot/r/y-or4oflPN

Permanent link: aaaa.bot/r/y-or4oflPN · How we measure

Checked 2026-11-11 07:46:41 UTC. Full DNS report: dns.pizza/domain/esl-tools.app · Age, certificate and blocklists: how.is/esl-tools.app · JSON: /api/v1/esl-tools.app