It seems that their service is back up

Do you use Cloudflare?

No we just run our API on heroku and use no custom domain names. For some of us requests are working as normal, but for others every request is failing.

What error are you getting? Because for us it seemed that the Cloudflare <-> HerokuDNS link was down. But even then I was able to access my app from the dashboard (like https://my-app.herokuapp.com/)

If you still have this issue, here's the fix:

1. Go to your Heroku app, copy the DNS-target for your apex (root) domain (the one that looks like "stark-horse-mrp4jeowu9yvwpnnma32x6hd.herokudns.com")

2. Go to https://www.nslookup.io/, put the DNS target

3. Go through all 5 tabs at the top (Cloudflare, Google, Authoritative) - wherever i you see "A" records - I could only see them in "Authoritative"

4. Copy first A record

5. Go to CloudFlare, replace the flattened CNAME / A record you have for your apex domain with this A record IP you copied

6. Your website should work now, but do the same with the other A records you found as well

7. You should probably revert back to whatever you had in Cloudflare, as soon as Heroku is back up

For me the securitytrails.com website just crashes. I put my DNS target: "stark-horse-mrp4jeowu9yvwpnnma32x6hd.herokudns.com", clicked "Run Check" and it seems to redirect to a failed (no CSS) webpage. Anyone else experiencing this?

EDIT: I MANAGED to make it work with this:

https://www.nslookup.io/

Make sure to go through all the tabs at the top (Cloudflare DNS, Google DNS) - for me they were all "no A records found". Only "Authoritative" gave me 3 A records which I successfully managed to use.

That seems to happen when you put in a DNS target that doesn't have any records in SecurityTrails. In that case, it is best to use nslookup

Yeah securitytrails.com was working for me, but went down about 10 mins ago.