Yeah sure. Assuming you are only targeting Lemmy instances (other softwares make this a bit more complicated), A "can interact" with B if:

• A hasn't blocked B
• B hasn't blocked A
• Neither A nor B are on allowlist. If either is on allowlist, it must have explicitly added the other one to its allow list (this is very uncommon, the only big instance using allow lists is hexbear.net)

So, to verify this, you could query the Defed Investigator with the instances you care about, one at a time. Only select the softwares you care about (likely only Lemmy) to make the query faster. Say you wanted to verify the compatibility between lemmy.world and sh.itjust.works (just making an example). Go to https://defed.xyz/check?name=sh.itjust.works&software=lemmy

• ✔ lemmy.world doesn't appear in the "Instances defederated from sh.itjust.works" (this means .world hasn't blocked SJW)
• ✔ lemmy.world doesn't appear in the "Instances defederated by sh.itjust.works" (this means SJW hasn't blocked .world)
• ✔ lemmy.world doesn't appear among the "Instances not allowing sh.itjust.works" (this means .world isn't on allowlist or, if it is, it has explicitly allowed SJW. Again, this is very uncommon)

Also make sure the instance you are looking for isn't among the "Instances that returned errors", of course.

Like @iso@lemy.lol said, can't query from the backend if there is no backend :)

It's all serverless, so this is as good as it gets.

Well, that's probably requires a back-end server and a database.

Hi. Yeah, both are still active, up and running.

User flairs are currently invisible on my instance because I didn't get the chance to update my modded UI to the most recent Lemmy version, but the microservice itself is still perfectly operational.

There seems to be some problem with your instance's API. While the federation page works fine, when polling the defederation API at

https://moist.catsweat.com/api/defederated

I am getting the following error:

{
    "type": "https://tools.ietf.org/html/rfc2616#section-10",
    "title": "An error occurred",
    "status": 500,
    "detail": "Internal Server Error"
}

this also gets interpreted as an error by my tool, which is why the green "Instances defederated by ..." sections is empty.

Not quite, lol.

Some errors will happen, that's inevitable, CORS is a bitch, but if you are getting that many I'm going to make an educated guess and assume there's something wrong with either your device or your connection.

I'm sorry could you please elaborate on why the rest of the Fediverse would be enraged, or how this could be used for harassment? I don't think I follow. I'll admit, I only interact with the Fediverse through Lemmy so maybe there's some dynamics of the Masto-sphere I'm not picking up.

My understanding is that Mastodon admins can choose to hide their /domain_blocks endpoint to either outside users or even to all non admins. (source), and as a matter of fact almost a thousand of the 1700 Mastodon instances I'm querying already do so, so really I can only get the federation status of the few hundred that remain.

I think the admins that prefer not to show their defeds, in fear of harassment, are already hiding them, so it should be ok for me to query the remaining ones.