this post was submitted on 24 Jul 2026
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Tesseract is a web client for Lemmy that was found to be secretly and arbitrarily blocking users, communities and even entire instances. You can see if you're one of the kool kidz by running

curl -s https://tesseract.dubvee.org/tesseract/api/system/policy | base64 -d | gunzip > policy.json

and grepping your name / instance. Further details can be found in this post.

The poem above is adapted from Bertolt Brecht's The Burning of the Books, which can be read here. If you would rather read it in the original German, go here.

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[–] HiddenLayer555@lemmy.ml 10 points 6 hours ago

Weird how it's never the tankie instances doing the most blatantly authoritarian shit on Lemmy

[–] Pandantic@midwest.social 3 points 7 hours ago (1 children)

😭 I'm too lib to be banned. I just dont post enough prolly. I didn't even know what tesseract was until today. I think I've heard of it but I almost always use the Thunder app. And I know Hexbear isn't censored for me. However, I did wonder if my instance admin was because I saw him on the list but haven't heard from him in a while.. @seahorse@midwest.social u good? We dont have to worry about tesseract, right?

[–] seahorse@midwest.social 3 points 6 hours ago (1 children)

Hi, I didn't know what this was til now

[–] Pandantic@midwest.social 3 points 5 hours ago

cool, cool. I thought we were good but it doesn't hurt to check.

[–] VeldtSchema@lemmy.ml 3 points 7 hours ago

The Captain whatever dude is a loser. Wow.

[–] Arcanepotato@crazypeople.online 10 points 11 hours ago* (last edited 10 hours ago) (1 children)

It makes no sense because some A+ comrades are not blocked but I am? It must be the veganism.

Edit: oh darn, another comment says it's likely because I have the same username on different instances. I thought that was the least shady way to do things?

Some of us don't know how to use computers and didn't realize how the fediverse worked at first 🥲

[–] eldavi@lemmy.ml 1 points 3 hours ago

... didn’t realize how the fediverse worked at first

Same here and all if my accounts are easily regex-able so the hard coded blocks definitely have something to do w your ability to be received by the normies.

[–] davel@lemmy.ml 20 points 12 hours ago (1 children)

I’m hard-coded into both Tesseract and Piefed.

[–] dessalines@lemmy.ml 11 points 9 hours ago
[–] davel@lemmy.ml 7 points 10 hours ago (1 children)

Wow. Guess what existed yesterday but not today?

I was about to show how the repo version and the dubvee version of the obfuscated banlists are somewhat different from each other, but it’s no longer possible now that the repo has been deleted.

git diff --no-index \
    <(curl -sL https://github.com/asimons04/tesseract/raw/refs/heads/main/static/data/policy.dat \
        | base64 -d | gunzip | gron) \
    <(curl -sL https://tesseract.dubvee.org/tesseract/api/system/policy \
        | base64 -d | gunzip | gron)
[–] emergencyfood@sh.itjust.works 3 points 10 hours ago (1 children)

Interesting. I'm guessing the repo version is publicly viewable, but the dubvee version is the one actually implemented?

[–] davel@lemmy.ml 3 points 9 hours ago* (last edited 9 hours ago)

I couldn’t say. Perhaps the dubvee version was from an earlier git commit. There’s no way to know without a copy of the deleted repo. It might be deducible from @db0@lemmy.dbzer0.com’s fork, but it’s not worth the time & effort. https://github.com/db0/tesseract

[–] emergencyfood@sh.itjust.works 19 points 13 hours ago (3 children)

Get yar medals here!

For the lucky ones indirectly blocked by Tesseract (instance ban / regex):

For the elite few who pissed them off enough to be banned by full name:

[–] grue@lemmy.world 5 points 10 hours ago (1 children)

IMO first and second class should be reversed because being banned by regex implies the guy cared enough to make sure he got all your alts.

[–] emergencyfood@sh.itjust.works 3 points 10 hours ago

I don't think that's the case. I haven't made any alts and still am regex blocked.

[–] CultLeader4Hire@lemmy.world 5 points 12 hours ago (1 children)

I know I’m banned but how would I know which one?

[–] emergencyfood@sh.itjust.works 5 points 12 hours ago (1 children)

The list has been mirrored at https://file.garden/amIRhTctI0qld2r5/policy.json

You aren't banned by name, only by regex :-(

[–] davel@lemmy.ml 5 points 12 hours ago* (last edited 12 hours ago) (2 children)

Most of the regex bans are for those with user accounts on multiple instances under the same name. Extreme example: https://lemmy.ml/search?type=Users&q=cm0002

JSON isn’t especially greppable, which is why I often pipe them through gron.

[–] gary_host_laptop@lemmy.ml 2 points 12 hours ago (1 children)

so essentially the only real blocks are the ones in the user list?

[–] davel@lemmy.ml 4 points 12 hours ago* (last edited 10 hours ago)

Both lists are blocklists, it’s just that one is processed as literal matches and the other as regular expression matches.

[–] goferking0@lemmy.sdf.org 1 points 12 hours ago

Did that user even make the list like on piefed.

[–] gary_host_laptop@lemmy.ml 16 points 14 hours ago (1 children)
[–] gary_host_laptop@lemmy.ml 13 points 14 hours ago (4 children)
[–] BrainInABox@lemmy.ml 2 points 4 hours ago

Hell yeah, me too.

[–] anotherspinelessdem@lemmy.ml 3 points 8 hours ago

Fucking LEGEND

[–] 4am@lemmy.zip 3 points 10 hours ago

I’m 12th user regex, which means he wanted me banned from everywhere.

Except it looks like that list is sorted alphabetically…

[–] raspberry_confetti@lemmy.ml 9 points 14 hours ago

Showoff 😡

[–] 9point6@lemmy.world 9 points 14 hours ago (1 children)

This is a bit of a misread from where I can see

There's more people upset about not being on the list

[–] raspberry_confetti@lemmy.ml 6 points 14 hours ago (1 children)

We just have to post harder

[–] CultLeader4Hire@lemmy.world 4 points 12 hours ago

WAKE UP SHEEPLE!!

[–] carotte@lemmy.blahaj.zone 8 points 14 hours ago* (last edited 14 hours ago) (1 children)

"^carotte$" is in the user regexes but i'm not in the user list... hmmm.

looking at the list i'm wondering how is it possible that any content from lemmy showed up on tesseract lol. why did they block "article is paywalled"???

[–] VeldtSchema@lemmy.ml 4 points 7 hours ago

Because the loser behind this hates people that are not okay with the enshittification of the internet, of course!

The whole thing screams he is not okay with conflict-So he hides anything that he considers conflictive. There is no war in Ba Sing Se moment.