Solution
The Lemmy server appears to have a database limit of 255 characters ^[2]^; however, individual instances appear to put their own limits on username length though the frontend ^[3]^ and/or the API ^[4.1][4.2]^.
Original Post
If you know, please also provide relevant documentation.
UPDATE (2025-02-02T06:06Z): I did some brute-force testing, and, at least for sh.itjust.works, it seems that the maximum username length is 50, and the maximum password length is 60 ^[1]^.
References
- "Sign Up". sh.itjust.works. Lemmy. Accessed: 2025-02-02T08:49Z. https://sh.itjust.works/signup.
- When creating an account on sh.itjust.works, the sign-up form will throw this error if the provided password is greater than 60 characters in length.
- @TootSweet@lemmy.world To: ["[SOLVED] What is the maximum username length for a Lemmy account?". "Kalcifer" @Kalcifer@sh.itjust.works. "Lemmy Support" !lemmy_support@lemmy.ml. sh.itjust.works. Lemmy. Published: 2025-02-03T00:54:51Z. https://sh.itjust.works/post/32085936.]. Published: 2025-02-02T05:57:26Z. Accessed: 2025-02-03T00:44Z. https://sh.itjust.works/post/32085936/16442382.
- They pointed to code on GitHub for the Lemmy server which outlines the length of the username data in the SQL database.
- "[SOLVED] What is the maximum username length for a Lemmy account?". "Kalcifer" @Kalcifer@sh.itjust.works. "Lemmy Support" !lemmy_support@lemmy.ml. sh.itjust.works. Lemmy. Published: 2025-02-03T00:54:51Z. Accessed: 2025-02-03T00:46Z. https://sh.itjust.works/post/32085936.
- §"Original Post". ¶2.
[…] I did some brute-force testing, and, at least for sh.itjust.works, it seems that the maximum username length is 50 […]
- The maximum username length for sh.itjust.works was found to be 50 characters by brute-force testing the length limit.
- §"Original Post". ¶2.
- "Andrew" @andrew_s@piefed.social To ["[SOLVED] What is the maximum username length for a Lemmy account?". "Kalcifer" @Kalcifer@sh.itjust.works. "Lemmy Support" !lemmy_support@lemmy.ml. sh.itjust.works. Lemmy. Published: 2025-02-03T00:54:51Z. https://sh.itjust.works/post/32085936.] Published: 2025-02-02T19:57:49Z. Accessed: 2025-02-03T00:59Z. https://sh.itjust.works/post/32085936/16453656.
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curl -L http://lemmy.world/api/v3/site | jq -r .site_view.local_site.actor_name_max_length(26)- The maximum username length for Lemmy.world was found to be 26 characters via an API request.
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curl -L http://sh.itjust.works/api/v3/site | jq -r .site_view.local_site.actor_name_max_length(50)- The maximum username length for sh.itjust.works was found to be 50 characters via an API request.
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Believing a Lemmy developer's claim simply because they are a developer of Lemmy is an appeal to authority, imo. I would still ask for some documentation as proof, or for them to point to functionality within the code, or similar.