In-Game Account Switcher
The In-Game Account Switcher mod allows you to change accounts directly during gameplay without exiting Minecraft or restarting the client.
Dependencies
Fabric: Fabric API (required), Mod Menu (optional) Quilt: QFAPI/QSL (required), Mod Menu (optional) Forge: no dependencies NeoForge: no dependencies
Frequently Asked Questions
Question: Where can I download this mod? Answer: Versions are available for Minecraft 1.18.2, 1.19.2, 1.19.4, 1.20.1, 1.20.2, 1.20.4, 1.20.6, 1.21.1, 1.21.3, 1.21.4, 1.21.5. Older versions for MC 1.8.9, 1.12.2, and other outdated versions are not supported.
Question: Which mod loaders are supported? Answer: Forge, Fabric, NeoForge. Quilt should also work correctly.
Question: Do I need Fabric API or Quilt Standard Libraries? Answer: Yes, Fabric API is required for Fabric/Quilt. On Quilt, you can install QFAPI/QSL instead. These libraries are not needed for Forge and NeoForge.
Question: I'm using Feather/Lunar Client, and the mod doesn't work properly (button doesn't appear, account list is empty, etc.). When will this be fixed? Answer: These clients break many functions. Since they are closed-source, we cannot add compatibility with them. We recommend contacting the client developers to fix the issues. Many of these clients have built-in account switchers - use those instead.
Question: Can I import/export accounts from/to a file? Can I use access tokens/cookies to add Microsoft accounts? Will this be added? Answer: No. Such behavior is either suspicious or prohibited by Minecraft EULA.
Question: Is this mod open source? Answer: Yes. Distributed under the GNU LGPLv3 license.
Question: I found a bug. Answer: Report it through the Issues system. If you're not sure if it's a bug, you can join the Discord server. If the bug is critical and should not be disclosed publicly, please report it according to the security policy.
Screenshots

Credits
Thanks to the contributors of the minecraft.wiki/Microsoft_authentication page (previously on wiki.vg) for providing useful information about Microsoft authentication.
Thanks to the Methanol developers for providing a convenient HTTP client that we use to automatically upload 30+ files to Modrinth, CurseForge, and GitHub.