Offline Whitelist
This server-side mod is a compact utility solution that provides server owners and administrators with the ability to use the whitelist system on servers running in offline mode.
Although the use of cracked servers or servers in offline mode is not recommended, there are sometimes valid reasons for doing so. It's important to note that players added to the whitelist in offline mode will not be available when switching back to online mode - in this case, you'll need to re-add all participants to the list.
The mod is built on the standard Minecraft whitelist system, so the commands remain similar, except for the prefix: instead of the regular whitelist, olwhitelist is used.