How to use the generator
Pick Java Edition or Bedrock Edition first, because the two servers use different keys. Then tap a quick preset, like Survival with friends or Low lag, or change settings one by one.
A small dot marks every setting you changed. Tap the reset arrow next to it to go back to the default, or use the search box and the "Only changed" filter to find things fast.
The file on the right updates as you go. Copy it, download it as server.properties, or copy a link that brings your settings back later. Passwords are never put in links or saved in your browser.
Fix the file you already have
Paste your server.properties or upload it, and every setting fills in. Keys from mods, plugins or old versions are kept in an "Other keys" list, so nothing gets lost.
The reader follows the same rules as the Java server: comments, backslash escapes, \u codes and lines that continue with a backslash all work. If a key appears twice, the last one wins, just like on the server, and we tell you which ones.
Old spellings get cleaned up too. difficulty=2 becomes normal and level-type=flat becomes minecraft:flat, and removed keys like pvp come with a note on what replaced them.
What changed in recent versions
Java 26.3 turns the whitelist on by default, so a fresh server only lets in players you add. Java 26.2 split the spam kick into chat-spam-threshold-seconds and command-spam-threshold-seconds.
Java 1.21.9 moved pvp, allow-nether, enable-command-block and spawn-monsters to game rules, and added the management server keys for remote control apps. Bedrock servers now use NetherNet networking by default, with server-udp-ports for the player ports.
Where the file goes
Put server.properties in the server folder, next to the server .jar (Java) or bedrock_server (Bedrock), and replace the old one. Changes only load when the server starts.
The Java server rewrites the file every time it starts. It adds any missing keys with their defaults and drops your own comments, so do not keep notes in there. That is also why the "Only changes" file is safe to use.
Tips for a smooth server
View distance has the biggest effect on lag. 8 to 12 chunks is plenty for most servers, and a lower simulation distance keeps farms and mobs from eating the CPU.
Keep online mode on and the whitelist on for friends servers. If you turn on RCON, give it a long random password; the generator can make one for you.