Important server.properties Settings Reference
Every server.properties setting the panel exposes: defaults, ranges, which ones are read-only, and which have a live console command.
How to Change These
Use the Settings tab. It edits server.properties through a form, with the ranges and defaults built in. Vanilla, Fabric, Forge and NeoForge share the same 57 settings; Paper shows those plus six more, marked "Paper only" below.
You can also edit server.properties directly from the Files tab. Stop the server first - a running server rewrites the file on shutdown.
Minecraft reads server.properties when it starts. Saving a setting the panel marks restart-required restarts your server for you; anything else is written to the file and takes effect at the next start.
A handful of settings have a live console command that changes the running server as well: /difficulty, /gamemode, /defaultgamemode, /whitelist on|off and /gamerule. Those apply immediately.
The file is plain key=value text, one per line, with # for comments. A missing key means the default.
Server JAR
Server JAR File - a dropdown listing the .jar files in your server directory. It decides which one the server launches. Upload your own through the Files tab or SFTP and it appears here. Restart-required, so saving it restarts the server.
Forge and NeoForge servers whose installer has been run launch from user_jvm_args.txt and the loader's argument file rather than a jar, and the dropdown is only a fallback for them.
Core Gameplay
motd (default "A Minecraft Server") - the line shown in the multiplayer list.
gamemode (default survival) - survival, creative, adventure or spectator. /gamemode and /defaultgamemode change it live.
difficulty (default easy) - peaceful, easy, normal or hard. /difficulty changes it live.
hardcore (default false) - hardcore rules. Restart-required, and it is a world-creation property in practice.
pvp (default true, Paper only) - whether players can damage each other.
allow-flight (default false) - permits flight for non-creative players, which is normally only wanted with a flight plugin or mod.
force-gamemode (default false) - puts every player into the default game mode on join, overriding per-player changes.
spawn-protection (default 16, range 0-256) - blocks around spawn only operators may build in. 0 disables it.
spawn-animals, spawn-monsters, spawn-npcs (all default true, Paper only).
player-idle-timeout (default 0, range 0-1440 minutes) - kick idle players. 0 disables it.
allow-nether (default true, Paper only) - restart-required.
enforce-secure-profile (default true) - restart-required.
hide-online-players (default false), max-chained-neighbor-updates (default 1000000), prevent-proxy-connections (default false).
Performance
view-distance (default 10, range 3-32) - chunk radius sent to clients.
simulation-distance (default 10, range 3-32) - chunk radius that actually ticks. Lowering this saves more CPU than lowering view-distance.
max-players (default 20, range 1-999) - restart-required.
max-tick-time (default 60000, range 0-300000 ms) - how long a tick may run before the watchdog acts.
network-compression-threshold (default 256, range -1 to 65535) - packet size above which packets are compressed. -1 disables.
entity-broadcast-range-percentage (default 100, range 10-1000) - how far entities are sent to clients.
pause-when-empty-seconds (default 0, range 0-3600) - stop ticking a world with nobody in it after this many seconds. 0 disables.
use-native-transport (default true), sync-chunk-writes (default true), rate-limit (default 0), region-file-compression (default deflate).
max-world-size (default 29999984, up to 29999984) - the world border radius in blocks. Restart-required.
Six settings on this page exist on Paper only: pvp, allow-nether, spawn-animals, spawn-monsters, spawn-npcs and enable-command-block. On Vanilla, Fabric, Forge and NeoForge they are not in the Settings form.
Network (mostly read-only)
server-port - your assigned game port. Read-only: GameGrid allocates it and rewrites it on every start. It is not 25565.
server-ip - read-only, left blank so the server binds all interfaces.
query.port - read-only. Query shares the game port on this platform.
rcon.port - read-only. RCON is placed one above your game port and is firewalled to the host, so it is not reachable from the internet.
enable-rcon (default false in the schema) and rcon.password - read-only, both managed by the platform. It enables RCON and sets a password on every start, because the player roster, the live map and shop delivery all use it, and console commands fall back to it when the server console cannot take them. A password your server already has is kept; one is generated only for a server without one. Settings shows the password masked and marked as managed, and it cannot be changed there.
enable-query (default false) - restart-required.
online-mode (default true) - restart-required. Verifies accounts with Mojang. Leave it on unless the server sits behind a proxy that does the verification instead.
enable-status (default true) - answers server-list pings.
World Generation
All of these are restart-required, and all of them only affect a world that does not exist yet.
level-name (default world) - the world folder. Changing it starts a new world in a new folder. On 26.2 every server type, Paper included, keeps all three dimensions inside that one folder, under dimensions/minecraft/ (overworld, the_nether and the_end). The separate world_nether and world_the_end folders of older Paper versions are no longer used.
level-seed (default blank) - blank means a random seed. Only used when the world is first generated.
level-type (default minecraft:normal) - minecraft:normal, minecraft:flat, minecraft:large_biomes, minecraft:amplified, minecraft:single_biome.
generator-settings (default {}) - JSON generation settings, mostly used for flat worlds.
generate-structures (default true) - villages, temples, strongholds and the rest.
Players, Permissions and Packs
white-list (default false) - enable the whitelist. /whitelist on and /whitelist off change it live. The list itself is managed in Settings > Player Management.
enforce-whitelist (default false) - kick players who are no longer whitelisted, rather than waiting until they reconnect.
op-permission-level (default 4, range 1-4) - the level a new operator gets. See OP Permission Levels.
function-permission-level (default 2, range 1-4) - the level datapack functions run at.
enable-command-block (default false, Paper only) - restart-required.
broadcast-console-to-ops (default true) and broadcast-rcon-to-ops (default true in the schema; the platform sets it false at start so panel commands do not appear in operators' chat).
resource-pack, resource-pack-sha1, resource-pack-id, resource-pack-prompt and require-resource-pack (default false) - see Setting Up Resource Packs.
accepts-transfers (default false), log-ips (default true), enable-jmx-monitoring (default false), initial-enabled-packs (default vanilla), initial-disabled-packs (default blank).
chat-spam-threshold-seconds and command-spam-threshold-seconds (both default 10, range 1-300).