CLI Arguments

The server accepts arguments when launched via java -jar HytaleServer.jar [options].

java -jar HytaleServer.jar --bind 5520 --assets ../HytaleAssets

General

Flag	Type	Description
--help	flag	Prints help and exits
--version	flag	Prints version, patchline, and environment info, then exits
--bare	flag	Skips worlds, networking, and directory creation. All mods still load.

Bare mode

--bare disables core server side effects:

• No worlds are loaded or created
• No network port binding
• No directory creation (player data, resource storage, mods/ folder)

The server still runs the full mod lifecycle up through setup(). When combined with --shutdown-after-validate, the server exits before start() — so mods only go through the preLoad and setup phases.

Caution

All mods still load in bare mode — the flag only affects core server behavior. If mods present in the mods/ directory perform side effects during setup() (database connections, file writes, etc.), that code will still run. The mods/ directory won’t be auto-created if missing, but any mods already present load normally.

Networking

Flag	Type	Default	Description
-b, --bind	host:port	0.0.0.0:5520	Address to listen on
-t, --transport	enum	QUIC	Network transport type: QUIC or TCP
--force-network-flush	true/false	true	Forces network flush each tick

The --bind flag accepts multiple formats:

• --bind 0.0.0.0:5520 — full address
• --bind 5520 — port only, binds all interfaces
• --bind myhost.example.com — hostname only, uses port 5520
• --bind 0.0.0.0:5520,0.0.0.0:5521 — multiple addresses (comma-separated)

Authentication

Flag	Type	Default	Description
--auth-mode	enum	authenticated	authenticated, offline, or insecure. See Authentication Modes for details.
--session-token	string		Session token for the Session Service API
--identity-token	string		Identity token (JWT)

Assets & Mods

Flag	Type	Default	Description
--assets	path	../HytaleAssets	Asset directory or zip file
--mods	paths		Additional mod directories (comma-separated)
--early-plugins	paths		Early plugin directories (comma-separated, requires --accept-early-plugins)
--accept-early-plugins	flag		Acknowledges that early plugins are unsupported and may cause instability
--disable-asset-compare	flag		Disables asset comparison
--disable-file-watcher	flag		Disables hot-reload file watching

Validation & Schema

Flag	Type	Description
--validate-assets	flag	Exit with error if any assets are invalid
--validate-prefabs	options	Exit with error if any prefabs are invalid. Optional validation options: PHYSICS, BLOCKS, BLOCK_STATES, ENTITIES, BLOCK_FILLER (comma-separated).
--validate-world-gen	flag	Exit with error if default world gen config is invalid
--shutdown-after-validate	flag	Shut down after validation completes. Also sets log level to WARNING.
--generate-schema	flag	Generate JSON schemas into the assets directory, then exit

These flags are designed for CI pipelines and tooling:

# validate assets in CI
java -jar HytaleServer.jar \
  --bare \
  --validate-assets \
  --shutdown-after-validate \
  --disable-sentry \
  --auth-mode offline

World & Universe

Flag	Type	Description
--universe	path	Universe directory (where worlds are stored)
--world-gen	path	World generation config directory

Prefabs

Flag	Type	Description
--disable-cpb-build	flag	Disables building compact prefab buffers
--prefab-cache	path	Prefab cache directory for immutable assets

Backup

Flag	Type	Default	Description
--backup	flag		Enables periodic backups
--backup-dir	path		Backup directory (required if --backup is set)
--backup-frequency	integer	30	Backup interval in minutes
--backup-max-count	integer	5	Maximum number of backups to keep

Singleplayer / Owner

Flag	Type	Description
--singleplayer	flag	Runs in singleplayer mode
--owner-name	string	Owner player name
--owner-uuid	UUID	Owner player UUID
--client-pid	integer	Client process ID (used to monitor the client process)

Migrations

Flag	Type	Description
--migrations	name=path	Migrations to run (comma-separated name=/path pairs)
--migrate-worlds	strings	Worlds to migrate (comma-separated, only available when --migrations is set)

Logging & Debug

Flag	Type	Description
--log	levels	Set logger levels. --log WARNING for global, or --log com.foo:FINE,com.bar:WARNING per-package. Uses java.util.logging.Level names.
--boot-command	strings	Commands to run on boot (comma-separated, executed synchronously in order)
--allow-op	flag	Allows the self-op command
--event-debug	flag	Enables event debug logging
--disable-sentry	flag	Disables Sentry error reporting