Configuring Factorio Server Settings: JSON & Map-Gen Guide

Factorio: Server Configuration Guide

Factorio dedicated servers are controlled by three primary JSON files. Understanding which file to edit is the first step in mastering your server environment.

Of those three, map-gen-settings.json is the one you cannot revise later without a reset or console commands - ore density, water, cliffs and starting area are fixed the moment the world is generated. To get them right the first time, the Factorio map generator previews and scores several seeds with those knobs exposed in its new Custom mode (per-resource amount, water, trees, cliffs, enemy bases, starting area, peaceful) and hands you the best one as a ready-to-run save.

Common Server Properties

These settings are found in server-settings.json and can be edited without resetting your world.

Setting	Type	Description
name	String	The name shown in the server browser.
game_password	String	Password required to join the game.
max_players	Integer	Limit the number of concurrent connections (0 = unlimited).
autosave_interval	Integer	Minutes between automatic saves.
auto_pause	Boolean	If true, the game pauses when no players are online.
allow_commands	Select	Who can use /c (Options: "true", "false", "admins-only").

The complete shipped server-settings.json, with its defaults

Factorio ships server-settings.example.json as its own template, and it documents 28 keys. This is all of them, in the file's order, with the value the example puts there and the file's own comment where it has one. Copy the example, change what you need, leave the rest.

Key	Type	Shipped value	The file's own note
name	string	"Name of the game as it will appear in the game listing"
description	string	"Description of the game that will appear in the listing"
tags	list	["game", "tags"]
max_players	int	0	Maximum number of players allowed, admins can join even a full server. 0 means unlimited.
visibility	object	{"public": true, "lan": true}	public: Game will be published on the official Factorio matching server. lan: Game will be broadcast on LAN.
username	string	empty
password	string	empty	Your Factorio.com account password, not the join password.
token	string	empty	Authentication token. May be used instead of 'password' above.
game_password	string	empty	This is the one players type to join.
require_user_verification	bool	true	When set to true, the server will only allow clients that have a valid Factorio.com account.
max_upload_in_kilobytes_per_second	int	0	optional, default value is 0. 0 means unlimited.
max_upload_slots	int	5	optional, default value is 5. 0 means unlimited.
minimum_latency_in_ticks	int	0	optional one tick is 16ms in default speed, default value is 0. 0 means no minimum.
max_heartbeats_per_second	int	60	Network tick rate. Maximum rate game updates packets are sent at before bundling them together. Minimum value is 6, maximum value is 240.
ignore_player_limit_for_returning_players	bool	false	Players that played on this map already can join even when the max player limit was reached.
allow_commands	string	admins-only	possible values are, true, false and admins-only
autosave_interval	int	10	Autosave interval in minutes
autosave_slots	int	5	server autosave slots, it is cycled through when the server autosaves.
afk_autokick_interval	int	0	How many minutes until someone is kicked when doing nothing, 0 for never.
auto_pause	bool	true	Whether should the server be paused when no players are present.
auto_pause_when_players_connect	bool	false	Whether should the server be paused when someone is connecting to the server.
only_admins_can_pause_the_game	bool	true
autosave_only_on_server	bool	true	Whether autosaves should be saved only on server or also on all connected clients. Default is true.
non_blocking_saving	bool	false	Highly experimental feature, enable only at your own risk of losing your saves. On UNIX systems, server will fork itself to create an autosave. Autosaving on connected Windows clients will be disabled regardless of autosave_only_on_server option.
minimum_segment_size	int	25
minimum_segment_size_peer_count	int	20
maximum_segment_size	int	100
maximum_segment_size_peer_count	int	10

Two of those defaults cause most of the "is my server broken" questions. allow_commands ships as admins-only, so a normal player's /c is refused on a fresh server that nobody has locked down. And only_admins_can_pause_the_game ships true, so players who cannot pause are looking at a default, not a decision. The live equivalents of 19 of these keys can be changed without a restart through /config set; see console commands for the mapping between the two spellings.

map-settings.json: the nine keys and what ships in them

The example map-settings.json carries nine top-level keys. Most are nested objects, and these are the shipped values that people most often want to change:

• difficulty_settings: {"technology_price_multiplier": 1, "spoil_time_modifier": 1}. The first is the classic marathon knob; the second scales every spoil timer, which is the single most impactful setting for a group that finds Gleba too punishing.
• enemy_evolution: {"enabled": true, "time_factor": 4e-06, "destroy_factor": 0.002, "pollution_factor": 9e-07}. Those three coefficients are applied to different things, one per tick, one per destroyed spawner and one per unit of pollution, so they are not directly comparable, but the shipped spread is worth seeing: destroy_factor is 500 times time_factor and over 2,000 times pollution_factor. Setting enabled to false freezes evolution outright.
• enemy_expansion: enabled by default, with max_expansion_distance 7, settler_group_min_size 5, settler_group_max_size 20, and a cooldown between min_expansion_cooldown 14400 and max_expansion_cooldown 216000 ticks, which at 60 ticks a second is 4 minutes to 1 hour.
• asteroids: {"spawning_rate": 1, "max_ray_portals_expanded_per_tick": 100}, the Space Age platform-danger dial.
• max_failed_behavior_count: 3.

The remaining keys in the example are pollution, steering, unit_group and path_finder, all nested objects of tuning coefficients that are best left alone unless you are chasing a specific pathfinding problem.

map-gen-settings.json and the nine presets

The map-gen example is short, and most of it is one key. Its top-level entries are seed (null for random, or a number), width and height (both 0, meaning infinite), starting_area (1, a multiplier the file describes as the "biter free zone radius"), starting_points ([{"x": 0, "y": 0}]), peaceful_mode (false), cliff_settings, property_expression_names and autoplace_controls.

autoplace_controls is the one that matters, and the trap is that the control names are not always the resource names. On Nauvis the build defines twelve of them: coal, copper-ore, iron-ore, stone, uranium-ore, crude-oil, trees, water, rocks, enemy-base, nauvis_cliff and starting_area_moisture. Each takes frequency, size and richness, all shipped at 1. Note the mixed punctuation, hyphens on the ores and underscores on nauvis_cliff and starting_area_moisture; getting that wrong is the usual reason a hand-written map-gen file quietly generates a default world.

The build also ships nine named generation presets you can select instead of hand-writing any of this: default, rich-resources, marathon, death-world, death-world-marathon, rail-world, ribbon-world, lakes and island. The same nine exist with and without Space Age loaded, and the command line takes one by name with --preset.

If you are on a Space Age save, the other four planets define their own controls: Vulcanus has calcite, tungsten_ore, vulcanus_coal, sulfuric_acid_geyser and vulcanus_volcanism; Fulgora has scrap, fulgora_islands and fulgora_cliff; Gleba has gleba_plants, gleba_stone, gleba_water, gleba_cliff and gleba_enemy_base; and Aquilo has aquilo_crude_oil, fluorine_vent and lithium_brine.

Updating Map Rules Mid-Game

If you need to change settings that usually require a world reset (like disabling pollution or slowing down biter evolution), you must use Console Commands. Be aware that these typically disable Steam achievements.

/c game.map_settings.enemy_evolution.time_factor = 0
/c game.map_settings.pollution.enabled = false

Auto-Pause & UPS Efficiency

For large factories, we highly recommend keeping auto_pause enabled. This prevents the simulation from running while the server is empty, ensuring that biters don't evolve and your resources aren't consumed while nobody is there to defend the base.

Fine-tune your factory. View plans.