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Core Keeper Server Config Generator

Build a working ServerConfig.json for your Core Keeper dedicated server without hand-editing JSON. Pick the world save slot, seed and difficulty mode, force a seasonal event, and set the player cap — then copy a complete, valid file. Core Keeper splits its setup in two: the world keys live in ServerConfig.json, but the password, port and bind IP are command-line only — so there's a launch-command builder below for those. Nothing's faked: where a default differs between sources, we flag it rather than guess.

Updated Jun 2026Built for Core Keeper dedicated server (Steam app 1963720) · verified against the generated config

World & Difficulty

0 / 0 changed

Which world the server loads and how it plays. Difficulty and seed are baked into a world when it's first generated — changing them only affects a new world on that slot, not one that already exists.

The name shown to players in the server list and used for the world save. A fresh server ships as "Core Keeper" — change it so yours isn't one of dozens of identical entries.

Which save slot the server loads (0–29). Leave it at 0 unless you keep several worlds on one server and want to switch between them. Each slot is an independent world.

0 = random seed — the game picks one when it generates the world. Set a specific number to reproduce a known world layout. Only matters at first generation; an existing world already has its seed baked in.

Normal is the standard experience. Hard hits harder. Creative is free-build with everything unlocked. Casual softens the survival pressure. You can't switch a world between Creative and non-Creative after it's made.

⚠ verify

Forces a holiday event on regardless of the date. Off runs no event; Auto follows the real-world calendar. Handy for running an Easter or Halloween server out of season.

Players & Network

0 / 0 changed

The slot count and one network tuning knob. Most servers never touch the network value.

⚠ 8-cap

The config ships at 100, but Core Keeper's real co-op cap is 8 — setting this higher doesn't add usable slots on the current build. Leave it at 100 (the file default) or set it to 8 to reflect reality; either way the playable ceiling is 8.

A network throttle from the generated config — how many packets the server sends per frame. The default of 1 is fine for almost everyone; only raise it if you understand your network and are chasing a specific sync issue.

Launch Command — Port & Password

CLI only

These aren't in ServerConfig.json. Core Keeper's password, port and bind IP are passed on the command line. Set them here and copy the arguments onto your server's start command (or paste them into your host panel's "launch parameters" field).

-batchmode -nographics

Append these to however you start the server (e.g. your start_server.sh/.bat, systemd ExecStart, or a host's "Additional Launch Parameters" box). -batchmode -nographics runs it headless. Setting -port also enables Direct Connect, which crossplay and port-forwarded joins need.

About the Core Keeper Server Config Generator

Core Keeper's dedicated server (Steam app 1963720, Windows and Linux) keeps its world configuration in one file: ServerConfig.json, written automatically the first time the server launches. It holds the world save slot, the world/server name, the seed, the difficulty mode, an optional seasonal-event override, the player cap and a network packet knob. This generator builds the whole file with dropdowns and number fields and hands you valid JSON — no counting braces, no guessing whether a value is a number or a string. The world keys here were verified against the server's own generated ServerConfig.json and cross-checked across dedicated-server host docs.

Config file vs launch command — Core Keeper splits them

This is the part that trips people up. Core Keeper reads two places: the JSON file and command-line arguments, and some settings only work in one of them. worldName, world, worldSeed, worldMode, seasonOverride, maxNumberPlayers and maxNumberPacketsSentPerFrame live in ServerConfig.json. The password, port and bind IP do not — they're passed on the launch command (-password, -port, -ip). Put a password in the JSON and nothing happens; that's the single most common "my password doesn't work" cause. The Launch Command section above builds those arguments for you.

The 8-player reality

The generated config ships maxNumberPlayers at 100, which looks like a 100-player server. It isn't — Core Keeper's co-op session cap is 8 on the current build, and raising the number doesn't add usable slots. We keep 100 as the file default (so a round-trip matches what the server writes) but flag it honestly: plan for up to 8 players.

Difficulty and seed are baked at world creation

worldMode and worldSeed only take effect when a world is first generated on that slot. Point the server at an existing world and changing the mode or seed does nothing — the world already has them locked in. To actually use a new difficulty or seed, generate a fresh world (a new slot, or delete the old save for that slot first). Note too that you can't convert a world between Creative and non-Creative after the fact.

Does this cover every setting?

Yes — every key in the generated ServerConfig.json (the seven world/network keys), plus the command-line-only port, password, bind IP and platform restriction that the file can't hold. Where sources disagree on a default — the seasonal-event numbering, the player cap reality — we mark it with a ⚠ badge rather than hide it. A network "send rate" key floating around some host docs isn't in the server's generated file, so we leave it out rather than emit a key the server might ignore.

Where the config file actually lives

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