Arma Reforger Config.json Validator
Paste or upload your Arma Reforger server config.json to check JSON syntax, required fields, duplicate mods, invalid Workshop IDs, and common server configuration problems.
Validation runs entirely in your browser; your config is never uploaded. The optional Workshop check sends only mod IDs to the API.
What this validator checks
- JSON syntax with the line and column of the first error.
- Structure: the config must be a JSON object, with objects and arrays where the server expects them.
- Network settings:
bindPort,publicPort, and the A2S and RCON ports must be valid port numbers. - Game settings: a
gameobject with ascenarioId, sanemaxPlayers, and correctly typed fields. - Mods:
game.modsmust be an array of objects with stringmodIdvalues; duplicates and malformed IDs are flagged. - Workshop check (optional): resolve each mod ID against Workshop data to confirm it exists and see its current name.
Checks are deliberately conservative: the validator flags what is publicly documented and clearly wrong, and stays quiet about fields it cannot verify, rather than inventing rules.
How to validate config.json
Paste the file, upload it, or load the example, then run validation. Fix syntax errors first because broken JSON prevents structural checks. After the syntax is valid, review field warnings, duplicate mod IDs, and optional Workshop lookup results.
Common Arma Reforger config errors
The config.json troubleshooting guide covers the usual startup failures: trailing commas, wrong quotes from chat apps and word processors, mods placed at the top level instead of inside game, and scenario IDs that do not match any installed content.
To rebuild a broken config from scratch, use the config generator, and manage the mods array in the mod manager.
How duplicate mods are detected
The validator reads game.mods and compares normalized modId values. If the same Workshop ID appears more than once, it reports the duplicate so you can keep one entry and remove the rest.
How mod IDs are resolved
Local checks verify that each modId is shaped like a Workshop ID. Optional Workshop checks send only the mod IDs to the API to look up names and detect missing or unavailable entries.
Privacy and local validation
JSON parsing and server-config checks run in your browser. Your full config file is not uploaded. Local storage is used only when you choose to work with the shared config draft across tools.
Related tools
Need to rebuild your config? Open the Arma Reforger Config Generator. Need Workshop IDs? Use the Arma Reforger Mods Browser. Only editing mods? Use the Arma Reforger Mod Manager.
Frequently asked questions
Is my config uploaded anywhere?
No. Syntax and structure validation runs entirely in your browser. If you choose to check mod IDs against the Workshop, only the mod IDs are sent to the API, never the rest of your config.
What does the validator check?
JSON syntax with line positions, the overall config structure, port ranges, required game fields like scenarioId, and the game.mods array including duplicate or malformed mod IDs. It does not enforce rules that are not publicly documented.
My config is valid but the server still fails to start. Why?
A structurally valid config can still reference a missing scenario, an unavailable mod version, or a port that is already in use. The troubleshooting guide on this site covers the most common startup failures.