Configuration

Jan Agent uses a layered configuration system: CLI flags take priority over config files, which take priority over defaults.

Agent config file

Jan Agent reads agent-config.json from the same directory as the binary. This file persists your preferred defaults so you don't have to pass flags every time.


{
  "serve": {
    "port": 6767,
    "n_gpu_layers": -1,
    "ctx_size": 32768,
    "threads": 0,
    "timeout": 120,
    "fit": false,
    "embedding": false,
    "verbose": false,
    "select_quant": false,
    "model_path": null,
    "bin": null,
    "mmproj": null
  }
}

Priority order

For any setting, the value is resolved in this order:

CLI flag — explicitly passed on the command line
Config file — value in agent-config.json
Default — built-in default

Environment variables

Variable	Description
`JAN_APP_NAME`	App name for locating config directory (default: `Jan`)
`HF_TOKEN`	HuggingFace token for downloading gated models
`LLAMA_ARG_*`	Pass-through flags to the LlamaCPP server (e.g. `LLAMA_ARG_HOST=0.0.0.0`)

Data folder resolution

The Jan data folder is located by reading settings.json from your platform's app data directory:

Platform	Config path
macOS	`~/Library/Application Support/Jan/settings.json`
Linux	`~/.config/Jan/settings.json` (or `$XDG_CONFIG_HOME/Jan/`)
Windows	`%APPDATA%\Jan\settings.json`

The data_folder field in settings.json points to the actual data directory. If not set, it defaults to <platform_data_dir>/Jan/data.

This is the same settings.json used by Jan Desktop, so both applications share the same data folder automatically.

LlamaCPP server arguments

Any llama-server command-line flag can be set via environment variables with the LLAMA_ARG_ prefix:


export LLAMA_ARG_HOST=0.0.0.0
export LLAMA_ARG_N_GPU_LAYERS=32
export LLAMA_ARG_CTX_SIZE=8192
export LLAMA_ARG_THREADS=8
jan serve qwen3-4b

These are merged with CLI flags — explicit CLI flags always win.

CLI Reference Development