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5.0.0 • Public • Published

conf Build Status

Simple config handling for your app or module

All you have to care about is what to persist. This module will handle all the dull details like where and how.

If you need this for Electron, check out electron-store instead.


$ npm install conf


const Conf = require('conf');
const config = new Conf();
config.set('unicorn', '🦄');
//=> '🦄'
// Use dot-notation to access nested properties
config.set('', true);
//=> {bar: true}
//=> undefined

Or create a subclass.


Changes are written to disk atomically, so if the process crashes during a write, it will not corrupt the existing config.


Returns a new instance.


Type: Object


Type: Object

Default values for the config items.

Note: The values in defaults will overwrite the default key in the schema option.


Type: Object

JSON Schema to validate your config data.

Under the hood, the JSON Schema validator ajv is used to validate your config. We use JSON Schema draft-07 and support all validation keywords and formats.

You should define your schema as an object where each key is the name of your data's property and each value is a JSON schema used to validate that property. See more here.


const Conf = require('conf');
const schema = {
    foo: {
        type: 'number',
        maximum: 100,
        minimum: 1,
        default: 50
    bar: {
        type: 'string',
        format: 'url'
const config = new Conf({schema});
//=> 50
config.set('foo', '1');
// [Error: Config schema violation: `foo` should be number]

Note: The default value will be overwritten by the defaults option if set.


Type: string
Default: config

Name of the config file (without extension).

Useful if you need multiple config files for your app or module. For example, different config files between two major versions.


Type: string
Default: The name field in the package.json closest to where conf is imported.

You only need to specify this if you don't have a package.json file in your project.


Type: string
Default: System default user config directory

You most likely don't need this. Please don't use it unless you really have to.

Overrides projectName.

The only use-case I can think of is having the config located in the app directory or on some external storage.


Type: string Buffer TypedArray DataView
Default: undefined

This can be used to secure sensitive data if the encryption key is stored in a secure manner (not plain-text) in the Node.js app. For example, by using node-keytar to store the encryption key securely, or asking the encryption key from the user (a password) and then storing it in a variable.

In addition to security, this could be used for obscurity. If a user looks through the config directory and finds the config file, since it's just a JSON file, they may be tempted to modify it. By providing an encryption key, the file will be obfuscated, which should hopefully deter any users from doing so.

It also has the added bonus of ensuring the config file's integrity. If the file is changed in any way, the decryption will not work, in which case the store will just reset back to its default state.

When specified, the store will be encrypted using the aes-256-cbc encryption algorithm.


Type: string
Default: json

Extension of the config file.

You would usually not need this, but could be useful if you want to interact with a file with a custom file extension that can be associated with your app. These might be simple save/export/preference files that are intended to be shareable or saved outside of the app.


Type: boolean
Default: true

The config is cleared if reading the config file causes a SyntaxError. This is a good default, as the config file is not intended to be hand-edited, so it usually means the config is corrupt and there's nothing the user can do about it anyway. However, if you let the user edit the config file directly, mistakes might happen and it could be more useful to throw an error when the config is invalid instead of clearing. Disabling this option will make it throw a SyntaxError on invalid config instead of clearing.


Type: Function
Default: value => JSON.stringify(value, null, '\t')

Function to serialize the config object to a UTF-8 string when writing the config file.

You would usually not need this, but it could be useful if you want to use a format other than JSON.


Type: Function
Default: JSON.parse

Function to deserialize the config object from a UTF-8 string when reading the config file.

You would usually not need this, but it could be useful if you want to use a format other than JSON.


Type: string
Default: nodejs

You most likely don't need this. Please don't use it unless you really have to.

Suffix appended to projectName during config file creation to avoid name conflicts with native apps.

You can pass an empty string to remove the suffix.

For example, on macOS, the config file will be stored in the ~/Library/Preferences/foo-nodejs directory, where foo is the projectName.


Type: boolean
Default: true

Accessing nested properties by dot notation. For example:

const config = new Conf();
    foo: {
        bar: {
            foobar: '🦄'
//=> '🦄'

Alternatively, you can set this option to false so the whole string would be treated as one key.

const config = new Conf({accessPropertiesByDotNotation: false});
    ``: '🦄'
//=> '🦄'


You can use dot-notation in a key to access nested properties.

The instance is iterable so you can use it directly in a for…of loop.

.set(key, value)

Set an item.

The value must be JSON serializable. Trying to set the type undefined, function, or symbol will result in a TypeError.


Set multiple items at once.

.get(key, [defaultValue])

Get an item or defaultValue if the item does not exist.


Check if an item exists.


Delete an item.


Delete all items.

.onDidChange(key, callback)

callback: (newValue, oldValue) => {}

Watches the given key, calling callback on any changes. When a key is first set oldValue will be undefined, and when a key is deleted newValue will be undefined.


callback: (newValue, oldValue) => {}

Watches the whole config object, calling callback on any changes. oldValue and newValue will be the config object before and after the change, respectively. You must compare oldValue to newValue to find out what changed.


Get the item count.


Get all the config as an object or replace the current config with an object: = {
    hello: 'world'


Get the path to the config file.


How is this different from configstore?

I'm also the author of configstore. While it's pretty good, I did make some mistakes early on that are hard to change at this point. This module is the result of everything I learned from making configstore. Mainly where the config is stored. In configstore, the config is stored in ~/.config (which is mainly a Linux convention) on all systems, while conf stores config in the system default user config directory. The ~/.config directory, it turns out, often have an incorrect permission on macOS and Windows, which has caused a lot of grief for users.

Can I use YAML or another serialization format?

The serialize and deserialize options can be used to customize the format of the config file, as long as the representation is compatible with utf8 encoding.

Example using YAML:

const Conf = require('conf');
const yaml = require('js-yaml');
const config = new Conf({
    fileExtension: 'yaml',
    serialize: yaml.safeDump,
    deserialize: yaml.safeLoad


  • electron-store - Simple data persistence for your Electron app or module
  • cache-conf - Simple cache config handling for your app or module


MIT © Sindre Sorhus


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