> ## Documentation Index
> Fetch the complete documentation index at: https://docs.softlaunch.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature flags

> What flags are, the types they support, and the values they return.

A feature flag is a named switch in your code. Instead of hardcoding behavior, you ask Softlaunch what a flag should return for a given user, and change that answer from the dashboard — no redeploy.

## Flag types

Every flag has a type, set when you create it. The type determines the shape of the value the SDK returns.

| Type      | Returns             | Example use                           |
| --------- | ------------------- | ------------------------------------- |
| `boolean` | `true` or `false`   | Gate a feature on or off              |
| `string`  | A text value        | Choose a variant name, theme, or copy |
| `integer` | A whole number      | A limit, count, or threshold          |
| `numeric` | A decimal number    | A rate, multiplier, or price          |
| `json`    | A structured object | A bundle of related settings          |

Each SDK exposes a typed method per flag type, so you read a flag with the same type you defined. If a flag's type doesn't match the method you call, the SDK returns your default value.

## Variations

A **variation** is a value a flag can return. A boolean flag has two variations (`true` and `false`); other types can have as many as you need — for example a `string` flag with `control`, `treatment-a`, and `treatment-b`.

When you evaluate a flag, Softlaunch resolves it to exactly one variation based on the flag's configuration in that environment.

## Default values

Every SDK call requires a **default value**. The SDK returns it when:

* The configuration hasn't loaded yet.
* The flag doesn't exist in that environment.
* The flag's type doesn't match the method you called.

<Note>
  Choose a default that is safe to serve to every user. It's the value your app falls back to whenever Softlaunch can't return a definitive answer.
</Note>

## Enabling and disabling

A flag is enabled or disabled **per environment**. A disabled flag serves its configured off value to everyone, regardless of targeting. This lets you keep the same flag configured differently in Staging and Production.

<Card title="Environments and SDK keys" icon="layer-group" href="/concepts/environments">
  Learn how a flag can behave differently across environments.
</Card>