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# Feature flags API

There are two APIs for feature flags, and they answer different questions. The [`/flags` endpoint](/docs/api/flags.md) evaluates flags for a user at runtime – it's what the SDKs call under the hood, and it's what you use if there's no SDK for your platform. The [feature flags API](/docs/api/feature-flags.md) manages the flag definitions themselves: create, list, update, and delete flags from your own tooling or CI.

Use the API when you want flags in a place PostHog doesn't ship an SDK for, or when flag management should be part of a pipeline rather than a person clicking through the app.

## Before you start

1.  **Set up Feature Flags** – [install a PostHog SDK](/docs/feature-flags/installation.md) so your app can evaluate flags.
2.  **Get API access** – [create a personal API key](/docs/api/personal-api-keys.md) with the scopes you need.

## What you can do here

**Evaluate flags** with [`/flags`](/docs/api/flags.md), using your public project API key and a `distinct_id`. It returns each flag's value for that user, plus any payloads. See the [API installation guide](/docs/feature-flags/installation/api.md) for the request shape.

**Manage flag definitions** with the [feature flags API](/docs/api/feature-flags.md), using a [personal API key](/docs/api/personal-api-keys.md) scoped to `feature_flag:read` or `feature_flag:write`. This covers creating and updating flags, release conditions, variants, and [scheduled changes](/docs/feature-flags/scheduled-flag-changes.md).

**Check impact before you roll out** – the same endpoints back the blast radius, evaluation reasons, and flag status checks you see in the web app, so CI can gate a rollout on them.

For high-volume server-side evaluation, don't call `/flags` per request. Use [local evaluation](/docs/feature-flags/local-evaluation.md) instead: your server pulls the flag definitions once and resolves values in-process.

## Related

-   Create and roll out flags in the [web app](/docs/feature-flags/surfaces/web-app.md).
-   Do the same thing conversationally over [MCP](/docs/feature-flags/surfaces/mcp.md).
-   Read the full [PostHog API reference](/docs/api.md).

### Still have questions?

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