---
title: "Evaluates a feature flag for the given context."
method: POST
path: "/v1/sdk/evaluate"
tags: ["Server SDK"]
---

# Evaluates a feature flag for the given context.

`POST /v1/sdk/evaluate`

## Request

- Base URL: `https://eval.featureflip.io`
- URL: `https://eval.featureflip.io/v1/sdk/evaluate`
- Auth: API key in header `Authorization`

## Request body

- EvaluateFlagRequest
  - `flagKey` string, nullable, required
  - `context` EvaluationContextDto, required
    - `userId` string, nullable
    - `attributes` object, nullable

## Response `200`

Returns the evaluation result.

- EvaluateFlagResponse
  - `key` string, nullable, required
  - `variation` string, nullable, required
  - `value` unknown, required
  - `reason` string, nullable, required
  - `prerequisiteKey` string, nullable

## Other responses

- `401`: SDK key is missing or invalid.
- `404`: Flag with the specified key was not found.
- `503`: Service Unavailable

---

[API](https://skmtc.dev/featureflip/apis/featureflip-evaluation-api.md) · [All operations](https://skmtc.dev/featureflip/apis/featureflip-evaluation-api/llms.txt) · [OpenAPI document](https://skmtc.dev/featureflip/apis/featureflip-evaluation-api/revisions/1f5311d7fc25?raw)