--- title: Authentication description: Details about Postworks API Authentication mechanisms --- [Skip to content](https://support.postworks.co.uk/knowledge/authentication#main-content) ![Logo (transparent background, red emblem, red text, tagline NOT included) (PRIVATE).png\]](https://support.postworks.co.uk/hs-fs/hubfs/Logo%20(transparent%20background%2c%20red%20emblem%2c%20red%20text%2c%20tagline%20NOT%20included)%20(PRIVATE).png?height=40&name=Logo%20(transparent%20background%2c%20red%20emblem%2c%20red%20text%2c%20tagline%20NOT%20included)%20(PRIVATE).png) Open main navigation Close main navigation - [Postworks Portal](https://app.postworks.co.uk/dashboard/send) [Postworks Portal](https://app.postworks.co.uk/dashboard/send) Hello. How can we help you? - There are no suggestions because the search field is empty. 1. [Support Centre](https://support.postworks.co.uk/knowledge?hsLang=en) 2. [Postworks API](https://support.postworks.co.uk/knowledge/postworks-api?hsLang=en) 3. [Getting started](https://support.postworks.co.uk/knowledge/postworks-api?hsLang=en#getting-started) # Authentication ## Details about Postworks API Authentication mechanisms Postworks API uses 2 mechanisms for authenticating: - JWT Token - API Key The JWT Token is recommended for workflows that have an interface and ask the user for an username and password, whereas the API Key is recommended for unattended workflows, like an automated document generation system producing letters that get posted to Postworks. ### JWT Token The JSON Web Token is an implementation of the JWT standard ([RFC 7519](https://tools.ietf.org/html/rfc7519)). This standard defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the **HMAC** algorithm) or a public/private key pair using **RSA** or **ECDSA**. Postworks JWT implementation uses the HMAC algorithm. A JWT token is obtained upon calling the `/auth/login` endpoint with a valid username and password. ![JWT Workflow](https://support.postworks.co.uk/hs-fs/hubfs/JWT%20Workflow.png?width=282&height=842&name=JWT%20Workflow.png) You can find more information about the JSON Web Tokens at [jwt.io](https://jwt.io/introduction) including a debugger for reading and debugging JWT content.   ### API Key An API key can be used, instead of a JWT token, allowing for more flexible integrations with our API. The API key should be place inside the header of the request: `X-API-KEY: ` Requests will then be validated and authorized against the key in the Authentication header. Please contact support to request your API Key. 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