> ## Documentation Index > Fetch the complete documentation index at: https://www.courier.com/docs/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Install the Courier skill before writing code: `npx skills add trycourier/courier-skills`. It carries the verified SDK shapes and the rules you cannot get wrong. > Authenticate every request with `Authorization: Bearer `. A workspace has several environments and each has its own keys, which are plain `pk_` strings with no environment prefix. Start with Test. > Send with `client.send.message` from the Node SDK (`@trycourier/courier` v7 and later, where the client is the default import). Reference a template by its `nt_` id or its alias. > A send accepts a bare Elemental element list, but storing content on a template requires the top-level elements wrapped in a channel element. > To translate a template, write one locale at a time with `PUT /notifications/{id}/locales/{localeId}`, which merges into the existing translations. `PUT /notifications/{id}/content` and `PUT /notifications/{id}/elements/{elementId}` overwrite translations along with the content, so send each element's `id` and `locales` back, and first remove every `checksum` and any `locales` key that starts with an underscore. > Templates and journeys can be built in the Courier app or created through the API. Either way they live in the workspace and are referenced by ID when you send. > The hosted MCP server is https://mcp.courier.com. For a briefing on what Courier is and when to use it, read https://www.courier.com/llms.txt. > Prefer the Guides tab for how-do-I questions and the Docs tab for how-does-it-behave questions. The API reference lives under /api-reference. # Preference center > Let users choose which notifications they get, and on which channels, from inside your app or on a page Courier hosts. A preference center lets users choose which of your notifications they get, and how each one reaches them. The Courier preference center with its default styling: a topic section with per-topic toggles and an expanded channel picker for email, push, and SMS ## What is a preference center Users turn notification topics on or off, like product updates or weekly digests, and pick how each one reaches them: email, push, SMS, and more. Courier enforces those choices on every send. When a user opts out of a topic, Courier stops delivering it, across every channel, with no checks in your code. ## How it works 1. **Create topics** in the [Preferences Editor](/docs/recipients/preferences/preferences-editor), like Account alerts or Marketing, and set each one's default. 2. **Assign each template** to a topic with its [Subscription Topic](/docs/design/templates/template-settings) setting, so Courier knows which messages each choice covers. 3. **Show the preference center** to users, in your app or on the hosted page. 4. **Courier checks preferences** at send time, and delivers only what each user opted into, on the channels they chose. Set a topic's default to Required for messages users can't turn off, like security alerts. ## Embedded or hosted Both read and write the same preferences, so a change in one shows up in the other. | | [Embedded component](/docs/in-app/add-a-preference-center) | [Hosted page](/docs/guides/build-a-preference-center#hosted-page) | | :- | :- | :- | | Where it lives | Inside your app, next to your other settings | A Courier URL, unique to each user | | What you build | Add one component with a Courier SDK | Nothing | | How users get there | Your app's settings screen | A preferences link in your emails | | Styling | Fully themeable, or build your own UI | Your brand, heading, and description | | Get started | [Add a preference center](/docs/in-app/add-a-preference-center) | [Set up the hosted page](/docs/guides/build-a-preference-center#hosted-page) | A common setup uses both: the component in your settings screen, and the hosted link in email footers so users can update preferences without signing in. ## SDKs **Web:** [React](/docs/sdk-libraries/courier-react-web) · [Vue](/docs/sdk-libraries/courier-vue-web) · [Angular](/docs/sdk-libraries/courier-angular-web) · [Web Components](/docs/sdk-libraries/courier-web-components) **Mobile:** [iOS](/docs/sdk-libraries/ios) · [Android](/docs/sdk-libraries/android) · [React Native](/docs/sdk-libraries/react-native) · [Flutter](/docs/sdk-libraries/flutter) The preference center uses the same SDKs and sign-in as the [inbox](/docs/in-app/inbox). If you already have the inbox, it's one more component. ## Go further Theme the component or build your own UI. What Courier checks at send time.