Client
Server
Glossary
The words these docs use, in alphabetical order.
Apple Music API
Apple's REST API for Apple Music, at https://api.music.apple.com. Every request is JSON over HTTPS and carries a developer token. This SDK sends every request there and nowhere else.
Artwork template
What Apple sends instead of an image URL: a URL with {w} and {h} where the pixel size goes. You fill in the size you want. See Show artwork.
Catalog
Everything Apple Music offers in a storefront: songs, albums, artists, playlists, music videos, stations, charts and search. Reading the catalog needs only a developer token. client-catalog covers it.
Client
The object every request goes through, made by createClient in core or by one of the integrations. It holds your tokens and settings. Every function that asks Apple for something takes a client, or is already bound to one.
Developer token
A JSON Web Token (JWT) you sign with your MusicKit private key. It tells Apple a request comes from a registered developer, and every request needs one. See Developer tokens and Music User Tokens.
Intake
The route on your server that takes a Music User Token from a page, checks it with Apple and stores it: userTokenIntake in user-token, which server re-exports. See Keep a listener's token on your server.
Integration
One of the three packages an app installs: server, browser or react. Each gives you a ready-made client and re-exports what an app uses of the other packages. See Which package to install.
ISRC
International Standard Recording Code: a 12-character code that identifies one recording, such as GBAYE0601498. Apple can look songs and music videos up by ISRC, which is how a track from another service is best found in Apple's catalog.
JWT
JSON Web Token: a signed, base64url-encoded string of three parts. A developer token is a JWT signed with the ES256 algorithm.
Key ID
The 10-character ID of your MusicKit private key. It is also the part of the key file's name after AuthKey_.
Library
A listener's own collection in Apple Music: what they have added from the catalog, and the playlists they made. Reading or changing it needs their Music User Token. client-user covers it.
Listener
The person using your app who signs in with their Apple Account. Their Music User Token lets your app read and change their library.
Music User Token
A token Apple issues after a listener signs in, which lets your app act for them. Requests for their library, ratings, recommendations and history (paths under /v1/me), their personal station and a catalog resource's library relationship need it, as well as a developer token. Only Apple can issue one. For your own account, the CLI's login gets one: see The command-line tool. See also Developer tokens and Music User Tokens.
MusicKit on the Web
Apple's JavaScript library for web pages, served from Apple's CDN. The SDK uses it for one thing: signing a listener in. See Sign a listener in.
MusicKit private key
The .p8 file you download from your Apple Developer account, which signs developer tokens. Apple lets you download it once. Keep it out of your repository and out of anything a browser loads. See Set up your MusicKit key.
Namespace
A set of functions on a client under one name: catalog, user or playlists. Each function is bound to the client, so you don't pass it one. Those of catalog and user hand over what Apple's answer holds rather than the whole answer: a song, say, rather than { data: [song] }. See What an integration gives you.
Page, next link
Apple answers a request for a long list one page at a time. Each page holds data, the items, and next, the path of the following page, until the last. A function that walks pages follows next for you.
Preview
A short audio clip of a song, under attributes.previews in the catalog. Any audio element can play it. See Play song previews.
Provider
A function the client calls for a token when it needs one, rather than a fixed token string. The developer token providers in developer-token cache a token and replace it before it expires.
Relationship
A list of resources linked to another resource, such as an album's tracks or a song's artists. It is a page like any other list.
Resource
One object in Apple's API, such as a song or a library playlist. Every resource has an id, a type and an href, and usually attributes and relationships.
Standard Schema
A shared interface for validators, which libraries such as Zod and Valibot implement. core's request and every function of the two clients take one as their schema option. See Validate Apple's responses.
Storefront
The country or region whose Apple Music catalog you ask, as a two-letter code such as us or gb. Each storefront has its own catalog, and an ID in one may not exist in another.
Team ID
The 10-character ID of your Apple Developer team, shown on your membership page.
Token endpoint
A route on your server that hands a page a short-lived developer token. A page cannot sign one itself, because it cannot hold the private key. tokenEndpoint in server is that route. See Serve a developer token to a page.
UPC
Universal Product Code: the barcode number of a release. Apple can look albums up by UPC.
View
Apple's name for a list it puts together about a resource, such as an artist's top-songs or an album's other-versions. Like a relationship, it comes as a page.