How Multiplicity handles your data.

Account and sign-in

• Email address to identify your account, reopen your saved Canon, send your sign-in code or recovery link, and send product emails only if you have opted in.
• Name or display name if you provide one while generating.
• Sign-in security data so we can keep your account secure: one-time sign-in codes, and, if you choose to add one, a passkey. For a passkey we store only its credential identifier and public key, never your fingerprint, face or device passcode, which stay on your device.
• Session records for the devices you stay signed in on. We store a hashed session token and a hashed record of the browser or app, not the raw values, and you can sign out to revoke a session.

Connected music services and listening history

You choose which sources to connect. Depending on the source, this can include:

• Last.fm: your Last.fm username and your scrobbles with their timestamps, used to build and update your surfaces.
• Apple Music: the library or play-history file you export and upload, used to score albums and build your Canon.
• Spotify: where you connect it, your Spotify account email, profile, saved library and top items (Spotify connection is currently limited to invited testing).
• Google or Apple sign-in: the basic identifier and email those services return when you use them to sign in.

You decide what to connect or upload. Connecting a source and uploading a file are optional actions you take deliberately.

What Multiplicity creates from your listening

From the history you connect, Multiplicity generates and stores your Canon, Rotation, Ledger, Records, Rankings, identity and profile surfaces, along with weekly and monthly history snapshots, so you can reopen and compare them over time.

Plan and billing

If you take a paid plan, we store your plan or tier and the identifiers needed to manage it, including a Stripe customer reference, checkout records and subscription status. Payments are processed by Stripe; we do not store your full card details, and billing data is not your listening history.

Purchases and plan changes happen on the multiplicity.fm website. No purchase can be made inside the Multiplicity apps.

Analytics and diagnostics

• Product analytics such as pages visited, referral details and campaign attribution, tied to a salted, hashed visitor identifier rather than your raw IP address.
• Diagnostics if you report a problem or an error occurs: details such as your browser or app user-agent, language, screen size, the page and your account and plan context, so we can fix faults.

We use your IP address in the moment to derive the hashed visitor identifier and to rate-limit sign-in attempts; we do not store it as a standalone record.

How we use it

• To generate, save and let you revisit your Canon, Rotation, Ledger, Records and identity surfaces.
• To remember your account, keep you signed in securely, and apply the limits and features of your plan.
• To store history snapshots so comparison and history features work over time.
• To understand traffic, diagnose faults and improve the product.
• To send product emails only if you have explicitly agreed to receive them.

Generating editorial with AI

To write the editorial and identity text on your Canon and Rotation, Multiplicity sends the relevant listening-derived details, such as album and artist names and the patterns drawn from your history, to our AI provider, Anthropic, which processes them to generate that text. We do not send your email address, billing details or raw account data for this, and we do not use it for advertising.

Service providers we share data with

We do not sell your personal data. We share it only with the providers that run the service, who process it on our behalf under their own terms:

• Railway hosts the application and stores your data.
• Klaviyo sends our account and product emails, including your sign-in code and recovery emails, and holds the related contact and engagement data.
• Anthropic processes the listening-derived prompts described above to generate editorial and identity text.
• Stripe processes payments and holds your billing details.
• Last.fm, Spotify, Google and Apple are the sources you connect; we exchange data with them only for connections you choose to make.
• Deezer and the Apple iTunes Search service are queried by album and artist name to fetch artwork; we do not send them your personal data.

Some of these providers operate outside the United Kingdom, so your data may be processed internationally under the safeguards set out in their own terms.

The Multiplicity apps

The iOS and Android apps load the Multiplicity service inside a native frame. They behave the same as the website for data, with two clarifications: no purchase can be initiated inside the apps, and plan changes are made on multiplicity.fm. The apps do not stream or play music; they read the history you connect and reflect it back as your surfaces.

Storage and retention

Your uploads, generated surfaces, history snapshots, account and plan data are stored in the application backend on our hosting so you can reopen them. They are kept while your account is active. Data held by our providers, such as Klaviyo and Stripe, is retained or removed according to their own terms.

Your choices and deletion

• Delete your account: you can request deletion from within the product at /account/delete (under You and Profile). We record the request and complete the removal of your stored account and listening data within 30 days. Signing out alone does not delete your data.
• Marketing: you can opt out of product emails at any time using the unsubscribe link or by contacting us.
• Access or removal: you can ask us about, export or remove your stored data by contacting us, and we will also ask our providers to remove it where applicable.

What we don’t do

• We do not sell your personal data.
• We do not make your Canon public by default.
• We do not claim affiliation with Apple Music, Spotify or Last.fm.

Contact

If you want to ask about, export or remove your stored data, contact hello@multiplicity.fm.