NIP-88 ====== Recurring Subscriptions ----------------------- `draft` `optional` This NIP defines a way for a pubkey to create recurring subscription payments to another pubkey. Actors in this flow: * Recipient: A pubkey that receives recurring payments * Subscriber: A pubkey that sends recurring payments * Payment verifier: An optional pubkey recipients can designate to verify payments on their behalf # Kinds `kind:37001` - Tier Event -- Optionally published by recipients `kind:7001` - Subscribe Event -- Published by subscribers `kind:7002` - Unsubscribe Event -- Published by subscribers `kind:7003` - Subscription Payment Receipt -- Published by payment-verifier-pubkey ## `kind:37001`: Tier Event A pubkey that wants to provide others the ability to subscribe to them can create "tiers". These tiers might provide certain benefits to the supporters who subscribe to these. ```js { "kind": 37001, "content": "", "tags": [ [ "title", "..." ], [ "image", "..." ], // Perks [ "perk", "" ], [ "perk", "" ], // Amount possibilities [ "amount", "", "currency", "" ], [ "amount", "", "currency", "" ], // Zap-splits [ "zap", "", "relay-url", "19" ], // 95% [ "zap", "", "relay-url", "1" ], // 5% // Relay and payment-verification [ "r", "wss://my-subscribers-only-relay.com" ], [ "p", "" ], // A unique identifier [ "d", "" ], ] } ``` `.content`: description of what subscribers can expect. Tag `title` is an optional title for the tier. Tag `image` is an optional image for the tier. Zero or more `perk` tags specify the benefits of the tier; these can be rendered as a list of benefits to the user in addition to the content. One or more `amount` tags specify the payment required for this tier and its cadence. * The first argument should be the stringified amount in cents or msats, and the second argument the currency * The third argument SHOULD be one of `daily`, `monthly`, `yearly` One or more `amount` tags MUST exist. Zero or more `zap` tags can exist as defined in NIP-57. A `zap` tag with no pubkey indicates that the client can include any pubkey in the `kind:7001` event (and in the resulting recurring zaps). This way, users can offer a "referral" fee to other clients. An `r` tag can be included to specify a relay where clients can find special content for this tier. Zero or more `p` tags can be included to specify a pubkey that is trusted by the tier creator to verify payments on their behalf. #### Examples * `[ "amount", "100", "usd", "daily" ]`, $1.00 a day. * `[ "amount", "1000000", "msats", "daily" ]`, 1000000 millisats a day. ## Subscribe Event ```js { "kind": 7001, "content": "", "tags": [ [ "p", "" ], [ "e", "" ], [ "event", "" ], [ "amount", "", "", "" ], // Zap-splits [ "zap", "", "19" ], // 95% [ "zap", "fa984bd7dbb282f07e16e7ae87b26a2a7b9b90b7246a44771f0cf5ae58018f52", "1" ], // 5% to client developer where subscription was created ] } ``` When a user wants to subscribe to support a user they create a `kind:7001` event. * `.content` is an optional message the supporter can write. * The `p` tag MUST tag the pubkey being supported. * The `e` tag is optional; it should point to a `kind:37001` support tier event. There MUST be exactly 0 or 1 `e` tag. * The `event` tag is optional; subscribers can opt to keep the version of the event they subscribed to. There MUST be exactly 0 or 1 `event` tag. * The `amount` tag specifies what the supporters is committing to pay to the supported pubkey and the cadence. MUST be equal to one of the amounts specified in the `kind:37001` event if one is tagged. There MUST be exactly 1 `amount` tag. The `kind:7001` event can be created without an `e` tag so that users can create recurring support events without the pubkey receiving the support having explicitly created a support tier. ### Zap splits `kind:7001` events can include zap splits as defined in NIP-57. Zap splits MUST be copied by clients as they exist in the `kind:37001` event being subscribed to. When an event has a `zap` tag with no pubkey, clients can discard it, or add the client developer's pubkey, or any other user they wish to receive a share of recurring subscriptions. ## Paying The supporting user should create a zap `p`-tagging the receiver and e-tagging the `kind:7001`. There MUST be a single `p` and a single `e` tag in the zap request. ```js { "kind": 9734, "content": "", "tags": [ [ "p", "" ], [ "e", "" ] ] } ``` Clients supporting this NIP can check for zaps e-tagging the `kind:7001` event to find the pubkeys that have a valid, paid subscriptions at each different period. The same `kind:7001` is re-zapped on a regular basis per the cadence specified in the event. ## Stopping a subscription A user who wants to signal they are no longer subscribed can publish a `kind:7002` event tagging the `kind:7001` they are stopping and `p`-tagging the pubkey they are no longer subscribed to. ```js { "kind": 7002, "content": "", "tags": [ [ "p", "" ], [ "e", "" ], ] } ``` ## Subscription Payment Receipt When a subscription payment is made and a `payment-verifier-pubkey` is set on the `kind:37001` this pubkey publishes `kind:7003` events tagging the `kind:7001` event that was paid and `p`-tagging the pubkey that received the payment. ```js { "kind": 7003, "content": "", "tags": [ [ "p", "" ], [ "P", "" ], [ "e", "" ], [ "valid", "", "" ] [ "tier", "kind:37001-d-tag" ] ] } ``` `p` is the pubkey that received the payment. `P` is the pubkey that made the payment. `e` is the `kind:7001` event that was paid. `valid` is the period for which the payment is valid. `tier` is the d-tag of the `kind:37001` that this subscription is for. # Appendix 0: Verifying Payment The following conditions must be met to verify a payment: * Time between zap receipts should be equal or less than the cadence specified in the `kind:7001` event. * Amount of the zap receipt should be equal or greater than the amount specified in the `kind:7001` event. For currencies not directly supported by the zap spec, clients should do a best effort conversion to the currency specified in the `kind:7001` event at the time of zap receipt. * Zap-receipts should include a zap request `e`-tagging the `kind:7001` event. Zap-receipts might not include a signature (for NWC-automated payments where the subscriber is not present to sign the zap request). * Validations specified in [NIP-57](https://github.com/nostr-protocol/nips/blob/master/57.md). If `kind:7003` events are published by the payment-verifier-pubkey, clients can use these to verify payments more simply.