Sample guide: Collect a subscription or one-time payment

Collecting crypto subscriptions on-chain can be done in 4 simple steps.

  1. Create an item

  2. Collect authorization via checkout page or widget

  3. Invoice (i.e. schedule payment) by creating a transfer request

  4. Configuring webhooks and granting access

  5. Handling cancellations

Using our SDK

1. Create a subscription

You can use our create POST items endpoint to configure subscriptions in Loop. A subscription is denoted with a type = 2 and a one-time payment has a type=2 and a frequencyCount = 0.

These items will appear on the company dashboard and can also be managed there.

2. Collecting authorization

Companies have two ways to collect authorization: use Loop's checkout page or add Loop’s checkout widget to your website.

Checkout page

Loop provides a custom checkout page for each item with the type of "subscription, donation, and fee". This page can be sent directly to the end customer via email, telegram, or an externally generated invoice or it can be embedded directly on your site in a "pay with crypto" button.

Checkout widget

For those that prefer, Loop provides checkout widget that can be integrated in the context of your company's website or application, to enable your customers to pay with crypto. The modal allows end users to give Loop authorization to enable autopay.

3. Invoice

Once you have authorization to bill a customer, you can then schedule payments. You can choose to auto-invoice or bill manually.


This is best for companies that have fixed payment amounts and dates (i.e. $30/mo every month).

Loop will automatically generate the next invoice for subscriptions and one-time payments with auto-invoicing enabled based on the item's payment frequency and amount specified.


This is best for companies who may have changing payment amounts and dates and thus require flexibility in scheduling payments or are using Loop to schedule outbound payments.

Companies can generate an invoice (called a transfer requests) manually using the POST Transfers call.

4. Configuring webhooks and granting access

Loop uses webhooks to notify you of events. You can configure these webhooks by simply providing an endpoint.

The AgreementSignedUp event lets you know that a wallet provided authorization to be billed - it does not mean you have been paid yet, but it does indicate the user has set an allowance for payments.

The TransferProcessed event is the payment notification and indicates funds have been sent to the receiving wallet.

The AgreementCancelled event is the notification that indicates a customer has cancelled their subscription. See below for more details on cancellations.

Granting access

You can use the wallet address, email, or a reference ID provided in either of these events to provide access to your system.

Even with immediate invoicing, there will be a delay between the webhook events, as the transaction must be confirmed on-chain. Companies can decide to grant access based on the AgreementSignedUp event and take action if you do not hear about the TransferProcessed event within a certain amount of time, (e.g. show a warning, etc). We built Loop to be flexible, so companies can decide how "aggressive" they want to be about payment confirmation.

There are a few reasons why the TransferProcessed event would not occur:

  • The wallet does not have enough balance to cover the payment

  • The wallet does not have enough token allowance to cover the payment

  • The transaction is stuck in the mempool

  • Loop's relay network is down

Wallet amount and balance information can be found on our company dashboard for all active subscribers if you are troubleshooting a late payment.

5. Cancellations

Customers can cancel a subscription either:

  1. directly with the end company, who then can tell Loop about the cancellation via the PATCH agreements call, or

  2. the customer can cancel directly on Loop's Portal.

Regardless of method, Loop will emit a AgreementCancelled events that can be used to manage the end customer's access.

When a subscription is canceled, all future scheduled invoices will be cancelled but any currently due invoices will not be. Companies can cancel these scheduled payments using the PATCH Transfer call.

Last updated