Configuring Checkout

When building a checkout URL or configuring the paywall, you can customize things. Here are docs on how to achieve this.

Building a Purchase address

If you are using the paywall application, you can skip this section and move to the next one (the paywallConfig object).

All of the purchase URsL start with the following base

After this, you will need to include the following parameters:

  • paywallConfig=... where ... is replaced with the URL-encoded version of a JSON paywallConfig object. The next section will show you how to build this object.

  • redirectUri=... where ... is replaced with the URL-encodded address of a webpage where the user will be redirected when their membership is valid.

These parameters are all separated by the & sign and you can use online tools such as to build the encoded version of the parameters.


This URL will redirect members to this page

The paywallConfig object

The paywallConfig is a JSON object which includes a set of customizations for your experience. It includes the following elements:

  • locks : required object, a list of lock objects (see below).

  • icon: optional string, the URL for a icon to display in the top left corner of the modal.

  • callToAction: optional object, a list of messages shown based on the state of the checkout modal (see below).

  • persistentCheckout: optional boolean: true __if the modal cannot be closed, defaults to false when embedded. When closed, the user will be redirected to the redirect query param when using a purchase address (see above).

  • useDelegatedProvider: optional boolean. To be announced.

  • network: optional integer. defaults to 1. See below.

  • referrer: optional string. The address which will receive UDT tokens (if the transaction is applicable)

  • messageToSign: optional string. If supplied, the user is prompted to sign this message using their wallet. If using a checkout URL, a signature query param is then appended to the redirectUri (see above). If using the embedded paywall, the unlockProtocol.authenticated includes the signature attribute.

  • pessimistic: optional boolean. defaults to false. By default, to reduce friction, we do not require users to wait for the transaction to be mined before offering them to be redirected. By setting this to true, users will need to wait for the transaction to have been mined in order to proceed to the next step.

  • captcha: optional boolean. defaults to false. If set true, the users will be prompted to go through a captcha during the checkout process. This is better used in conjunction with a purchase hook that verifies that captcha is valid.


The locks object is a list of objects indexed by the lock address, where each object can include the following:

  • network: recommended integer. See below.

  • name: optional string. name of the lock to display.

  • recurringPayments: optional number. The number of time a membership should be renewed automatically. This only applies to ERC20 locks. Read more about recurring memberships.`

  • metadataInputs: optional array, a set of input fields as explained there.

Calls to action

The callToAction object lets you customize the messages displayed on the checkout UI. They are all optional strings:

  • default : displayed by default

  • expired : displayed when the user had a membership previously that expired

  • metadata: displayed when the user is prompted for metadata

Network values

(Make sure you use a number and not a string!)

  • 1: mainnet,

  • 4: rinkeby,

  • 100: xdai,

  • 137: polygon.

Full example

    "pessimistic": true,
    "locks": {
        "0x250a0153DfB52B44c560524283A6629C1d347545": {
           "network": 1,
           "name": "Unlock members"
    "icon": "",
    "callToAction": {
        "default": "Please join the Amber membership!"
    "metadataInputs": [
            "name": "Name",
            "type": "text",
            "required": true

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