A basic Node.js script for copying customer subscriptions from one Stripe account to another after a data migration.

migrate-stripe-subscriptions.ts

import readline from 'readline'

import Stripe from 'stripe'

if (!process.env.STRIPE_SK || !process.env.STRIPE_OLD_SK) {
  throw new Error('Must set STRIPE_SK and STRIPE_OLD_SK environment variables!')
}

const apiVersion = '2022-11-15'
export const stripeNew = new Stripe(process.env.STRIPE_SK, { apiVersion })
export const stripeOld = new Stripe(process.env.STRIPE_OLD_SK, { apiVersion })

void (async () => {
  let customers: Stripe.Response<Stripe.ApiList<Stripe.Customer>> | null =
    await stripeNew.customers.list()

  while (customers?.data.length) {
    for (const customer of customers.data) {
      const subscriptions = await stripeNew.subscriptions.list({
        customer: customer.id,
      })

      if (subscriptions.data.length > 0) {
        console.warn(
          `✋ Customer ${
            customer.email ?? customer.id
          } already has a subscription. Skipped.`,
        )
        continue
      }

      try {
        // Stripe maintains customer IDs when copying from accounts, so we can
        // use that to fetch the customer data from the original Stripe account
        const oldCustomer = await stripeOld.customers.retrieve(customer.id)

        if (oldCustomer.deleted) {
          console.warn(`✋ Customer ${customer.id} is deleted. Skipped.`)
          continue
        }

        const oldSubscriptions = await stripeOld.subscriptions.list({
          customer: oldCustomer.id,
        })

        const [subscriptionToCopy] = oldSubscriptions.data
        if (!subscriptionToCopy || oldSubscriptions.data.length > 1) {
          // not expecting more than 1 subscription, but just in case...
          console.warn(
            `✋ Customer ${oldCustomer.email ?? oldCustomer.id} has ${
              oldSubscriptions.data.length
            } subscriptions. Skipped.`,
          )
          continue
        }

        const subscriptionItems = subscriptionToCopy.items.data
        if (subscriptionItems.length > 1) {
          // not expecting more than 1 subscription item, but just in case...
          console.warn(
            `✋ Subscription ${subscriptionToCopy?.id} has ${subscriptionItems.length} items. Skipped.`,
          )
          continue
        }

        const [subscriptionItem] = subscriptionItems
        if (!subscriptionItem) {
          console.warn(
            `✋ Subscription ${subscriptionToCopy.id} has 0 items. Skipped.`,
          )
          continue
        }

        const coupon = subscriptionToCopy.latest_invoice
          ? await getInvoiceCoupon(subscriptionToCopy.latest_invoice, 'old')
          : undefined

        const newSubscriptionCopy: Stripe.SubscriptionCreateParams = {
          customer: customer.id,
          metadata: { oldSubscriptionId: subscriptionToCopy.id },
          cancel_at_period_end: subscriptionToCopy.cancel_at_period_end,
          backdate_start_date: subscriptionToCopy.start_date,
          trial_end: subscriptionToCopy.current_period_end,
          items: [{ price: subscriptionItem.price.id }],
          automatic_tax: subscriptionToCopy.automatic_tax,
          coupon: coupon?.id,
        }

        const confirmed = await confirmContinue(
          newSubscriptionCopy,
          customer.email ?? customer.id,
        )

        if (confirmed) {
          console.log('🤑 Creating subscription...')
          const newSubscription = await stripeNew.subscriptions.create(
            newSubscriptionCopy,
          )

          await stripeOld.subscriptions.update(subscriptionToCopy.id, {
            // pause collecting payments for the old subscription
            pause_collection: { behavior: 'void' },
            // migratedSubscriptionId as metadata will come handy.
            // I use it to check if an update notification is for a subscription
            // that's already been migrateed, in which case I can ignore it.
            // That's important here because pausing itself triggers an update!
            metadata: { migratedSubscriptionId: newSubscription.id },
          })

          // At the time of building this, Stripe didn't seem to correctly copy
          // the customer's locale, so let's just do that here too...
          await stripeNew.customers.update(customer.id, {
            preferred_locales: oldCustomer.preferred_locales ?? undefined,
          })

          console.log(
            `✅ Created subscription for ${customer.email ?? customer.id}\n`,
          )
        } else {
          console.log('↩️ Skipped.')
          continue
        }
      } catch (error) {
        const isNewCustomerOnly =
          error instanceof Error && error.message.includes('No such customer')

        if (isNewCustomerOnly) continue
        else throw error
      }
    }

    customers = customers.has_more
      ? await stripeNew.customers.list({
          starting_after: customers.data.pop()?.id,
        })
      : null
  }
})()

async function getInvoiceCoupon(
  invoice: Stripe.Invoice | string,
  env: 'old' | 'new',
) {
  const stripe = env === 'old' ? stripeOld : stripeNew

  const theInvoice =
    typeof invoice === 'string'
      ? await stripe.invoices.retrieve(invoice)
      : invoice

  return theInvoice?.discount?.coupon
}

function timeString(timestamp: number | 'now') {
  return timestamp === 'now'
    ? Date.now().toString()
    : // eslint-disable-next-line skyscanner-dates/no-new-date-with-args
      new Date(timestamp * 1000).toString()
}

async function confirmContinue(
  subscription: Stripe.SubscriptionCreateParams,
  customer: string,
) {
  const { backdate_start_date, trial_end } = subscription

  console.log(`Creating subscription for ${customer}:`, {
    ...subscription,
    backdate_start_date: backdate_start_date && timeString(backdate_start_date),
    trial_end: trial_end && timeString(trial_end),
  })

  const prompt = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  })

  return new Promise(resolve => {
    prompt.question(
      `\n🚦 Enter exactly "y" to sync subscription for ${customer}...  `,
      answer => {
        prompt.close()
        console.log()
        resolve(answer === 'y' || answer === '"y"') // ¯\_(ツ)_/¯
      },
    )
  })
}