How to migrate from Stripe to Polar in 2 hours

If you have an indie SaaS selling to Europe, you've probably felt the pull to migrate from Stripe to Polar. The main reason: Polar is a Merchant of Record and takes VAT off your hands. The technical migration isn't as painful as it sounds. If your Stripe integration is well modularized, it's ~2 hours of work. This guide explains how we'd do it in an existing Next.js app. ## Before migrating: what does NOT move - **Active subscriptions**: don't migrate automatically. Polar doesn't import from Stripe. Existing customers stay on Stripe until they renew or change plans. - **Payment history**: not transferred. Leave it on Stripe as archive. - **Saved payment methods**: not either. Polar will ask for the card again. That's why migration works best with a young SaaS (< 100 subscriptions) or with a gradual switch: new customers on Polar, old ones stay on Stripe until churn. ## Step 1: install Polar ```bash bun add @polar-sh/sdk ``` Keep `stripe` for now; you'll remove it at the end. ## Step 2: environment variables Keep Stripe's and add Polar's: ``` POLAR_ACCESS_TOKEN=polar_oat_... POLAR_WEBHOOK_SECRET=whsec_... POLAR_SERVER=production ``` ## Step 3: create products in Polar Dashboard Replicate the products you have in Stripe. Watch out for: - **Prices**: Polar works in cents like Stripe. But if you have VAT-included prices in Stripe, in Polar you put the net price and Polar adds VAT to the end customer. Decide if your visible pricing changes. - **Recurring intervals**: monthly, yearly. Polar supports them. - **One-time products**: also supported, like Stripe. ## Step 4: abstract the payments logic If you already have an abstraction layer like `PaymentService` or `lib/payments/`, you've got this done. If not, now is the time. `src/lib/payments/types.ts`: ```ts export interface PaymentProvider { createCheckout(params: CheckoutParams): Promise<{ url: string }>; cancelSubscription(subscriptionId: string): Promise; verifyWebhook(body: string, signature: string): Promise; } ``` Implement `StripeProvider` and `PolarProvider`. Switch between them with an env var: ```ts const provider = process.env.PAYMENT_PROVIDER === 'polar' ? new PolarProvider() : new StripeProvider(); ``` ## Step 5: new Polar webhook endpoint Stripe and Polar sign webhooks differently. Create a new endpoint, don't modify the Stripe one: `src/app/api/webhooks/polar/route.ts`: ```ts import { polar } from '@/lib/polar/client'; import { db } from '@/lib/db/client'; export async function POST(req: Request) { const body = await req.text(); const signature = req.headers.get('webhook-signature')!; const event = polar.webhooks.verify({ body, signature, secret: process.env.POLAR_WEBHOOK_SECRET!, }); // Reuse the logic from your Stripe webhook, adapted to Polar events switch (event.type) { case 'subscription.created': // create in DB break; case 'subscription.canceled': // mark as canceled break; } return new Response('OK'); } ``` ## Step 6: cohort strategy In your DB, add a `paymentProvider` field to the subscriptions table: ```prisma model Subscription { id String @id userId String paymentProvider String // 'stripe' | 'polar' externalId String // ID in Stripe or Polar status String ... } ``` When a user cancels and re-subscribes, their new subscription goes to Polar. Old ones stay on Stripe until natural churn. ## Step 7: test in sandbox Polar has a separate sandbox. Before touching production: 1. Create a sandbox account + products in sandbox 2. Set `POLAR_SERVER=sandbox` 3. Make a test purchase with card `4242 4242 4242 4242` 4. Verify the webhook arrives and DB updates 5. Verify cancellation When everything works in sandbox → switch to `production`. ## Step 8: shadow deploy Don't announce the migration on day 1. Deploy Polar to production with: - "Pay with Polar" button hidden behind a feature flag - Enable the flag for your test account - Make a real purchase - Verify Polar transfers the money to your bank account - Enable for all new signups ## Common errors **1. Webhook deduplication**: if you replay the same event, make sure your DB doesn't create duplicate subscriptions. Index by `externalId`. **2. VAT in visible pricing**: if Stripe showed "10€ VAT included", in Polar the customer will see "10€ + VAT" because Polar calculates it. Either drop the net price or raise the visible one. Communicate it. **3. Refunds and disputes**: the logic is different. Read Polar's docs before processing your first refund. ## Bottom line Migrating Stripe → Polar is ~2 hours of code if you have the abstraction in place, or ~1 day from scratch. The longest part is testing in sandbox and shadow-deploying. In return: you forget about VAT, about OSS filings, about the accountant arguing what kind of service a SaaS is. If you sell to Europe, it's worth it.