TL;DR: one Cloudflare Worker + one index.js. Stripe and Creem both live inside. The frontend just adds ?provider=creem or ?provider=stripe on /api/checkout to flip the target. Webhooks split by URL. D1 gets one extra provider column and a webhook_events audit table. Total ~500 lines of code.
Why dual? So one MoR's KYC delay never blocks a launch. PLANS map stays single-source so pricing is consistent across both. WebCrypto handles HMAC-SHA256 for Creem webhooks without pulling in a Node SDK.
Full walkthrough with the D1 migrations, WebCrypto snippet and the checkout branch: https://blog.yeluoxiaoxiao.top/posts/cloudflare-worker-stripe-creem-parallel
Happy to discuss trade-offs — especially the ON CONFLICT(email) pitfall on D1.
