The short version What we built: ELN Billing , a platform that consolidates billing for multiple in-house SaaS products into one place. It wraps Stripe and handles subscriptions, coupons, one-time charges, referral rewards, and refunds through a single API family. When a payment or cancellation happens, it notifies each service through signed webhooks (automated server-to-server notifications). Why we built it: payment code is heavy. One existing site alone had more than 30 files relate...