Payments & Billing APIs shortlist: Under $10k/mo + E-commerce / retail

Narrow your payment processor shortlist based on the constraints that actually matter at your stage—not the feature checklist. A Stripe-first startup building in the US has different requirements than a marketplace collecting from 40 countries or a SaaS business that needs a merchant of record to handle tax compliance. Processing fee structures vary by volume, card type, and geography in ways that can make one provider 30-40% more expensive than another at scale. Use these filters to get to a realistic shortlist of two or three candidates.