SumUp API
SumUp publishes a REST API at developer.sumup.com covering checkouts, transactions, payouts, readers, and merchants, open to any merchant with a developer account. Auth is API keys or OAuth 2.0, with official SDKs in seven languages. Banking surfaces like Business Account stay walled off.
Frequently asked questions
SumUp scores A on the API Report Card. SumUp publishes a REST API at developer.sumup.com covering checkouts, transactions, payouts, readers, and merchants, open to any merchant with a developer account. Auth is API keys or OAuth 2.0, with official SDKs in seven languages. Banking surfaces like Business Account stay walled off.
SumUp has a workable official integration path. Most engineering teams can build against it directly. Open API: self-serve, documented, with SDKs
SumUp is a European-led fintech that started as a mobile card reader for micro-merchants and has expanded into a vertically integrated SMB payments and commerce stack: card readers (Solo, Air, 3G), POS systems (SumUp POS, POS Lite, Self-Service Kiosk), online payments and invoicing, a Business Account with IBAN and a debit card, loyalty (SumUp Connect), gift cards, and a consumer-facing 'SumUp Pay' wallet.
Financial Services (Mobile Card Reader & SMB Payment Processing), Micro and small merchants in retail, food & beverage, personal services, and mobile/field trades who need a sub-$50 card reader, a free POS app, and a place to receive funds. A merchant signs up, gets KYC-verified (24–72h), buys a card reader, and pairs it to the free SumUp app on iOS/Android to take chip, contactless, Apple Pay, and Google Pay payments at the published rate (1.69% UK in-person, 2.6% + 10c US).
4M+ merchants across 37 markets, ~3,000+ employees in 20 offices, dual HQ in London (SumUp Payments Ltd) and Berlin (SumUp Services GmbH). The SumUp Business Account crossed 1.5M active merchants and €1B+ in deposits.
Yes, SumUp sits on the full operating ledger of 4M+ merchants: every card transaction, refund, chargeback, payout, invoice, customer record, item catalog, loyalty membership, and increasingly the Business Account balance, IBAN transfers, debit-card spend, and SumUp Wealth investment positions.
~13 years old, founded 2012 in Dublin/London (current dual HQ London + Berlin).
Rate-limit thresholds are not published, developers only learn limits via 429s in production. Webhook coverage is mostly transaction/checkout events; no first-class events for Business Account ledger movements or payout-status changes documented. Full sourced list under Sources below.
Common alternatives include Square (Block), Zettle by PayPal, Stripe, myPOS, Worldpay (FIS), Adyen. Graded alternatives appear under "More from the report card" below.
Grades measure one thing: can a customer's engineering team get their own data out programmatically? We check six things (whether a real API exists, how access is gated, data coverage, auth quality, docs and developer experience, and stability) and roll them into a letter grade. Grades get re-verified, and they only move on evidence.