payment service provider (PSP)
A payment service provider (PSP) is a firm that provides payment services to businesses or consumers. In UK law the term covers banks, e-money institutions and payment institutions. In everyday use it means the company a business takes card and online payments through, often combining gateway, acquiring and payouts.
The Payment Services Regulations 2017 use "payment service provider" broadly: banks, building societies, e-money institutions, authorised and small payment institutions and a few others. The industry uses it more narrowly, for the provider a business signs up with to accept payments, especially online. That provider may be an acquirer in its own right, a payment facilitator operating under one, or a gateway reselling someone else's acquiring, and the distinction is not always on the website.
Why it matters to a business: the question is not whether a provider calls itself a PSP but what it holds. Who is the regulated party on the contract? Who holds the money between payment and payout? Who sets the merchant service charge and who can change it? The PSR's card-acquiring review found that most small merchants cannot compare providers on price because the pricing is opaque, so the way through is to ask these questions and write the answers down.
For a software platform, the PSP is usually the incumbent the platform's customers each use today, and therefore what the platform's payment volume is spread across. Mapping which customers are on which PSP, at what rate, with which saved cards and mandates, is the first step of a payments review. Synapto is not the PSP in this sense; the regulated acquiring partner is the authorised provider and Synapto sets up the platform's payments on top of it.