The Society for Worldwide Interbank Financial Telecommunication (SWIFT), legally S.W.I.F.T. SC, is a cooperative established in 1973 in Belgium (French: Société Coopérative) and owned by the banks and other member firms that use its service. SWIFT provides the main messaging network through which international payments are initiated. It also sells software and services to financial institutions, mostly for use on its proprietary "SWIFTNet", and assigns ISO 9362 Business Identifier Codes (BICs), popularly known as "SWIFT codes".

As of 2018, around half of all high-value cross-border payments worldwide used the SWIFT network, and in 2015, SWIFT linked more than 11,000 financial institutions in over 200 countries and territories, who were exchanging an average of over 32 million messages per day (compared to an average of 2.4 million daily messages in 1995).

SWIFT is headquartered in La Hulpe near Brussels. It hosts an annual conference, called Sibos, specifically aimed at the financial services industry.

Before SWIFT's establishment, international financial transactions were communicated over Telex, a public system involving manual writing and reading of messages. The collapse of the Bretton Woods agreement in 1971, the decoupling of the US dollar's convertibility to gold, a period in economic history now known as the "Nixon shock", shifted major currencies to floating exchange rates and increased the volume of cross-border transactions. That in addition to already increasing amounts of international trade made the existing Telex system insufficient.

In this novel period of international trade in a floating exchange rate environment, SWIFT was set up out of fear of what might happen if a single private and fully American entity controlled global financial flows – which before was First National City Bank (FNCB) of New York – later Citibank. In response to FNCB's protocol, FNCB's competitors in the US and Europe pushed an alternative "messaging system that could replace the public providers and speed up the payment process".

SWIFT was founded in Brussels on 3 May 1973. Individuals who played a key role in its creation included bankers Jan Kraa (at AMRO Bank) and François Dentz (at the Banque de l'Union Parisienne) as well as Carl Reuterskiöld and Bessel Kok, who became respectively its first two chairmen and chief executives. It was initially supported by 239 banks in 15 countries. It soon started to establish common standards for financial transactions and a shared data processing system and worldwide communications network designed by Logica and developed by the Burroughs Corporation.

Fundamental operating procedures and rules for liability were established in 1975, and the first message was ceremonially sent by Prince Albert of Belgium on 9 May 1977.

SWIFT's first non-European operations centre was inaugurated by Governor John N. Dalton of Virginia in 1979. In 1989 SWIFT completed a monumental new head office building in La Hulpe, designed by Ricardo Bofill Taller de Arquitectura.

SWIFT's shareholding structure is adjusted every three years in proportion to volumes of activity incurred by the members, ensuring that the most active members get the most voice irrespective of geography; additional rules are aimed at ensuring some geographical diversity within the board of directors. The 25 directors are elected by the shareholders, on three-year terms with the renewal of one-third of the board every year; all directors are member representatives.

As of May 2024, the members directly represented on the board of directors were JPMorgan Chase (chair), Lloyds Bank (deputy chair), Bank of China, BNP Paribas, BPCE, Citi, Clearstream, Commerzbank, Commonwealth Bank, Deutsche Bank, Euroclear, FirstRand, HSBC, ING, Intesa Sanpaolo, KBC, MUFG, NatWest, Nordea, Royal Bank of Canada, Santander, SEB, UBS (2 representatives following the acquisition of Credit Suisse), as well as the Association of Banks in Singapore.

SWIFT acts as a carrier of the "messages containing the payment instructions between financial institutions involved in a transaction". However, the organisation does not manage accounts on behalf of individuals or financial institutions, and it does not hold funds from third parties. It also does not perform clearing or settlement functions. After payment has been initiated, it must be settled through a payment system, such as T2 in Europe.

In the context of cross-border transactions, this step often takes place through correspondent banking accounts that financial institutions have with each other.

There are four key areas that SWIFT services fall under in the financial marketplace: securities, treasury & derivatives, trade services, and payments & cash management.

SWIFT Ref, the global payment reference data utility, is SWIFT's reference data service. SWIFT Ref sources data from central banks, code issuers and banks.