Tether is a stablecoin – a digital currency whose value aims to maintain a stable value relative to the United States dollar – launched by Tether Limited in 2014. It is represented by its currency codes USD₮ and USDT.

In August 2026, KPMG U.S. completed Tether International's first full independent audit of its financial statements and issued an unqualified opinion under U.S. generally accepted accounting principles.

Tether is one of the largest cryptocurrency companies in terms of trading volume, holding 70% of the market share among stablecoins. In 2019, it surpassed bitcoin to become the most traded cryptocurrency globally. As of July 2024, Tether has more than 350 million users worldwide. Tether Limited is owned by iFinex, a company based in the British Virgin Islands which also operates the Bitfinex cryptocurrency exchange. As of January 2024, Tether's official website lists fourteen protocols and blockchains on which Tether has been minted.

Tether faces criticism regarding the transparency and verifiability of its stated fiat reserves. In addition to publishing quarterly attestations, Tether provides regularly updated information on token circulation and reserves on its official transparency page, including blockchain-level supply data across supported networks.

In 2012, J. R. Willett published a white paper that described the possibility of building new cryptocurrencies on top of the bitcoin blockchain. Willett went on to help implement this idea in the cryptocurrency Mastercoin, which had an associated Mastercoin Foundation (later renamed the Omni Foundation). to promote the use of this new "second layer".

The Mastercoin protocol became the technological foundation of the Tether cryptocurrency, and Brock Pierce (one of the original members of Mastercoin Foundation) became a co-founder of Tether while Tether founder Craig Sellars became the CTO of the Mastercoin Foundation.

The precursor to Tether, originally named "Realcoin", was announced in July 2014 by co-founders Brock Pierce, Reeve Collins, and Craig Sellars as a Santa Monica-based startup. The first tokens were issued on 6 October 2014, on the bitcoin blockchain.^([non-primary source needed]) Realcoin used bitcoin's computer infrastructure to exchange property and execute contracts without third-party intermediaries, enabling additional commercial uses on the bitcoin network.

Realcoin worked with banks, digital-currency exchanges, and ATM providers to become "gateways" for buying, trading, or redeeming realcoins around the world.

On 20 November 2014, Tether CEO Reeve Collins announced the project was being renamed to "Tether". The company also announced it was entering private beta, which supported a "Tether+ token" for three currencies: USTether (US+) for United States dollars, EuroTether (EU+) for euros, and YenTether (JP+) for Japanese yen.

In January 2015, the cryptocurrency exchange Bitfinex enabled trading of Tether on their platform. In 2018, Phil Potter, the chief strategy officer for Bitfinex, left the company after the Paradise Papers leaks in November 2017 named Bitfinex officials Philip Potter and Giancarlo Devasini as responsible for setting up Tether Holdings Limited in the British Virgin Islands in 2014. The Financial Times reported in 2022 that Devasini and Jan Ludovicus van der Velde founded two companies in 2012 and 2014, respectively, Bitfinex and Tether.

Tether Limited is a fully owned subsidiary of British Virgin Islands–based Tether Holdings Limited.

For a short period, Tether managed United States dollar transactions through Taiwanese banks, which worked with Wells Fargo to enable the transfer of funds outside of Taiwan. On 18 April 2017, Tether shared that these international transfers had come to a stop.^([unreliable source?]) Tether issues tokens on Algorand, Avalanche, Celo, Ethereum, EOS, Liquid Network, Near, Polygon, Solana, Bitcoin Cash's Standard Ledger Protocol, Statemint, Tezos, and Tron.^([non-primary source needed])

There are a total of five distinct Tether tokens: United States dollar tether (USD₮) on bitcoin's Omni layer, euro tether (EUR₮) on bitcoin's Omni layer, United States dollar tether (USD₮) as an ERC-20 token, and euro tether (EUR₮) as an ERC-20 token, and added in 2020 United States dollar tether (USD₮) as a TRC-20 token on the TRON network. In August 2024, Tether announced that they would be launching a stablecoin pegged to the United Arab Emirates dirham. The dirham, like several Gulf currencies, is pegged to the United States dollar.

From January 2017 to September 2018, the amount of tethers outstanding grew from about $10 million to about $2.8 billion. In early 2018, Tether accounted for about 10% of the trading volume of bitcoin, but during the summer of 2018, it accounted for up to 80% of bitcoin volume. More than $500 million of Tether was issued in August 2018. On 15 October 2018, the tether price briefly fell to $0.88 due to the perceived credit risk as traders on Bitfinex exchanged tether for bitcoin, driving up the price of bitcoin.

The Wall Street Journal reported that in late 2018, Tether Holdings Ltd former co-owner Stephen Moore discussed efforts by a major Tether trader in China to "circumvent the banking system by providing fake sales invoices and contracts for each deposit and withdrawal", and the report quoted a Moore email in which he admitted signing these fake invoices and contracts but said he "would not want to argue any of the above in a potential fraud/money laundering case." Tether released a response calling the report "wholly inaccurate and misleading" but did not cite any specific inaccuracies.

In 2019, Tether surpassed bitcoin in trading volume with the highest daily and monthly trading volume of any cryptocurrency on the market. As of July 2021, Tether is tied to half of all bitcoin trades. Also in 2021, the company was fined by the CFTC for only maintaining full reserves during 27.6% of the days in the period from 2016 to 2018 as well as for failing to present audits showing sufficient asset reserves, an issue that Tether has since addressed. In May 2022, Tether launched its MXNT token pegged to Mexico's peso as a "testing ground" in Latin America.

Tether continued operating in 2022 when several cryptocurrency and banking companies collapsed. Tether's nearest competitor, Circle, experienced a faltered growth to the point where its $24 billion of USDC was worth barely more than a quarter of Tether's stash.

In October 2023, Paolo Ardoino, the chief technology officer for Tether, was promoted to CEO. He has led the company since December 2023, succeeding current CEO Jean-Louis van der Velde. In October 2023, The Wall Street Journal reported that Tether has been increasingly showing up in investigations tied to money laundering, terror financing, and sanctions evasion. Research firm Elliptic later disputed the report's accuracy, saying it has engaged with The Wall Street Journal to correct misinterpretations of the level of crypto fundraising by Hamas.

In response, the company published a blog post denying inadequate customer due diligence and screening practices. It described how they have aided governments with criminal investigations, helping freeze $835 million in assets linked to theft. The company reported in 2024 that they have worked with more than 140 law enforcement offices across 45 jurisdictions to assist cases involving illicit stablecoin use.