The International Socialist Alliance (ISA) was a worldwide organisation of democratic socialist political parties, founded by the Democratic Socialist Party (UK), the Worker's Party (USA) and Die Linke (Germany).
By the time the Worker's Party collapsed in October 2020, the ISA had stagnated. Though it was never formally dissolved, it no longer exists as an organized alliance.
The DSP and Die Linke still maintain informal ties, along with several leftist parties in other countries, but an official successor to the ISA has yet to be established.