Platformism is a tendency within the wider (semi)-libertarian movement which shares an affinity with organising in the tradition of Nestor Makhno and the "Organizational Platform of the Libertarian Communists". The Platform came from the experiences of Russian libertarians in the 1917 October Revolution, which lead eventually to the victory of Bolshevik party dictatorship rather than workers' and peasants' self-management. The Platform attempts to explain and address the failure of the libertarian movement during the Russian Revolution. The "Organizational Platform of the Libertarian Communists" was written in 1926 by the Dielo Trouda (Workers' Cause) group, a group of exiled Russian (semi-) libertarians in France. The Platformism was mainly developed by Peter A. Arshinov, an associate of Makhno, who went over the border to marxism on the Economical-Political Map and later joined the Bolsheviks, and it should be rejected as not being anarchism, but in reality being semilibertarian or authoritarian marxism. The four main principles by which an "anarchist" organization should operate, according to the Platform, are ideological unity, tactical unity, collective action and discipline, and federalism.
Thus they use majority ruling over minorities and a central commitee for decision making. As anarchism is neither majority that rules minority, nor minority that rules majoritiy, this is clearly unanarchistical. Majority dictatorship is no better than minority dictatorship. In a truly anarchist federation, an anarchist direct democracy,
there is a free agreement that secure that the minority is free to do whatever they want as long as they not actively try to stop the majority to do what they have decided, i.e. for their own part only. This is far from platformism. This anarchist form of direct democracy is adopted by the Anarchist International and all the associated federations, including the Norwegian Anarchist Federation, AFIN.
In the "Organizational Platform of the Libertarian Communists", they attempted to explain and understand why the people's revolution failed and the Bolsheviks won. They decided that among the main causes were that the anarchists were not disciplined and dedicated (and ruthless?) enough. As a result, they attempted to emulate the political formation of the victorious Bolsheviks (democratic centralism, an untouchable central committee) without using the terminology of the Bolsheviks. They wanted to out-Bolshevize the Bolsheviks, in the hopes of winning the next round of the struggle. It was for these reasons that the Platform was publicly condemned by ex-Makhnovists (including Voline), anarcho-communists (like Malatesta), and others as being a sectarian attempt to create an "anarchist" program with a Bolshevik organizational structure. The Platform project was unsuccessful.
There is a nagging question in this organizational discussion: why have the promoters of formally structured membership organizations taken an example from a historically unimportant document, an example of unrivalled ineffectiveness? The "anarcho"-communism of the Platformists is very similar to the authoritarian communism of various Leninist gangs. From a cursory examination of their published rhetoric, it is difficult not to conclude that they have taken the "successful" aspects of a Leninist program, a Leninist vision, and Lenino-Maoist organizing, and more or less removed or modified the vocabulary of the more obviously statist parts. The promoters of this hybridized leninistoid "anarchism", are in reality not anarchist, but semilibertarian leftists, i.e. marxian on the economical-political map - outside the anarchist quadrant. Thus, Platformism is not anarcho-communism in the Kropotkinian and Malatestian tradition, on the top of the economical-political map. Platformism is a tendency of the semilibertarian left, outside the anarchist movement, broadly defined.
The platformists of today is connected to the international so called "Anarkismo.net"-project. However, as mentioned, these groups are not anarchists, but semilibertarian leftists, i.e. marxists.