This review discusses the transesterification of vegetable oils with methanol, focusing on the production of fatty acid methyl esters (FAMEs) and their various applications. The process involves the transformation of triglycerides into alkyl esters and glycerol, catalyzed by different types of catalysts, including acids, bases, enzymes, and non-ionic bases. Special attention is given to guanidines, which can be heterogenized on organic polymers but face leaching issues. New strategies to improve the stability of these catalysts are proposed. The review also covers the industrial applications of FAMEs, such as biodiesel production and the use of fatty acid esters of carbohydrates as non-ionic biodegradable surfactants or non-caloric food substitutes. The authors highlight the potential of guanidine-containing polymers for heterogeneous catalysis and discuss the challenges and future perspectives in this field.This review discusses the transesterification of vegetable oils with methanol, focusing on the production of fatty acid methyl esters (FAMEs) and their various applications. The process involves the transformation of triglycerides into alkyl esters and glycerol, catalyzed by different types of catalysts, including acids, bases, enzymes, and non-ionic bases. Special attention is given to guanidines, which can be heterogenized on organic polymers but face leaching issues. New strategies to improve the stability of these catalysts are proposed. The review also covers the industrial applications of FAMEs, such as biodiesel production and the use of fatty acid esters of carbohydrates as non-ionic biodegradable surfactants or non-caloric food substitutes. The authors highlight the potential of guanidine-containing polymers for heterogeneous catalysis and discuss the challenges and future perspectives in this field.