Carbohydrates are bio-sourced molecules that possess hydroxy functions that are theoretically easy to react with acid functions, activated or not, to give access to new molecules. Taking advantage of this reactivity and considering that carbohydrates have a functionality higher than two, it is possible by using polycarboxylic acids (e.g. malic, maleic, tartaric acid and citric acids) to obtain polyester thermosets. This article aims to review the works carried out in order to obtain cross-linked polyesters from polysaccharides such as cellulose or starch, but also with hydrogenated carbohydrates (e.g. glycerol, erythritol, xylitol, mannitol). We also describe recent results explaining how to obtain polyester networks from Natural Low Transition Temperature Mixtures (NaLTTM):{sugar : polycarboxylic acid : water}, also considered as Brønsted Acidic LTTM. This new strategy not only allows for designing new polyester thermosets but also is eco-friendly and easy to perform without adding any catalyst and at low temperature.