This article reviews available methods for the formation of alginate nano-aggregates, nanocapsules and nanospheres. Primarily, alginate nanoparticles are being prepared by two methods. In the “complexation method”, complex formation on the interface of an oil droplet is used to form alginate nanocapsules, and complex formation in an aqueous solution is used to form alginate nano-aggregates. In a second method w/o emulsification coupled with gelation of the alginate emulsion droplet can be used to form alginate nanospheres. We review advantages and disadvantages of these methods, and give an overview of the properties of the alginate particles produced with these methods. Display omitted •Alginate is one of the most used polymers in formation of (micro)particles.•Use of alginate in nanoparticles is not common.•Alginate nano-aggregates, nanocapsules and nanospheres are reviewed.•Alginate nanoparticle formation is based on two methods.•These are complexation and w/o emulsification