Freshwater algae are considered a very important resource within the food industry due to their high nutritional content and bioactive compounds. This review article aims to address microalgae and macroalgae as alternative/complementary protein sources and explore their potential applications in food products. The main types of freshwater microalgae (including cyanobacteria such as Arthrosporic and green algae such as Chlorella, Scenedesmus, and Haematococcus) are described, their morphology, ecological relevance, and applications (food, nutraceutical, and industrial). Likewise, the extraction and application methods of their components (conventional, ultrasonic, Soxhlet, microwave, CO2 (SFE) are detailed, comparing principles, operating parameters, yields, and benefits for the industry. The proximate and micronutrient composition of each algae (proteins, carbohydrates, lipids, ash, mois...