Tagnet is a state-of-the-art API for automatic text classification, keyword and concept extraction. It extracts keywords and annotates named entities from content. Tagnet uses the extracted tags organized in a graph structure to classify content into a single thematic category and can customize categories. It also returns concepts that describe the main content, such as subcategories. Tagnet has an overall accuracy of 87% for classification and provides a demo that currently supports Polish language categories including beauty, cuisine, moto and sports.