lemon.markets provides an infrastructure that enables customers to invest in the stock market. Their API allows companies to build customer-centric and compliant investment products. They offer use cases such as vertical brokerage, embedded brokerage, and contextual brokerage to partner with innovative companies and expand investing opportunities across Europe. The company aims to democratize investing and guides partners through operational, technical, and regulatory challenges. Their infrastructure is compatible with various operating models and offers a range of functionalities to support the full value chain of investing.