Platform as a service (PaaS) featuring computer software platforms for accessing financial trading algorithms for use in transacting, trading, and executing of financial securities; providing temporary use of non-downloadable software for accessing financial trading algorithms for use in transacting, trading, and executing of financial securities; providing temporary use of non-downloadable software for accessing financial trading algorithms for sourcing financial liquidity; providing temporary use of non-downloadable software that allows users to customize and deploy a financial trading algorithm.