The Block Copolymer Database (BCDB) is a database platform that allows a user to search, submit, visualize, and download experimental phase measurements and their associated characterization information for di- and multi-block copolymers. This database template can accommodate any number of blocks and at the time of publication contains over 5,300 block copolymer melt phase measurements mined from literature and manually curated. The chemical structure of the polymer is encoded in BigSMILES, an extension of the Simplified Molecular-Input Line-Entry System (SMILES) into the macromolecular domain, and the user can search repeat units and functional groups using the search syntax SMARTS (SMILES Arbitrary Target Specification). The user can also query characterization and phase information using the Structured Query Language (SQL). This platform is an important step in making polymer data more accessible to the broader community, facilitates benchmarking and visualization of new data against existing samples, enables to user to search and download custom sets of block copolymer data from the literature, and will drive the development of data-driven models and machine learning applications.