We describe a fragment screening platform (PhABits) that uses a photoreactive group (diazirine) to capture fragmentprotein binding. The approach is straightforward to implement and can be directly applied to purified proteins without the requirements of more traditional assay development. The PhABits, along with other covalent fragment approaches, offer rapid assessment of tractability and tool generation on timescales suitable for application to the large numbers of targets emerging from functional genomics analyses. In this way, the platform complements other binding assay approaches, such as ASMS and DELs, which are not typically compatible with fragments.