ABSTRACT: BACKGROUND: Life Science Identifiers (LSIDs) are persistent, globally unique identifiers for biological objects. The decentralised nature of LSIDs makes them attractive for identifying distributed resources. Data of interest to biodiversity researchers (including specimen records, images, taxonomic names, and DNA sequences) are distributed over many different providers, and this community has adopted LSIDs as the identifier of choice. RESULTS: LSID Tester is a web application written in PHP. Given a LSID the application performs seven tests, reporting the results at each step. If all tests are successful the metadata associated with the LSID is displayed, and can be viewed in a range of formats. CONCLUSION: The software provides a tool for testing a LSID resolution service.