This online tool allows you to search the database described in Holdship & Viti 2021. This is a list of species transitions and ratios which are particularly informative about a given physical parameter and are insensitive to chemical history of the gas making them ideal probes of physical conditions. Holdship & Viti 2021 gives a full explanation and an overview of the best transitions to observe but this tool will allow you to find the most informative species considering any observational limitations such as bandwidth or possible frequency ranges.