~/.opendexd/opendex.conf on Linux or AppData\Local\OpenDEX\opendex.conf on Windows. Run opendexd at least once for this folder to be created. The opendexd repository contains an up-to-date sample-opendex.conf which serves as template for creating opendex.conf. It is possible to overwrite the default data directory by launching opendexd with opendexd --opendexdir=/path/to/custom/opendexdir.opendexd --help)