Server
The AcoustID server is a set of applications written in Python: this website, the web service that applications use to look up and submit fingerprints, and background workers that import submissions and keep the statistics up to date. The data is stored in PostgreSQL.
Fingerprint searches go to acoustid-index, a custom index server designed specifically for searching audio fingerprints.
The source code is licensed under the MIT License. You can download it from GitHub.