GoldenDict is described as 'Open-source dictionary program for PC computers that gives translations of words and phrases for different languages. It allows use of several popular dictionary file formats simultaneously' and is a very popular Dictionary in the education & reference category. There are more than 50 alternatives to GoldenDict for a variety of platforms, including Android, Web-based, Windows, Linux and iPhone apps. The best GoldenDict alternative is Wiktionary, which is both free and Open Source. Other great apps like GoldenDict are GoldenDict-ng, WordReference, FreeDictionaryApp and Lingoes.
OpenDict doesn't support popular formats, such as StarDict, Slob, or Mdict, but can work with their own format and two less common (Slowo and Mova). However, support of custom plugins (Python?) makes it a very strong rival. Hope, the new developer will continue work on improving this application.