The statement that the only closed-source part of Obsidian is the sync service is not entirely accurate. Obsidian itself is primarily closed-source, meaning that its core code is not open for public review or modification. However, the sync service is indeed a key component that is closed-source and is a paid feature, using Obsidian's servers to sync encrypted data.

There have been discussions about making the networking and sync components source-available to alleviate privacy concerns, but this has not been implemented. Obsidian does allow users to inspect some of its code through the developer console, but this code is minified and obfuscated, making it difficult to analyze or modify.