Panic founder Steven Frank admitted in a blog post that it happened after he downloaded an infected copy of the video encoding tool Handbrake.
He said there was no sign that any customer data was accessed and that Panic's web server was not affected.
Users have been warned to download Panic's apps only from its website or the Apple App Store.
Panic is the creator of web editing and file transfer apps Coda and Transmit, and the video game Firewatch.
