Download of Libretto 4.7.5 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The application lies within Productivity Tools, more precisely Office Tools. The actual developer of this free Mac application is Denk Alexandru. We recommend checking the downloaded files with any free antivirus.
From the developer:
Libretto is designed to help you convert audio and video files to text. Also, the utility can translate the resulting transcription to any language. You can use this app to take notes from recorded meetings, interviews, courses or movies. The free version can transcribe an unlimited number of files, but only up to 5 paragraphs.
You may want to check out more Mac applications, such as PDFMergeThing, NanoCount or CryptoEdit, which might be related to Libretto.