The iA Writer fonts comes bundled with iA Writer for for Android, Windows, Mac, iPadOS and iOS.
In-depth explanation of iA Writer Mono, Duo, and Quattro is available iA Writer's blog entry on Duospace and on iA Writer Mono, Duo, and Quattro.
This is a modification of IBM's Plex® Mono typeface which is available under SIL Open Font License, Version 1.1.
If you fork or use these fonts, reference iA Writer clearly.
This fork fixes known iA Writer's typeface issues such as omitted "monospaced" proportion info, Quattro's font incorrect weight info and Windows Font Viewer's rendering issues.
Fonts were imported, corrected and then generated using FontForge. Only metadata was corrected with the exception of "iA Writer Mono S" typeface.