Hack is hand groomed and optically balanced to be a workhorse face for code. It has deep roots in the libre, open source typeface community and expands upon the contributions of the Bitstream Vera & DejaVu projects.
The face has been re-designed with glyph set expansions, modifications of the original glyph shapes (including distinct point styles and semi-bold punctuation weight in the regular set to make analphabetic characters less transparent), and meticulous attention to metrics (including numerous spacing adjustments to improve the rhythm of the face and the legibility of code at small text sizes).
The large x-height + wide aperture + low contrast design combined with PostScript hinting/hint replacement programs and a TrueType instruction set make it highly legible at commonly used source code text sizes with a sweet spot that runs in the 8px - 12px range on modern desktop and laptop monitors. The full set of changes are available in the changelog.
The font binaries are released under a license that permits unlimited print, desktop, and web use for commercial and non-commercial applications. It may be embedded and distributed in documents and applications. The source is released in the widely supported UFO format and may be modified to derive new typeface branches. The full text of the license is available in LICENSE.md
Click the image for the full type specimen.