#font #db #css #truetype #ttf

no-std fontdb

A simple, in-memory font database with CSS-like queries

29 releases (15 breaking)

0.16.0 Oct 31, 2023
0.14.1 May 10, 2023
0.13.0 Feb 21, 2023
0.11.1 Dec 26, 2022
0.2.0 Jul 21, 2020

#73 in Text processing

Download history 15523/week @ 2023-08-07 16680/week @ 2023-08-14 14311/week @ 2023-08-21 12246/week @ 2023-08-28 14112/week @ 2023-09-04 13336/week @ 2023-09-11 13595/week @ 2023-09-18 14636/week @ 2023-09-25 14608/week @ 2023-10-02 14580/week @ 2023-10-09 15222/week @ 2023-10-16 18908/week @ 2023-10-23 19551/week @ 2023-10-30 17503/week @ 2023-11-06 18995/week @ 2023-11-13 17198/week @ 2023-11-20

75,085 downloads per month
Used in 115 crates (18 directly)

MIT license



Build Status Crates.io Documentation Rust 1.60+

fontdb is a simple, in-memory font database with CSS-like queries.


  • The database can load fonts from files, directories and raw data (Vec<u8>).
  • The database can match a font using CSS-like queries. See Database::query.
  • The database can try to load system fonts. Currently, this is implemented by scanning predefined directories. The library does not interact with the system API.
  • Provides a unique ID for each font face.


  • Advanced font properties querying.
    The database provides only storage and matching capabilities. For font properties querying you can use ttf-parser.

  • A font fallback mechanism.
    This library can be used to implement a font fallback mechanism, but it doesn't implement one.

  • Application's global database.
    The database doesn't use static, therefore it's up to the caller where it should be stored.

  • Font types support other than TrueType.

Font vs Face

A font is a collection of font faces. Therefore, a font face is a subset of a font. A simple font (*.ttf/*.otf) usually contains a single font face, but a font collection (*.ttc) can contain multiple font faces.

fontdb stores and matches font faces, not fonts. Therefore, after loading a font collection with 5 faces (for example), the database will be populated with 5 FaceInfo objects, all of which will be pointing to the same file or binary data.


The database performance is largely limited by the storage itself. We are using ttf-parser, so the parsing should not be a bottleneck.

For example, on Mac Book Pro 14 with M1 Pro, it takes just ~24ms to load 1361 font faces.


The library relies on memory-mapped files, which is inherently unsafe. But since we do not keep the files open it should be perfectly safe.

If you would like to use a persistent memory mapping of the font files, then you can use the unsafe Database::make_shared_face_data function.




~33K SLoC