HarfBuzz

HarfBuzz started as a text shaping engine but has grown into a full font platform — the ffmpeg of text shaping. It primarily supports OpenType, but also Apple Advanced Typography.

HarfBuzz shapes the majority of text on modern screens.

HarfBuzz is optimized for robustness, correctness, and performance — in that order. Achieve all.

Try it live at harfbuzz-world.cc — an interactive playground for shaping, subsetting, rasterization, vector output, and GPU rendering, all running in your browser.

Here is a quick map of its components:

Core libraries

Library	Description
libharfbuzz	Text shaping, draw API, paint API. Highly configurable (see CONFIG.md). Optional integration backends compiled in: hb-ft (FreeType), hb-coretext (macOS), hb-uniscribe (Windows), hb-directwrite (Windows), hb-gdi (Windows), hb-glib, hb-graphite2.
libharfbuzz-subset	Font subsetting and variable-font instancing.

Auxiliary libraries

Library	Description
libharfbuzz-icu	ICU Unicode integration.
libharfbuzz-cairo	Cairo rendering integration.
libharfbuzz-gobject	GObject/GI bindings.

Experimental libraries

Library	Description
libharfbuzz-raster	Glyph rasterization to bitmaps, including color fonts. Uses hb-draw and hb-paint.
libharfbuzz-vector	Glyph output to vector formats (currently SVG), including color fonts. Uses hb-draw and hb-paint.
libharfbuzz-gpu	Encodes glyph outlines for GPU rasterization (Slug algorithm). Provides shader sources in GLSL, WGSL, MSL, and HLSL. Live demo.

Notable missing feature: font hinting (including autohinting) is not implemented. For hinted rasterization, use FreeType or Skrifa.

For simplified builds, amalgamated sources are available: harfbuzz.cc (just libharfbuzz), harfbuzz-subset.cc (just libharfbuzz-subset), or harfbuzz-world.cc (everything, driven by a custom hb-features.h). For a live in-browser playground plus a worked example of the world.cc single-file build, see harfbuzz-world.cc.

Command-line tools

Tool	Description
hb-shape	Shape text and display glyph output.
hb-view	Render shaped text to an image.
hb-subset	Subset and optimize fonts.
hb-info	Display font metadata.
hb-raster	Render glyphs to bitmap images.
hb-vector	Render glyphs to vector formats (SVG).
hb-gpu	Interactive GPU text rendering.

The canonical source tree and bug trackers are available on github. Both development and user support discussion around HarfBuzz happen on github as well.

For license information, see COPYING.

API stability

The API that comes with hb.h will not change incompatibly. Other, peripheral, headers are more likely to go through minor modifications, but again, we do our best to never change API in an incompatible way. We will never break the ABI.

The API and ABI are stable even across major version number jumps. In fact, current HarfBuzz is API/ABI compatible all the way back to the 0.9.x series. If one day we need to break the API/ABI, that would be called a new library.

As such, we bump the major version number only when we add major new features, the minor version when there is new API, and the micro version when there are bug fixes.

Documentation

For user manual as well as API documentation, check: https://harfbuzz.github.io

Download

Tarball releases and Win32/Win64 binary bundles are available on the github releases page.

Development

For build information, see BUILD.md.

For custom configurations, see CONFIG.md.

For testing and profiling, see TESTING.md.

For using with Python, see README.python.md. There is also uharfbuzz.

For cross-compiling to Windows from Linux or macOS, see README.mingw.md.

To report bugs or submit patches please use github issues and pull-requests.

Developer documents

To get a better idea of where HarfBuzz stands in the text rendering stack you may want to read State of Text Rendering 2024. Here are a few presentation slides about HarfBuzz over the years:

• 2026 – HarfBuzz at 20!
• 2016 – Ten Years of HarfBuzz
• 2014 – Unicode, OpenType, and HarfBuzz: Closing the Circle
• 2012 – HarfBuzz, The Free and Open Text Shaping Engine
• 2009 – HarfBuzz: the Free and Open Shaping Engine

More presentations and papers are available on behdad‘s website. In particular, the following studies are relevant to HarfBuzz development:

• 2025 – AAT layout caches
• 2025 – OpenType Layout lookup caches
• 2025 – Introducing HarfRust
• 2025 – Subsetting
• 2025 – Caching
• 2025 – hb-decycler
• 2022 – hb-iter
• 2022 – A C library written in C++
• 2022 – The case of the slow hb-ft >h_advance function
• 2022 – PackTab: A static integer table packer
• 2020 – HarfBuzz OT+AAT “Unishaper”
• 2014 – Building the Indic Shaper
• 2012 – Memory Consumption

Name

HarfBuzz /hærfˈbɒːz/

From Persian حرف (Harf: letter) and باز (Buzz: open). Transliteration of the Persian calque for OpenType.

As a noun: The Open Source text shaping engine.

As an adjective: Insincerely talkative; glib. A nod to the GNOME project where HarfBuzz originates from.

The logo shows حرف‌باز in the IranNastaliq font, on a Damascus steel background.

Background: Originally there was this font format called TrueType. People and companies started calling their type engines all things ending in Type: FreeType, CoolType, ClearType, etc. And then came OpenType, which is the successor of TrueType. So, for my OpenType implementation, I decided to stick with the concept but use the Persian translation. Which is fitting given that Persian is written in the Arabic script, and OpenType is an extension of TrueType that adds support for complex script rendering, and HarfBuzz is an implementation of OpenType text shaping.

Users

HarfBuzz is used in Android, Chrome, ChromeOS, Firefox, Flutter, GNOME, GTK+, KDE, Qt, LibreOffice, OpenJDK, XeTeX, Adobe Photoshop, Illustrator, InDesign, Microsoft Edge, Amazon Kindle, PlayStation, Godot Engine, Unreal Engine, Figma, Canva, QuarkXPress, Scribus, smart TVs, car displays, and many other places.

Distribution

Packaging status of HarfBuzz