Open-source licences

Last updated 28 August 2026. Hablexo is operated by Hablexo Ltd, a company registered in England & Wales (company no. 17354416). Questions about anything on this page: hello@hablexo.com.

The Hablexo operator applications include software written by other people. This page names it, states the licence each component is under, and — where the licence asks for it — tells you how to obtain the source and build the component yourself. The lists are read from the applications we actually ship, not maintained by hand, so they do not fall behind what is in the download.

The last section covers things the applications download after they are installed rather than carry inside them — the voices that read captions aloud, and the models that read on-screen text. We do not distribute those, but several of them are offered on terms that ask for credit, so they are named here too.

How Hablexo uses copyleft software

Some of what we bundle is licensed under the GNU General Public License. Those components are run as separate programs: Hablexo starts them, passes them work and reads the result back, and none of their code is linked into Hablexo itself. That separation is deliberate, and it is checked against the built application every time we release rather than asserted here — see the note at the end of this page.

There is one exception, and it is an exception the licence itself grants. The compiler runtime libraries on Linux are under the GPL with the GCC Runtime Library Exception, whose stated purpose is to let programs that are not under the GPL — including proprietary ones — use them in exactly this way. Those are linked, and the entries below say so. The exception permits the linking; it does not reduce what we owe you, so their source is listed with the rest.

Where a component is instead linked into the application, it is licensed under terms that allow it — and it is listed that way below, with the source you would need to build your own replacement.

The macOS, Linux and Windows downloads do not contain the same software as each other. Anything below that is only in some of them says so; everything else is in all of them. The copy of this list that ships inside each download names that download alone.

Components under a copyleft licence

• ALSA (alsa-lib) 1.2.6.1 (desktop operator — Linux download only) — the Linux sound system PortAudio opens the microphone through. Licensed under the LGPL-2.1-or-later. Project home: https://www.alsa-project.org/. Source for the version we ship: https://launchpad.net/ubuntu/+source/alsa-lib/1.2.6.1-1ubuntu1.2. Linked into the application.
• Avahi as vendored by cyndilib 0.1.1 (desktop operator — Linux download only) — the mDNS service discovery that finds NDI sources on the network. Licensed under the LGPL-2.1-or-later. Project home: https://avahi.org/. Source for the version we ship: https://github.com/avahi/avahi/releases. Linked into the application.
• certifi 2026.7.22 (desktop operator) — the root-certificate bundle used to verify TLS connections. Licensed under the MPL-2.0. Project home: https://github.com/certifi/python-certifi. Source for the version we ship: https://github.com/certifi/python-certifi. Linked into the application. Used unmodified. The MPL’s obligations attach to modified files, and we modify none.
• Eigen commit 1d8b82b0, as vendored by ONNX Runtime 1.29.0 (desktop operator) — the linear algebra and thread pool inside ONNX Runtime. Licensed under the MPL-2.0. Project home: https://eigen.tuxfamily.org/. Source for the version we ship: https://gitlab.com/libeigen/eigen/-/archive/1d8b82b0740839c0de7f1242a3585e3390ff5f33/eigen-1d8b82b0740839c0de7f1242a3585e3390ff5f33.tar.gz. Linked into the application. Used unmodified. The MPL’s obligations attach to modified files, and we modify none.
• eSpeak NG 1.52.0 (desktop operator) — the universal spoken-audio fallback, and the step that turns text into sounds for both the standard and the premium voices. Licensed under the GPL-3.0-or-later. Project home: https://github.com/espeak-ng/espeak-ng. Source for the version we ship: https://github.com/espeak-ng/espeak-ng/releases/tag/1.52.0. Run as a separate program, never linked into Hablexo.
• FFmpeg 8.1.1 (desktop operator — Linux download only) — encoding spoken-audio clips to Opus or MP3 before they go on the wire. Licensed under the LGPL-2.1-or-later. Project home: https://ffmpeg.org/. Source for the version we ship: https://ffmpeg.org/releases/ffmpeg-8.1.1.tar.xz. Run as a separate program, never linked into Hablexo. On Linux this is an audio-only build of FFmpeg under the LGPL, configured without any of the GPL video encoders.
• FFmpeg 8.1.1 (desktop operator — macOS and Windows download only) — encoding spoken-audio clips to Opus or MP3 before they go on the wire. Licensed under the GPL-3.0-or-later. Project home: https://ffmpeg.org/. Source for the version we ship: https://ffmpeg.org/releases/ffmpeg-8.1.1.tar.xz. Run as a separate program, never linked into Hablexo. This is a GPL build of FFmpeg, configured with --enable-gpl and --enable-version3.
• GCC runtime libraries 12.3.0 (and the builds vendored by NumPy) (desktop operator — Linux and Windows download only) — the C, C++ and Fortran runtime every compiled component on Linux is built against. Licensed under the GPL-3.0-or-later WITH GCC-exception-3.1. Project home: https://gcc.gnu.org/. Source for the version we ship: https://launchpad.net/ubuntu/+source/gcc-12/12.3.0-1ubuntu1~22.04.3. Linked into the application.
• GNU FriBidi 1.0.16, as bundled by Pillow 12.3.0 (desktop operator) — ordering bidirectional text — Arabic, Hebrew — inside Pillow’s text renderer. Licensed under the LGPL-2.1-or-later. Project home: https://github.com/fribidi/fribidi. Source for the version we ship: https://github.com/fribidi/fribidi/releases/tag/v1.0.16. Linked into the application. Used unmodified inside Pillow. Pillow’s own source is public, so the module that uses FriBiDi can be rebuilt against your own copy of it.
• GNU gettext runtime (libintl) 1.0 (desktop operator — Windows download only) — message catalogue lookup behind Tesseract's localisation — reached only from the bundled Tesseract OCR program, never from Hablexo's own code. Licensed under the LGPL-2.1-or-later. Project home: https://www.gnu.org/software/gettext/. Source for the version we ship: https://ftp.gnu.org/gnu/gettext/. Run as a separate program, never linked into Hablexo.
• GNU libiconv 1.19 (desktop operator — Windows download only) — character-set conversion behind Tesseract's text handling — reached only from the bundled Tesseract OCR program, never from Hablexo's own code. Licensed under the LGPL-2.1-or-later. Project home: https://www.gnu.org/software/libiconv/. Source for the version we ship: https://ftp.gnu.org/gnu/libiconv/. Run as a separate program, never linked into Hablexo.
• GNU libidn2 2.3.8 (desktop operator — Windows download only) — internationalised domain names inside curl — reached only from the bundled Tesseract OCR program, never from Hablexo's own code. Licensed under the LGPL-3.0-or-later. Project home: https://www.gnu.org/software/libidn/#libidn2. Source for the version we ship: https://ftp.gnu.org/gnu/libidn/. Run as a separate program, never linked into Hablexo.
• GNU libunistring 1.4.2 (desktop operator — Windows download only) — Unicode string handling behind libidn2 — reached only from the bundled Tesseract OCR program, never from Hablexo's own code. Licensed under the LGPL-3.0-or-later. Project home: https://www.gnu.org/software/libunistring/. Source for the version we ship: https://ftp.gnu.org/gnu/libunistring/. Run as a separate program, never linked into Hablexo.
• JBIG-KIT 2.1 (desktop operator — Windows download only) — JBIG image decoding inside libtiff — reached only from the bundled Tesseract OCR program, never from Hablexo's own code. Licensed under the GPL-2.0-or-later. Project home: https://www.cl.cam.ac.uk/~mgk25/jbigkit/. Source for the version we ship: https://www.cl.cam.ac.uk/~mgk25/jbigkit/download/. Run as a separate program, never linked into Hablexo.
• LAME (libmp3lame) 3.100 (desktop operator) — the MP3 encoder inside the bundled FFmpeg. Licensed under the LGPL-2.0-or-later. Project home: https://lame.sourceforge.io/. Source for the version we ship: https://sourceforge.net/projects/lame/files/lame/3.100/. Run as a separate program, never linked into Hablexo.
• LAME (libmp3lame) 3.100 (mobile operator) — encoding the optional relay of an event's input audio. Licensed under the LGPL-2.0-only. Project home: https://lame.sourceforge.io/. Source for the version we ship: https://sourceforge.net/projects/lame/files/lame/3.100/. Linked into the application. You can replace it: libmp3lame.so inside the Android package; lame.framework inside the iOS app. It is a separate dynamic library, so you can build your own and use it in place of ours.
• Libgcrypt as vendored by cyndilib 0.1.1 (desktop operator — Linux download only) — cryptographic primitives underneath the discovery stack. Licensed under the LGPL-2.1-or-later. Project home: https://gnupg.org/software/libgcrypt/. Source for the version we ship: https://gnupg.org/ftp/gcrypt/libgcrypt/. Linked into the application.
• libgpg-error as vendored by cyndilib 0.1.1 (desktop operator — Linux download only) — the error-reporting library Libgcrypt is built on. Licensed under the LGPL-2.1-or-later. Project home: https://gnupg.org/software/libgpg-error/. Source for the version we ship: https://gnupg.org/ftp/gcrypt/libgpg-error/. Linked into the application.
• pcaudiolib 1.3 (desktop operator — macOS download only) — eSpeak NG's own audio output layer. Licensed under the GPL-3.0-or-later. Project home: https://github.com/espeak-ng/pcaudiolib. Source for the version we ship: https://github.com/espeak-ng/pcaudiolib/releases/tag/1.3. Run as a separate program, never linked into Hablexo.
• pystray 0.19.5 (desktop operator) — the menu-bar / system-tray item the operator launches from. Licensed under the LGPLv3. Project home: https://github.com/moses-palmer/pystray. Source for the version we ship: https://github.com/moses-palmer/pystray. Linked into the application. It is pure Python inside the application, so you can replace it with your own build; the Hablexo EULA does not restrict the rights the LGPL gives you here.
• systemd (libsystemd) as vendored by cyndilib 0.1.1 (desktop operator — Linux download only) — the journal and socket helpers the discovery stack links. Licensed under the LGPL-2.1-or-later. Project home: https://systemd.io/. Source for the version we ship: https://github.com/systemd/systemd/releases. Linked into the application.
• util-linux (libblkid, libmount) as vendored by cyndilib 0.1.1 (desktop operator — Linux download only) — block-device and mount-point lookups underneath the NDI discovery stack. Licensed under the LGPL-2.1-or-later. Project home: https://www.kernel.org/pub/linux/utils/util-linux/. Source for the version we ship: https://www.kernel.org/pub/linux/utils/util-linux/. Linked into the application.
• x264 r3222 (desktop operator — macOS and Windows download only) — an H.264 encoder inside the bundled FFmpeg; Hablexo itself never calls it. Licensed under the GPL-2.0-or-later. Project home: https://www.videolan.org/developers/x264.html. Source for the version we ship: https://code.videolan.org/videolan/x264. Run as a separate program, never linked into Hablexo.
• x265 4.2 (desktop operator — macOS and Windows download only) — an H.265 encoder inside the bundled FFmpeg; Hablexo itself never calls it. Licensed under the GPL-2.0-or-later. Project home: https://bitbucket.org/multicoreware/x265_git/src/master/. Source for the version we ship: https://bitbucket.org/multicoreware/x265_git/downloads/. Run as a separate program, never linked into Hablexo.

Components under permissive licences

Components that are not open source

These are distributed with the applications under their vendors' own terms.

• Microsoft Universal C Runtime (10.0.26100.1742 — Windows download only) — the C runtime the frozen application and every bundled program are compiled against. Distributed under the Microsoft Software License Terms (Windows SDK / Visual Studio distributable code), published at https://learn.microsoft.com/en-us/visualstudio/releases/2022/redistribution.
• Microsoft Visual C++ Runtime (14.51.36231.0 — Windows download only) — the C++ runtime the frozen application and its extension modules are compiled against. Distributed under the Microsoft Software License Terms (Visual Studio 2022 distributable code), published at https://learn.microsoft.com/en-us/visualstudio/releases/2022/redistribution.
• Microsoft Windows API sets (10.0.26100.1742 — Windows download only) — the Windows API forwarders the runtime resolves core OS calls through. Distributed under the Microsoft Software License Terms (Windows SDK / Visual Studio distributable code), published at https://learn.microsoft.com/en-us/visualstudio/releases/2022/redistribution.
• NDI SDK (as shipped with cyndilib 0.1.1) — receiving the on-screen graphics feed and sending the lower-third back. Distributed under the NDI SDK licence (Vizrt NDI AB), published at http://ndi.link/ndisdk_license. NDI® is a registered trademark of Vizrt NDI AB. The SDK’s own notice file is included with the application.

Things the applications download after installation

The applications can download a few things after they are installed: the voices that read captions aloud, and the models that read on-screen text. None of this is distributed with Hablexo — your own computer fetches each one from the people who publish it, only when it is first needed. It is listed here anyway, because several of the voice recordings are offered under licences that permit commercial use on condition their source is credited, and this is that credit.

• Piper voices (desktop operator) — the standard spoken-voice tier. Downloaded the first time a language needs a standard voice, from https://huggingface.co/rhasspy/piper-voices. Licensed under MIT for the collection; each voice under the licence of its own recordings. The collection's own MIT licence describes the repository, not the recordings each voice was trained on — those are listed separately below, because several of them ask to be credited and this is that credit.
• Kokoro-82M (desktop operator) — the premium spoken-voice tier. Downloaded only when someone installs the premium voice pack (~195 MB), from https://huggingface.co/hexgrad/Kokoro-82M. Licensed under Apache-2.0. Downloaded as ONNX files from the kokoro-onnx release page.
• UniDic (unidic-mecab, via unidic-lite) (desktop operator) — reading Japanese kanji, which the premium Japanese voice cannot do without it. Downloaded only when someone installs the Japanese voice pack (~250 MB), from https://clrd.ninjal.ac.jp/unidic/. Licensed under BSD-3-Clause. Offered by its authors under a choice of three licences; Hablexo uses it under the BSD one.
• Tesseract trained data (tessdata_fast) (desktop operator) — reading on-screen text in a language other than English. Downloaded when on-screen text is read in a language whose model is not already installed, from https://github.com/tesseract-ocr/tessdata_fast. Licensed under Apache-2.0. The English and orientation models ship inside the application; every other language is downloaded from the same project when it is first needed.

The standard voices, and the recordings each one was trained on

One row per language the standard voice tier covers. The licence is the one on the recordings, which is the fact that governs — the collection they are published in carries a different licence of its own, and it does not speak for them.

Written offer of source, and your right to replace a component

For every component above under the GNU General Public License or the GNU Lesser General Public License, the source of the version we ship is linked beside it, and those links also travel with the download — in THIRD-PARTY-NOTICES.txt inside the application folder and beside the installers on our releases page. That is what GPL v3 section 6(d) asks for: directions to the source, next to the object code.

In addition, as a written offer valid for three years from the date you received the software, we will send you the complete corresponding source code and the scripts used to build and install it, for any of those components, if you write to hello@hablexo.com. We will supply it for no more than the cost of distribution.

Nothing in the Hablexo EULA takes away a right one of these licences gives you. Its section 3 carves out anything an included component's open-source licence permits, and its section 6 says so directly — including the rights the LGPL grants to modify a component for your own use, to reverse engineer for debugging those modifications, and to replace the component with your own build.

How we keep this page honest

Every component listed here was read out of a built application: its shared libraries, the programs bundled beside it, and every Python package inside it, each with the licence it declares about itself. A build containing anything not on this page fails before it can be signed, and so does a build in which copyleft code has found its way into Hablexo's own process. We would rather the check refused a release than have this page quietly describe last year's download.

Hablexo Ltd · Registered in England & Wales · Company No. 17354416 · Registered office: 167-169 Great Portland Street, 5th Floor, London W1W 5PF · hello@hablexo.com

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