Flite

Free plan AndroidAPILinuxMacSelf-hostedWindows

What Flite is

Flite is a free, open-source run-time text-to-speech engine for converting text into spoken audio. Its command-line program synthesizes strings or files to audio devices or WAV waveform files, while its ANSI C library provides functions for embedding speech in applications. It is designed for small devices such as phones and PDAs and for servers handling many ports. Flite compiles and runs without Festival or FestVox. The distribution includes one 8K diphone voice, a pruned lexicon, and US English models; other voices can be downloaded or loaded from disk or HTTP. The project describes Indic support and grapheme support for hundreds of languages. Voice, lexicon, and language data can be compiled into C or loaded at runtime. Flite is thread-safe after initialization, supports commercial use under BSD-like core terms, and exports WAV audio. The included voice uses fewer resources but sounds more robotic.

Who it suits

Flite suits developers building speech into applications, small devices, or high-volume servers. It also fits users needing open-source speech synthesis with commercial-use rights for the core code.

What it does well

Free open-source engine
ANSI C library and command line
Runs on small devices and servers
Additional voices load from disk or HTTP
Commercial use allowed for core code

What to know first

Bundled voice sounds robotic
Only one voice included
Some included files have separate licenses
Debug feature options can stop operation

Plans

Plan	Billed and limits	Price
Flite	Open source speech synthesis engine · single 8K diphone voice included	Free

As github.com lists them, read 12 Oct 2026. The maker's own page has the final word.

Verdict

Flite provides a compact speech engine with command-line and library interfaces, WAV output, and multiple deployment options. Its included voice favors low resource use over naturalness, so voice quality and licensing of included files deserve attention.

Facts from Flite's own pages

API access: Yes · github.com, 20 Sept 2026
Commercial use: Yes · github.com, 20 Sept 2026
Companion app: The README describes Bard Storyteller as an app that reads text, HTML, and EPUB ebooks aloud using Flite. · github.com, 12 Oct 2026
Deployment: Voice, lexicon, and language data can be compiled into C representations and linked into an application, and voice files may also be loaded from disk or HTTP. · github.com, 12 Oct 2026
Export formats: WAV · github.com, 20 Sept 2026
Features: The command-line program synthesizes strings or files to audio devices or waveform files, and the library provides simple functions for applications. · github.com, 12 Oct 2026
Implementation: The engine is written in ANSI C and does not require Festival or FestVox to compile or run. · github.com, 12 Oct 2026
Integration: Flite can be used as a library in applications, and the repository documents SAPI support for clustergen voices. · github.com, 12 Oct 2026
Languages: The project describes Indic language support and hundreds of languages through grapheme support. · github.com, 12 Oct 2026
License: The project says the core code is free to use in commercial products under its BSD-like copyright terms; some included files have separate licenses. · github.com, 12 Oct 2026
Platforms: The project reports successful builds on Linux, Mac OS X, Android, FreeBSD, Solaris, Windows through Cygwin or Windows Subsystem for Linux, and experimental WASI. · github.com, 12 Oct 2026
Purpose: Flite is a small, fast, open source run-time text-to-speech engine. · github.com, 12 Oct 2026
Quality tradeoff: The bundled 8 kHz diphone voice is described as a sample voice, and the README notes it is less computationally expensive but more robotic than other voice technology in Flite. · github.com, 12 Oct 2026
Resource limits: For standard diphone voices, the README estimates maximum run-time memory at less than twice the memory needed for the generated waveform, or under 1 MB on 32-bit architectures. · github.com, 12 Oct 2026
Security: The README warns that command-line feature-setting options are debug facilities and malicious values can stop Flite from working, so they are not intended for standard users. · github.com, 12 Oct 2026
Thread safety: The README describes Flite as thread safe, with the release notes specifying thread safety after initialization. · github.com, 12 Oct 2026
Use cases: It is designed for small devices such as phones and PDAs, as well as large servers that need to serve many ports. · github.com, 12 Oct 2026
Voices: The distribution includes one 8K diphone voice, a pruned lexicon, and US English models; additional voices can be downloaded or loaded from files or an HTTP connection. · github.com, 12 Oct 2026

Where Flite stands on Freedom251

Text-to-Speech Software#23 of 223
Text-to-speech tools#109 of 232