Supertonic 3 Supported Languages and Language Codes: Complete Guide

Supertonic 3 supports 31 individual languages plus a language-agnostic mode using ISO-639-1 two-letter codes passed via the lang parameter across all official bindings.

The supertone-inc/supertonic repository provides a multilingual Text-to-Speech (TTS) engine capable of synthesizing speech from text in 31 distinct languages. Understanding how to specify language codes correctly is essential for optimal voice generation across the various language bindings including Python, JavaScript, Rust, Go, C++, Swift, and C#.

Supported Languages in Supertonic 3

Supertonic 3 synthesizes speech using ISO-639-1 two-letter codes to identify target languages. The system supports 31 individual languages plus a special language-agnostic mode that lets the model infer the language automatically.

The complete list of supported language codes includes:

Code	Language
en	English
ko	Korean
ja	Japanese
ar	Arabic
bg	Bulgarian
cs	Czech
da	Danish
de	German
el	Greek
es	Spanish
et	Estonian
fi	Finnish
fr	French
hi	Hindi
hr	Croatian
hu	Hungarian
id	Indonesian
it	Italian
lt	Lithuanian
lv	Latvian
nl	Dutch
pl	Polish
pt	Portuguese
ro	Romanian
ru	Russian
sk	Slovak
sl	Slovenian
sv	Swedish
tr	Turkish
uk	Ukrainian
vi	Vietnamese
na	Language-agnostic

Use the special na code when you want Supertonic to automatically detect and infer the language from the input text.

Where Language Codes Are Defined in the Source

According to the Supertonic source code, each language binding maintains an identical canonical list of available languages in helper validation files. These constants ensure consistent behavior across platforms:

• JavaScript/Web: web/helper.js exports AVAILABLE_LANGS as an array of strings
• Python: py/helper.py defines AVAILABLE_LANGS as a list constant
• Rust: rust/src/helper.rs declares pub const AVAILABLE_LANGS: &[&str]
• Swift: swift/Sources/Helper.swift contains let AVAILABLE_LANGS
• Go: go/helper.go specifies const AVAILABLE_LANGS
• C++: cpp/helper.cpp uses const std::vector<std::string> AVAILABLE_LANGS
• C#: csharp/Helper.cs references Languages.Available

If an unsupported code is supplied, these helpers throw language-specific errors indicating the valid set.

How to Specify Language Codes in Each Binding

Each binding exposes a parameter—commonly named lang, --lang, or language—that accepts one of the ISO-639-1 codes above.

JavaScript and Web

In web/helper.js, pass the language code via the lang property:

import { synthesize } from "./helper.js";

const wav = await synthesize({
  text: "Hello, world!",
  voice: "en_female_1",
  lang: "en",
  nfe: 5,
});

The helper validates that "en" exists in AVAILABLE_LANGS before processing.

Python

The Python binding in py/helper.py uses a lang parameter and raises ValueError for invalid codes:

from supertonic.helper import synthesize

wav = synthesize(
    text="Bonjour le monde!",
    voice="fr_male_2",
    lang="fr",
    nfe=5,
)

Rust CLI

For the Rust command-line interface defined in rust/src/helper.rs, use the --lang flag:

supertonic-cli \
  --text "こんにちは世界" \
  --voice ja_female_1 \
  --lang ja \
  --nfe 5 \
  --output hello.wav

The binary aborts with a clear error if the code is not found in AVAILABLE_LANGS.

Go

In go/helper.go, specify the language via the Lang field:

wav, err := helper.Synthesize(helper.Params{
    Text:  "Привет мир",
    Voice: "ru_male_1",
    Lang:  "ru",
    NFE:   5,
})

Invalid codes trigger a panic listing available languages.

C++

The C++ implementation in cpp/helper.cpp validates codes against AVAILABLE_LANGS and throws std::runtime_error on mismatch:

auto wav = synthesize(
    "Hallo Welt",
    "de_female_1",
    "de",
    5
);

Swift

For iOS development using swift/Sources/Helper.swift, use the language parameter:

let wav = try Helper.synthesize(
    text: "안녕하세요",
    voice: "ko_female_1",
    language: "ko",
    nfe: 5
)

An invalid code results in a fatalError displaying the full valid list.

C#

In the C# binding (csharp/Helper.cs), pass the code via the lang parameter:

var wav = Helper.Synthesize(
    text: "Ciao mondo",
    voice: "it_male_1",
    lang: "it",
    nfe: 5);

Helper.cs validates against Languages.Available and throws ArgumentException for unsupported codes.

Summary

• Supertonic 3 supports 31 languages using ISO-639-1 two-letter codes plus a language-agnostic mode (na)
• Language validation is enforced consistently across all bindings via AVAILABLE_LANGS constants in helper files
• Specify codes using the lang, --lang, or language parameter depending on your binding
• Invalid codes trigger immediate errors with helpful messages listing supported options
• Use na (language-agnostic) when you want Supertonic to infer the language automatically

Frequently Asked Questions

What happens if I use an unsupported language code in Supertonic 3?

Each binding validates input against the AVAILABLE_LANGS constant. If you provide an unsupported code, the library throws a language-specific error: ValueError in Python, std::runtime_error in C++, ArgumentException in C#, or a panic in Go and Rust. All error messages include the complete list of valid codes.

Can I use Supertonic 3 without specifying a language?

Yes. Pass the special code na (language-agnostic) to let Supertonic automatically infer the language from your input text. This is useful when processing multilingual content or when the source language is unknown.

Are language codes case-sensitive in Supertonic 3?

The source code stores language codes as lowercase strings in all AVAILABLE_LANGS arrays. While some bindings may normalize input, you should use lowercase ISO-639-1 codes (e.g., "en" not "EN") to ensure compatibility across all platforms.

How do I check if my language is supported programmatically?

Access the public AVAILABLE_LANGS constant exposed in each binding's helper file. For example, in Python import AVAILABLE_LANGS from supertonic.helper, or in JavaScript import { AVAILABLE_LANGS } from ./helper.js. Check if your desired code exists in this array before calling synthesize.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}