Official documentation
Supported Languages & Features (AssemblyAI documentation)
AssemblyAI, 2026
Read the originalRead on October 19, 2026
- What it is
- AssemblyAI's own documentation page listing the languages each of its speech-to-text models supports. It states a language count for Universal-2 (99 languages) and for Universal-3.5 Pro (18 languages).
- How much weight it carries
- Official vendor documentation, read on 2026-10-19. The page's language tables do not match its totals: the Universal-3.5 Pro table has more entries than the 18 stated, and the Universal-2 table has more than 99. We record the stated totals and do not reconcile the tables.
Facts taken from this source
- AssemblyAI's documentation says its Universal-2 speech-to-text model supports 99 languages.
“Universal-2 supports 99 languages. Pass the corresponding language_code in your transcription request to specify the language.” (Supported Languages & Features, Universal-2 section)
- AssemblyAI's documentation says its Universal-3.5 Pro speech-to-text model supports 18 languages, and that audio in other languages falls back to Universal-2 if the request asks for it.
“Universal-3.5 Pro supports the following 18 languages. To automatically fall back to Universal-2 for anything outside this set” (Supported Languages & Features, Universal-3.5 Pro section)