IBM Watson

The IBM Speech to Text service provides a Representational State Transfer (REST) Application Programming Interface (API) that enables you to add IBM's speech transcription capabilities to your applications. The service also supports an asynchronous HTTP interface for transcribing audio via non-blocking calls. And it supports a beta language model customization interface that lets you expand the base vocabulary of a US English or Japanese language model with domain-specific terminology.

The service transcribes speech from various languages and audio formats to text with low latency. The service supports transcription of the following languages: Brazilian Portuguese, French, Japanese, Mandarin Chinese, Modern Standard Arabic, Spanish, UK English, and US English. For most languages, the service supports two sampling rates, broadband and narrowband.