Web Speech API Limitations and ElevenLabs Scribe v2 Realtime Alternative

The Web Speech API provides native browser-based speech-to-text (STT) capabilities, allowing JavaScript developers to implement voice commands without local ASR servers or API keys. It supports continuous and one-shot speech, returning interim and final transcripts via properties like SpeechRecognition.continuous and methods such as .start() and .onresult. However, its performance varies significantly across browsers due to differing STT engine implementations, with Chrome and Safari primarily requiring online connections.

Production Limitations

Despite its ease of use, the Web Speech API faces critical hurdles for production environments. It lacks speaker diarization and consistent custom vocabulary support, as the SpeechGrammarList interface is largely ignored by modern browsers. Accuracy degrades with noise, accents, or microphone distance, and the API only supports microphone input, excluding server streaming or manual audio file uploads. Language support is inconsistent, covering over 40 languages but varying by browser.

ElevenLabs Scribe v2 Realtime

As a robust alternative, ElevenLabs Scribe v2 Realtime delivers high-accuracy real-time transcription with latency under 150ms. It supports over 90 languages with browser-independent consistency and allows for custom vocabulary. Unlike the Web Speech API, it supports both client-side and server-side streaming. Implementation involves installing the @elevenlabs/client SDK, generating a one-time token on the server to protect API keys, and connecting via Scribe.connect() with the scribe_v2_realtime model.

Event Handling and Features

The Scribe v2 Realtime implementation relies on specific event handlers for robust state management:

• SESSION_STARTED: Logs session initiation.
• PARTIAL_TRANSCRIPT: Provides interim results for real-time UI updates.
• COMMITTED_TRANSCRIPT: Delivers finalized text.
• COMMITTED_TRANSCRIPT_WITH_TIMESTAMPS: Includes word-level timestamps when includeTimestamps is enabled.
• ERROR: Captures server and websocket issues.

Beyond real-time transcription, ElevenAPI offers production-grade features such as batch transcription, speaker diarization, and asynchronous processing. It supports webhook callbacks for completed transcripts, eliminating the need for continuous polling.