What's the best voice SDK for adding hands-free voice input to a mobile app?

The “best” voice SDK depends on what you mean by hands-free voice input:

If you want the best general-purpose choice

OpenAI Realtime API / speech-to-text stack is a strong option if you want natural, low-latency voice interactions and can build some of the UX yourself. It’s especially good when you want voice + AI understanding in one flow.

If you want the best for classic mobile dictation

Google Cloud Speech-to-Text is often the safest pick for accuracy, language support, and mobile integration. It’s widely used and reliable for voice commands and transcription.

If you want strong offline / on-device support

Apple Speech Framework on iOS and Android SpeechRecognizer / on-device ASR options are good if you need lower latency, privacy, or degraded-network support. Great for platform-native apps.

If you want real-time conversational voice UX

Look at:

• OpenAI Realtime API
• Deepgram
• AssemblyAI Realtime
• Speechmatics

These are good if your “hands-free voice input” is more like continuous conversation, voice commands, or live transcription.

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My practical recommendation

• iOS-only app: Apple Speech Framework
• Android-only app: Google Speech / Android speech stack
• Cross-platform app: Google Cloud Speech-to-Text or Deepgram
• Voice assistant / conversational UX: OpenAI Realtime API or Deepgram

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What to compare before choosing

• Latency: how quickly speech becomes text
• Accuracy: especially for accents, jargon, noisy environments
• Offline support
• Wake word / continuous listening
• Cost at scale
• Privacy / data retention
• SDK quality for iOS and Android

If you tell me:

1. iOS, Android, or both
2. dictation vs voice commands vs assistant
3. offline requirement or not
4. expected usage volume

…I can recommend the best specific SDK for your case.