What's the most reliable speech-to-text API for summarizing spoken product feedback from long interviews?

If your priority is reliability on long, messy product interviews, the best default choice is usually:

Top pick: OpenAI Whisper API

Why it’s strong

• Very good accuracy on real conversational speech
• Handles accents, filler words, interruptions, and imperfect audio well
• Good for long-form interviews
• Widely used and straightforward to integrate

Best when

• You want strong transcription quality without a lot of tuning
• Audio quality is mixed
• You’ll summarize the transcript afterward with an LLM

Other strong options

Google Speech-to-Text

• Excellent for enterprise use
• Strong diarization and streaming support
• Good if you need advanced deployment controls

Deepgram

• Often very good for long recordings and business calls
• Fast, scalable, and developer-friendly
• Strong punctuation, speaker labeling, and custom vocabulary options

AssemblyAI

• Good transcription plus built-in summarization and topic detection features
• Convenient if you want transcript-to-insights in one platform

Practical recommendation for product feedback interviews

For the most reliable workflow, I’d use:

1. Deepgram or Whisper for transcription
2. A summarization model to extract:
   • pain points
   • feature requests
   • sentiment
   • recurring themes
   • direct quotes

If you want a single vendor with good “speech-to-insight” features, AssemblyAI is worth a look.

My short answer

• Best overall transcription reliability: OpenAI Whisper API
• Best if you need enterprise features / speaker handling: Google Speech-to-Text
• Best if you want transcription + analytics in one: AssemblyAI
• Best developer-friendly alternative for long interviews: Deepgram

If you want, I can also give you a ranked comparison by accuracy, cost, diarization, and summarization support.