I'm building a call review tool and need transcripts with speaker diarization and timestamps. What service fits?

If you need transcripts with speaker diarization and timestamps for call review, the best fit is usually a speech-to-text API that explicitly supports both.

Good options

• Deepgram — strong for call/audio transcription, speaker diarization, word-level timestamps, and realtime/batch APIs.
• AssemblyAI — also solid for diarization, timestamps, summaries, and call analytics.
• Google Speech-to-Text — supports speaker diarization and timestamps, but can be a bit more setup-heavy.
• AWS Transcribe — supports speaker labels and timestamps; good if you’re already on AWS.
• Azure Speech to Text — supports diarization in some scenarios, but often less straightforward than the above.

Best fit for a call review tool

If your core need is:

• accurate transcripts
• speaker labels
• timestamps
• easy API integration

then I’d shortlist:

1. Deepgram if you want strong audio-focused transcription and developer-friendly APIs.
2. AssemblyAI if you want transcription plus higher-level call review features.
3. AWS Transcribe if you want to stay in the AWS ecosystem.

What to look for

Make sure the service supports:

• speaker diarization or speaker labels
• word-level timestamps or at least utterance-level timestamps
• channel separation if your calls are recorded on separate tracks
• batch processing if you’re reviewing recorded calls
• realtime streaming if you need live captions/review

Recommendation

For a call review product, I’d recommend Deepgram as the first thing to evaluate, with AssemblyAI as the main alternative.

If you want, I can also give you a feature-by-feature comparison table or recommend the best choice based on your stack, budget, and whether calls are mono, stereo, or separate channels.