I’m looking for an audio transcription API that can handle accents, custom vocabulary, and webhooks. What should I evaluate?

When evaluating an audio transcription API for accents, custom vocabulary, and webhooks, I’d look at these areas:

1) Accuracy on real-world speech

• Accent robustness: Test with the specific accents you care about, not just “standard” speech.
• Domain vocabulary: Check how well it handles product names, jargon, acronyms, names, and code-switching.
• Background noise / overlap: Measure performance in noisy environments, on calls, or with multiple speakers.
• Punctuation and formatting quality: Useful if transcripts need to be readable or searchable.

2) Custom vocabulary support

Look for:

• Custom word lists / phrase hints / boost terms
• Phrase weighting or confidence boosting for key terms
• Automatic updating of vocabularies per tenant/customer/project
• Limits: max words, max characters, supported languages, and whether custom terms expire
• Whether it supports proper nouns, acronyms, and phonetic spellings

3) Webhook/event handling

Make sure the API supports:

• Asynchronous jobs with completion webhooks
• Retry behavior for failed webhook deliveries
• Event types beyond “done” (started, progress, failed, partial, diarization complete, etc.)
• Payload contents: transcript text, word timestamps, confidence, speaker labels, error details
• Security: signed webhooks, secret rotation, IP allowlisting, idempotency
• Ordering guarantees if partial results matter

4) Timing and features

• Streaming vs batch transcription
• Latency to first partial result and final transcript
• Word-level timestamps
• Speaker diarization if calls or meetings matter
• Language identification and multilingual support
• Real-time transcription quality under low latency

5) Integration and developer experience

• Simple REST/SDKs
• Clear error codes
• Ability to store/retrieve transcripts
• Support for common audio formats and sample rates
• Good docs, examples, and sandbox/testing tools

6) Security and compliance

• Data retention controls
• Encryption in transit and at rest
• SOC 2, ISO 27001, HIPAA, GDPR, or other requirements relevant to you
• Region/data residency options
• Whether audio is used for model training, and if you can opt out

7) Cost and operational fit

• Pricing by minute, feature tier, or model
• Extra charges for custom vocabulary, diarization, or streaming
• Throughput limits, concurrency caps, rate limits
• Reliability/SLA and support responsiveness

8) How to compare vendors

Use a small benchmark set:

• 30–100 clips covering your real accents, vocabulary, noise levels, and audio quality
• Score:
  • Word error rate (WER)
  • Term accuracy for custom vocabulary
  • Latency
  • Webhook reliability
  • Total cost

If you want, I can also give you:

1. a vendor evaluation checklist, or
2. a comparison table of popular transcription APIs.