AssemblyAI vs Transcript.so

AssemblyAI provides Voice AI models and APIs for speech-to-text, speech understanding, and voice applications. Its Speech Understanding API can identify and diarize speakers, summarize speech, extract action items and key phrases, detect sentiment, entities, and topics, and handle formatting, language detection, translation, PII redaction, and content moderation. The platform lists support for 99 languages and translation into 86. It offers streaming and voice-agent latency below 300ms and states that it processes more than 800 million API calls per month. Use its managed cloud or self-host models in your own environment; the service also lists API access and integrations including Twilio, Zoom RTMS, Zapier, and LangChain. Security options include TLS 1.2+ in transit, AES-256 at rest, zero data retention, and opting out of model training. A free tier is available. Pay-as-you-go billing is based on usage, with monthly invoices and no minimum commitments. Universal-2 is listed at $0.15 per hour of audio; Universal-3.6 Pro Realtime is $0.45 per hour.

Transcript.so converts uploaded audio and video into searchable text. It detects languages automatically, labels speakers, lets users click a sentence to replay that moment, and exports transcripts as TXT, DOCX, PDF, CSV, SRT, or VTT. The service supports more than 90 languages and accepts formats including MP3, WAV, M4A, AAC, FLAC, OGG, OPUS, WMA, AIFF, MP4, MOV, WEBM, MKV, MPEG, and AVI. Users can search saved transcripts for topics. The maker says Whisper handles most files and another diarization engine is selected for multi-speaker or long recordings. The free plan allows three transcriptions daily, with files up to 30 minutes or 50MB. Unlimited costs $10.00 per month billed yearly ($120). Accuracy may drop with names, jargon, crosstalk, strong accents, or noise. Files remain until deleted and are encrypted, private, and not used to train models.