AssemblyAI

AI speech-to-text API with built-in audio intelligence features for developers.

Pricing Free tier (up to 185 hrs pre-recorded) / Pay-as-you-go from $0.15/hr (Universal-2) or $0.21/hr (Universal-3.5 Pro) / Streaming from $0.15/hr

Category Transcription

Quick take

AssemblyAI is the best choice when you need more than transcription. LLM Gateway turns a speech-to-text API into a conversation understanding platform. On pre-recorded price, Universal-2 now undercuts Deepgram Nova-3. For transcription plus intelligence, AssemblyAI wins. Many teams end up using both: Deepgram for real-time streaming and AssemblyAI for post-call analysis.

AssemblyAI scorecard

How we grade

A- 83/100

Overall grade

Speech API with the deepest audio intelligence toolkit.

Idea A- Transcription plus audio intelligence and LLM Q and A is a strong angle.

Brand B+ Well regarded developer speech-AI brand.

Product A- Rich intelligence features and LLM Gateway stand out.

Market fit B+ Fits developers needing more than raw transcripts.

Adoption B+ Good dev traction, no g2 provided here.

Features A- Sentiment, entities, PII redaction, streaming, LLM Gateway.

Security B+ PII redaction signals strong data handling.

Value B Universal-2 from $0.15/hr with streaming; premium models cost more.

Overview

AssemblyAI is a speech-to-text API that competes directly with Deepgram but differentiates with LLM-powered post-processing features. Beyond basic transcription, AssemblyAI offers LLM Gateway, formerly LeMUR (a way to apply large language models to transcripts), which enables summarization, question answering, action item extraction, and custom prompts. The company has raised significant funding and focuses exclusively on the developer API market, not consumer products.

Strengths & limitations

Strengths

+Rich audio intelligence features beyond transcription
+LLM Gateway enables Q&A on audio content
+Excellent developer documentation
+Universal-2 at $0.15/hr undercuts Deepgram Nova-3 pre-recorded ($0.0043/min, about $0.26/hr)

Limitations

–Universal-3.5 Pro covers 18 languages, fewer than Universal-2's 99
–Premium real-time model (Universal-3.6 Pro Realtime) costs $0.45/hr
–In-region US/EU processing costs 10% more

Pricing

Free tier (up to 185 hrs pre-recorded)Pay-as-you-go from $0.15hr (Universal-2) or $0.21hr (Universal-3.5 Pro)Streaming from $0.15hr

Pay As You Go: pre-recorded transcription from $0.15/hour (Universal-2, 99 languages) or $0.21/hour (Universal-3.5 Pro). Streaming from $0.15/hour (Universal-Streaming), with Universal-3.6 Pro Realtime at $0.45/hour. Speaker diarization adds $0.02/hour. In-region US or EU processing is 10% higher. LLM Gateway usage is billed per token. The free tier covers up to 185 hours of pre-recorded or 333 hours of streaming transcription. Enterprise plans with custom pricing and a self-hosted option.

Who it's for

Developers who need transcription plus LLM-powered intelligence in one API. Teams building meeting summarization, coaching, or compliance features who want to avoid wiring together a separate transcription service and LLM. If you only need raw pre-recorded transcription and care about cost, compare Universal-2 ($0.15/hour) with Deepgram Nova-3 ($0.0043/min). If you want the intelligence layer built in, AssemblyAI saves development time.