AssemblyAI

AssemblyAI is an AI API for speech-to-text with speaker labels, summaries, and content moderation. Developers send audio to the API and get back a transcript with diarization, sentiment analysis, entity detection, and summaries, all in one call. It is built for apps that need more than raw text from their audio.

Key Features

Speech-to-text API with high accuracy
Speaker diarization and summaries
Sentiment analysis and entity detection
Content moderation built in
Pay-as-you-go by the audio hour
99 languages supported

Pricing

Plan	Price	Details
Free Credit	$0	$50 in free credits, no card required; covers up to 333 hours of Universal-2.
Universal-2	$0.15/hr	Pre-recorded transcription, billed per audio hour.
Universal-3.5 Pro	$0.21/hr	Higher-accuracy pre-recorded transcription, billed per audio hour.

Prices as listed in 2026 research. Always check the official site for the latest price — plans change. Free plan: Yes — it has a free plan.

Best for: developers who need accurate speech-to-text with speaker labels, summaries, and moderation.
Popular with: Developers, Business Owners

How it works

Pricing is pay-as-you-go by the audio hour: the Universal-2 model costs $0.15 an hour and Universal-3.5 Pro costs $0.21 an hour for pre-recorded audio, with streaming from $0.15 an hour. A $50 free credit lets you transcribe hundreds of hours before paying, with no credit card required.

AssemblyAI is a strong choice for developers building transcription into a product, a call analytics tool, or a content moderation pipeline. The API is well documented and the models are accurate across 99 languages. If you just need a transcript of one file, a consumer tool is simpler, but for building on top of speech AI, AssemblyAI is one of the best APIs available.

Key Features

Pricing

How it works

Pros and Cons

✓ Pros

✗ Cons

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