What is AssemblyAI?
AssemblyAI is a voice AI platform that provides speech-to-text, speech understanding, and voice agent APIs for developers building voice features into products on any stack. AssemblyAI differentiates itself by combining pre-recorded, real-time, and synchronous transcription models with speech understanding, guardrails, an LLM gateway, and a self-hosted voice AI cloud in a single platform.
Key Features
- Pre-recorded Speech-to-Text API: Transcribes uploaded audio files with the Universal-3.5 Pro speech model, suited to batch transcription workloads such as call recordings and media archives.
- Realtime Speech-to-Text API: Streams transcripts as audio arrives, using a streaming client that emits turn events with transcript text and end-of-turn flags, which supports live voice interfaces.
- Sync Speech-to-Text API: Handles short audio clips within a synchronous request flow, useful when an application needs a transcript returned immediately.
- Speech Understanding API: Extracts meaning from transcribed speech rather than returning text alone, so developers can build analysis on top of audio.
- Voice Agent API: Provides the speech infrastructure for building voice agents that listen and respond within a product.
- Dictation API: Returns text that is ready to send, removing filler words, resolving self-corrections, and spelling names correctly, which is designed specifically for dictation interfaces.
- Guardrails and Safety plus LLM Gateway: Adds safety controls and a gateway layer for routing model calls alongside the speech APIs.
- Self Hosted Voice AI Cloud: Offers an inference deployment option for teams that need to run voice AI infrastructure in their own environment.
- Language coverage: Supports 99 languages, including English, Spanish, Portuguese, French, German, Russian, Hindi, Dutch, Japanese, and Italian.
Use Cases
- Voice agents: Teams building conversational voice interfaces can combine the Realtime Speech-to-Text API with the Voice Agent API to handle live spoken input and responses.
- AI notetakers and AI scribes: Products that record meetings or sessions can use the Pre-recorded Speech-to-Text API and Speech Understanding API to produce transcripts and extract content from them.
- Call analytics: Call centers and analytics teams can transcribe recorded calls and apply speech understanding to analyze what was said.
- Medical transcription: Healthcare documentation workflows can use transcription APIs to convert spoken clinical notes into text.
- Dictation: Applications that let users speak instead of type can use the Dictation API to return cleaned-up text with fillers removed and names spelled correctly.
- Agent assist: Support and sales teams can transcribe live or recorded interactions to assist agents during or after calls.
Who It Is For
AssemblyAI is aimed at developers and engineering teams who need to add speech capabilities to a product without building speech models themselves. That includes teams working on voice agents, notetaking apps, call analytics platforms, medical transcription, dictation features, and agent assist tools. The platform serves developers across any stack through APIs, and its self-hosted inference option addresses teams with infrastructure requirements beyond a hosted API.
Pricing
AssemblyAI offers a free sign-up option and a contact sales path for larger engagements. Specific pricing figures are not stated in the source material.
Frequently Asked Questions
What is AssemblyAI used for?
AssemblyAI is used to transcribe speech to text and to understand what was said in that speech. Developers use AssemblyAI to build voice agents, AI notetakers, call analytics, medical transcription, dictation, and agent assist features into their products.
What APIs does AssemblyAI offer?
AssemblyAI offers pre-recorded, realtime, and sync Speech-to-Text APIs, a Speech Understanding API, a Voice Agent API, and a Dictation API. The platform also includes Guardrails and Safety, an LLM Gateway, and a Self Hosted Voice AI Cloud, with a Text-to-Speech API listed as coming soon.
How many languages does AssemblyAI support?
AssemblyAI supports 99 languages. Named examples include English, Spanish, Portuguese, French, German, Russian, Hindi, Dutch, Japanese, and Italian.
Is AssemblyAI free?
AssemblyAI offers a free sign-up option on its website. Pricing details beyond that are not specified in the source material, and a contact sales route is available for further discussion.
Who should use AssemblyAI?
AssemblyAI is intended for developers and engineering teams adding speech features to products, such as voice agents, notetakers, call analytics, medical transcription, and dictation tools. Teams that need to run voice AI inference in their own environment can use the Self Hosted Voice AI Cloud option.
