Overview
AssemblyAI offers Speech AI models via an API that product teams and developers can use to build powerful AI solutions based on voice data. Thousands of developers build on AssemblyAI's Speech AI models every day to run Speech-to-Text on multilingual speech, and harness the power of Large Language Models to extract the full value from that voice data - including answering questions from voice data, generating content, and extracting metadata in seconds. AssemblyAI offers two of the world's most powerful and accurate async transcription models, as well as real-time transcription with ultra high accuracy, low latency, and built-in turn detection.
AssemblyAI gives you access to state-of-the-art Speech AI models and capabilities for real-world use cases with unlimited concurrency and no upfront contract commitment, so you can build smarter applications in a fraction of the time. Models and features include:
- Speech recognition
- Keyterms prompting for streaming
- Auto language detection
- Translation
- Speaker diarization and identification
- Auto punctuation and casing
- Custom formatting
- Custom spelling
- Custom vocabulary
- Guardrails, including Content Moderation, PII Redaction, and Profanity Filtering
- Filler word filtering
- Summarization
- Sentiment analysis
- Auto highlights
- Topic detection (IAB classification)
- Entity detection
- Auto chapters
- Dual channel transcription
- Export SRT or VTT caption files
In addition, LLM Gateway allows you to connect speech-to-text outputs directly to your preferred leading LLM provider through a single, unified API for tasks like output fine-tuning, summarization, question & answer, and AI coaching feedback.
Our Speech AI products support 33 different audio and video file types and 99+ languages. Our models are used by thousands of breakthrough startups and dozens of global enterprises for mission-critical workloads.
Highlights
- Unparalleled Human-Level Accuracy: Our multilingual speech recognition AI models deliver industry-leading performance with the lowest word error rates on the market, outperforming competitors by over 60% when recognizing challenging content like rare words and proper nouns. Trusted by more than 3,000 innovative companies, including Zoom, our platform provides the foundation for mission-critical speech applications at scale.
- Built for enterprise-grade performance, our APIs deliver unmatched scalability for high-concurrency applications. Security is embedded with SOC 2 Type 2, PCI DSS, and GDPR compliance. For healthcare applications, AssemblyAI offers Business Associate Agreements (BAAs). Choose flexible hosting options in both US and EU regions.
- Comprehensive Speech Understanding Suite and Guardrails: Our advanced models summarize conversations, identify speakers through diarization, analyze sentiment, moderate content, automatically redact PII, and much more, all in a single platform. Our LLM Gateway seamlessly connects spoken data with your preferred large language models, enabling unlimited possibilities for voice-powered applications in one unified platform.
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Pricing
Dimension | Description | Cost/unit |
|---|---|---|
Universal-2 | Fast, intelligent async transcription with exceptional accuracy and unlimited concurrency | $0.15 |
SLAM-1 (deprecated) | Highest accuracy transcription powered by LLM intelligence | $0.27 |
Universal Streaming | Fast, accurate real-time transcription. Built-in turn detection and unlimited concurrency | $0.15 |
Keyterms Prompting (Universal Streaming) | Improve recognition accuracy for specific words and phrases | $0.04 |
Speaker Identification | Identify speakers by their actual names and roles | $0.02 |
Translation | Automatically convert your transcribed audio content from one language to another | $0.06 |
Custom Formatting | Ensure consistency through automatic, standardized formatting | $0.03 |
Entity Detection | Identify entities like person and company names, email addresses, dates, and locations | $0.08 |
Sentiment Analysis | Detect the sentiment of each sentence of speech spoken in your audio files | $0.02 |
Auto Chapters | Automatically generate a summary over time for audio and video files | $0.08 |
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All fees are non-refundable and non-cancellable except as required by law.
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Support is available 24/7 via chat on our website at <www.assemblyai.com > or email at support@assemblyai.com .
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Customer reviews
Story workflows have become faster as automated summaries and voices keep readers engaged
What is our primary use case?
My main use case for AssemblyAI is to summarize content. Our company asks writers to write complete applications, tell complete stories, or narrate stories on our platform. By using AssemblyAI , we create text-to-speech and textual summarization features. Writers accumulate their work into scripts or summaries, and we use those summaries to produce novel summaries.
A specific example of how I use AssemblyAI in my workflow is that story writers write complete stories, and AssemblyAI summarizes the entire story so that readers can access the summary written by the authors. Additionally, we have used it for text-to-speech, and we have utilized AssemblyAI in our workflow for both of these cases.
What is most valuable?
The best features AssemblyAI offers are summarization and animations. The AI summarization feature stands out for me because we work with Pocket FM, and we utilize it for summarization of our novelists and novel writers' stories. We have also utilized AssemblyAI for different voice generation options.
AssemblyAI has positively impacted my organization because by using it, both our story narrators and story readers benefit greatly. We are able to successfully generate better summaries of stories and story chapters, and the text-to-voice feature is very helpful for our users.
Specific outcomes that show how AssemblyAI has helped my organization include increased engagement and positive user feedback for text-to-speech. User engagement has increased from 76% to 78% by using AssemblyAI.
What needs improvement?
One area where AssemblyAI can be improved is in summarization. Sometimes it does not fetch the correct words or identify the most important things for that chapter, so it needs to improve in this area.
For how long have I used the solution?
I have been using AssemblyAI for two years.
What do I think about the stability of the solution?
AssemblyAI is stable in my experience.
What do I think about the scalability of the solution?
The scalability of AssemblyAI for my organization is good as we have a high volume of scale right now, with around 25,000 requests, and it is performing well.
How are customer service and support?
For customer support of AssemblyAI, I would rate it six to seven because sometimes they help us in a great way, but sometimes they do not help or take a long amount of time. AssemblyAI has a chatbot that helps a lot and assists us in accomplishing tasks, so I am satisfied with it.
Which solution did I use previously and why did I switch?
Before using AssemblyAI, I previously utilized ChatGPT for summarization of text and chapters written by authors. This process took a large amount of time, which led us to switch to AssemblyAI.
How was the initial setup?
On a scale of ten, I rate how easy it was to implement AssemblyAI in my environment as eight.
What about the implementation team?
I integrate AssemblyAI with my existing systems and workflows by using the Python library.
For updates or maintenance of AssemblyAI in my setup, the updates do not come frequently, so whenever they come, we update the Python package library.
What was our ROI?
I have seen a return on investment from AssemblyAI through time saving. Before using other tools for summarization of writers' stories, it took a lot of time, but with AssemblyAI, the time to convert a story into a summary has decreased significantly.
What's my experience with pricing, setup cost, and licensing?
Regarding my experience with pricing, setup cost, and licensing, I would like to know if it can be reduced somehow, but apart from that, licensing is good enough for us.
Which other solutions did I evaluate?
I did not evaluate other options before choosing AssemblyAI because I was referred to this platform by one of my seniors, so I utilized it directly and am happy with this software.
What other advice do I have?
My advice for others looking into using AssemblyAI is to check the packages in different languages while integrating it into their use cases, so I recommend checking those availability options. I would rate this review overall as an eight.
Building an in-house voice chatbot has reduced costs and creates faster speech-to-text workflows
What is our primary use case?
I used AssemblyAI for a small task in my company where I had to create a chatbot, and my work was mostly converting speech to text.
My main use case for AssemblyAI was to create a voice-to-voice interactive chatbot. For the task of converting speech to text, I used AssemblyAI's API, which was quite good, with the best latency and a very good experience overall.
A specific example of how I used AssemblyAI in my chatbot project was in the pipeline that initially converted speech to text, then sent that text to an LLM for a response, then converted it back to speech again, sending it to the client's browser. I focused mainly on the speech-to-text conversion, which required AssemblyAI.
What is most valuable?
What stood out to me about the speech-to-text feature of AssemblyAI was the speed, accuracy, and ease of integration. All of these strong points contributed to a very good development experience while working with AssemblyAI.
AssemblyAI positively impacted my organization as we previously used Vapi for all voice-related chatbot tasks. Since I created the in-house chatbot using AssemblyAI and LLMs, our product became much cheaper, and we no longer need to rely on Vapi or Retell.
The main outcome since switching to AssemblyAI was cost savings. Although I cannot recall the exact amount we saved, I know we saved a fair amount using our chatbot.
What needs improvement?
I believe AssemblyAI needs to improve its filter for removing filler words. It works quite well and automatically removes terms such as 'um' and detects when I stop talking, so I think it is already up to the mark with latency and performance.
I wish AssemblyAI could improve its multilingual support, as it did not work well when I spoke in different languages. For instance, it works better in English than in Hindi or other languages.
No improvements are needed for AssemblyAI beyond the multilingual support I mentioned, as everything else seems quite good.
For how long have I used the solution?
I have been working in my current field as an intern from January 2025 through April 2025.
What other advice do I have?
I rate AssemblyAI a 10 because I had a specific use case and found it through a Google search by typing 'API for converting speech to text'. The experience I had integrating it was very easy, and I had no difficulties integrating AssemblyAI with my project. The output was excellent.
Regarding AssemblyAI's AI capabilities, I think the accuracy and reliability of output are up to the mark. Since I already gave it a 10, you can assume all my answers are positive.
If someone comes to me trying to build a chatbot, I recommend using AssemblyAI for the speech-to-text task. My recommendation alone carries weight.
I appreciate that AssemblyAI had a very good developer experience, although I do not remember all the specifics since it was a long time ago.
My overall review rating for AssemblyAI is 10.
Which deployment model are you using for this solution?
If public cloud, private cloud, or hybrid cloud, which cloud provider do you use?
Reliable transcripts have boosted client trust and now save hours on every project
What is our primary use case?
AssemblyAI serves as my primary tool for transcription processes. Whenever discussions are completed, I use it to create transcripts for sessions so that I can deliver errorless files to my clients.
I have a specific case study that demonstrates how I use AssemblyAI in my workflow. I was working on a project that required AI moderation along with transcriptions, and AssemblyAI played a major role in delivering the project. We had interviews completed with our experts, and I needed to create a report and consolidate the data from those interviews. I used AssemblyAI to create a clear and high-quality transcript to share with the client. Using AssemblyAI has worked exceptionally well for me because it has helped my team input very little effort to check for quality. This was a project where AssemblyAI proved to be truly helpful. We complete these types of projects regularly, primarily around three to four projects per month, and every project includes AssemblyAI. I am a big fan of AssemblyAI.
What is most valuable?
The most important feature I appreciate is that once I upload my file, it automatically generates a high-quality transcript by removing all unnecessary words and language-hearing errors, which I cannot obtain from any other software. AssemblyAI pre-qualifies the transcript and already performs a good quality check. Regarding the credibility and accuracy of AssemblyAI, I believe it has excellent accuracy of around ninety-two to ninety-five percent. The remaining five percent still needs work in this area, but ninety-five percent is very good from my perspective.
AssemblyAI has impacted my organization positively by increasing credibility, accuracy, and productivity.
My productivity has improved significantly with substantial time savings. It is faster than when we were transcribing manually. It used to take us around four to five hours to transcribe a single file, but with AssemblyAI, I complete it within an hour, including all quality checks and the entire process. That is a great advantage for me.
What needs improvement?
AssemblyAI needs to be more accurate, particularly with regard to spelling. For example, drug spellings are sometimes very illogical or misspelled, and this can be improved. Healthcare terms, specifically drug terms related to the medical field, drug products, or chemical products, are sometimes misspelled.
For how long have I used the solution?
I have been using AssemblyAI for my transcriptions for over one and a half years.
What other advice do I have?
AssemblyAI's governance and security are very secure to use. I do not have extensive knowledge about governance and security, but overall security is great from AssemblyAI, particularly regarding my files and confidentiality.
I deploy AssemblyAI as my personal choice. I do not know if many people are using it, but I prefer AssemblyAI.
For AssemblyAI, I work only offline with this tool. I do not save my files on the cloud; I simply take the transcript, download it to my computer, and then work accordingly.
I would definitely recommend giving AssemblyAI a chance, and you will appreciate it.
My overall rating for this review is nine out of ten.
Automated workflows have transformed classroom videos into instant interactive study content
What is our primary use case?
My primary use case was establishing a highly reliable video-to-text-to-content pipeline. AssemblyAI acted as the essential bridge between unstructured video data and a structured generative model. During integration, I realized that the quality of the downstream AI-generated formats depended on the accuracy of the initial transcription. If the speech-to-text API missed technical terms, the generated study aids were flawed. Using AssemblyAI ensured the transcript was highly accurate, meaning that the final educational tools generated by our LLM were of professional academic quality. Additionally, handling the asynchronous polling on our back end proved to be highly stable and easy to maintain.
Once my video is uploaded and turned into an MP3, AssemblyAI takes this MP3 file and converts it into text through its speech-to-text capability. This text is then fed into the AI. When the teacher logs into their dashboard, they fill a form with the lesson objectives and upload the MP4 video. As soon as this upload reaches our Node.js back end, I extract the audio and send it to AssemblyAI, which indicates the processing to the users. AssemblyAI works through the technical jargon. Within a minute or two, the teacher receives a notification that the lesson is ready, so they did not have to write the transcript or timestamp their video because AssemblyAI handled all the heavy lifting. For the student workflow, students enrolled in that specific teacher course open the lesson, watch the video, and then want to test their knowledge. Under the video player, they see generated flashcards, quizzes, or other study tools. Our platform does not need to reprocess the video. We take the high-accuracy text transcript already provided by AssemblyAI and feed it into our LLM to instantly generate 10 flashcards based exactly on what the teacher said in the video.
What is most valuable?
The best features AssemblyAI offers based on my integration experience include, first, the high-accuracy core transcription. It has the ability to accurately transcribe complex technical terminology including programming concepts and framework names and handles varying audio quality, such as classroom recordings with background noise, which is exceptional. The built-in file uploading through the /v2/upload endpoint is a huge time-saver for developers. It allowed me to stream audio files directly to their API for temporary hosting, eliminating the need to configure and manage intermediate public cloud storage such as AWS S3 before triggering transcription. The third feature is the precise word-level timestamps. The API returns the exact start and end times of every single word in the transcript. This metadata is essential for building modern e-learning features, such as synchronizing video playback with the transcript text or generating automated closed captions.
The integration of AssemblyAI has had a highly positive impact on my platform in three key areas. The significant faculty time savings means that automating the transcription process saved our instructors hours of manual labor per video. Instead of typing transcripts or drafting summaries, they could rely on the automated system, freeing up their time to focus on course quality and student interaction. The strong competitive advantage enabled us to launch our core adaptive learning feature set, transforming static, passive video lessons into interactive study tools including flashcards, quizzes, worksheets, and quiz games automatically, which sets our platform apart from standard video-only offerings. The last area is the low operational and infrastructure costs. Because AssemblyAI is a cloud-based, pay-as-you-go service, we avoided the high upfront costs of purchasing and maintaining expensive GPU hardware, which allowed us to offer automated study aids across our entire course catalog while keeping our margins highly efficient.
What needs improvement?
While AssemblyAI performs exceptionally well, there are a few areas where the developer experience could be further improved. First, regarding native video file support, currently, developers must write custom back-end logic to extract the audio track from video files locally before uploading. If AssemblyAI supported direct native video uploads and handled the audio extraction internally on their servers, it would simplify our back-end architecture. Native real-time status updates could also be improved because while the API is highly stable, writing custom asynchronous polling loops to check transcription status adds boilerplate code. Lastly, the queue latency for micro-files could be optimized because we noticed some initial queue or warm-up latency when transcribing very short audio files under one minute.
For how long have I used the solution?
I have been working in my current field as a full stack developer and freelancer for nearly one year after I graduated from computer engineering.
What do I think about the stability of the solution?
AssemblyAI proved to be exceptionally stable throughout our development and testing phases. It has a high API uptime; I experienced near-perfect uptime on the public API endpoints. It maintains consistent response times and predictable HTTP status codes, with stable queuing and polling. The asynchronous transcription queue worked exactly as documented, where status transitions from queued to processing to completed never hung or failed silently, which made our Node.js polling logic highly reliable. It has robust connection handling, and we did not experience any connection resets.
What do I think about the scalability of the solution?
AssemblyAI's scalability is excellent and requires zero infrastructure management from the developer because it relies on serverless resource scaling since it is a cloud-native API. It handles the scaling of GPU and CPU resources entirely on their end, so we did not have to worry about provisioning or scaling hardware to handle spikes in concurrent users. Its robust queue management means the asynchronous architecture handles spikes in concurrent transcription, where multiple uploads are placed in a stable queue and processed sequentially without crashing. The API is built to handle enterprise-level volumes, which means we can scale from a small local test environment to thousands of active students without making any changes to our back-end code.
How are customer service and support?
Our experience with AssemblyAI's customer support and developer relations has been highly positive. It has excellent documentation and SDKs, responsive developer channels, and clear API error messages. For example, the API returns detailed, self-explanatory error codes and messages when our requests fail.
How was the initial setup?
Before selecting AssemblyAI, I evaluated several other speech-to-text options, including the OpenAI Whisper API, AWS Transcribe, Google Speech-to-Text cloud, and the self-hosted open-source Whisper.
What was our ROI?
We saw a clear and immediate return on investment, both in terms of operational cost reduction and time saving. There was a 98% cost reduction on transcription because traditional manual human transcription costs a lot, so by using AssemblyAI, the cost dropped significantly. The instructor time saved means that manual transcribing lectures would take a lot of time, so using AssemblyAI saved massive chunks of time. Instant content generation also saved time for the students, so they do not wait for days for a teacher to manually write summaries and flashcards. Our automated pipeline generated study aids within two minutes of a video finishing its processing, dramatically improving the user experience.
What's my experience with pricing, setup cost, and licensing?
Our experience with AssemblyAI's licensing and pricing was highly favorable because it has zero upfront fees. There are no licensing fees, setup costs, or long-term contract requirements. The cost-effective pay-as-you-go model means billing is strictly calculated per minute of audio processed, and the low barrier to entry with initial free promotional credits allowed us to build, integrate, and test our entire audio processing pipeline thoroughly without an upfront financial commitment.
Which other solutions did I evaluate?
Before selecting AssemblyAI, I evaluated several other speech-to-text options, including the OpenAI Whisper API, AWS Transcribe, Google Speech-to-Text cloud, and the self-hosted open-source Whisper.
What other advice do I have?
An additional feature that deserves mention is the Auto Punctuation and Smart Formatting. This was highly valuable for our downstream generative AI pipeline because the transcript returned by AssemblyAI was already formatted as a clean written article. Our LLM, which is Gemini , could parse it easily, resulting in much higher quality generated summaries, quizzes, and flashcards for our students.
For other development teams considering AssemblyAI, I would offer the following advice based on our implementation: first, leverage the direct upload endpoint. During your initial prototyping and development, utilize the /v2/upload endpoint because streaming local files directly to AssemblyAI saved the overhead of configuring cloud storage buckets. Second, use webhooks for production; while writing a simple polling loop is easy for local testing, transition to their webhook notifications for production to save significant CPU and network resources on your back end. Lastly, plan the local media pipeline; if you are transcribing video files, ensure you build a robust and well-logged local audio extraction pipeline using tools such as FFmpeg to strip the audio track first, as this optimizes file transfer size and reduces processing latency.
AssemblyAI is the most effective tool that a developer could use, and I would rate this product a 9 out of 10.
Call analysis has become accurate as speaker identification and English transcription work well
What is our primary use case?
My main use case for AssemblyAI is to transcribe audio using the AssemblyAI API, though I faced some issues with it later on. For general transcribing, it performs well, and I also used the summary and text diarization APIs.
I receive call recordings, apply a transcript to them, and conduct analysis on those call recordings, which is my primary use case with AssemblyAI.
What is most valuable?
One of the best features AssemblyAI offers, in my experience, is that it understands when two people are talking and transcribes those conversations properly, identifying Speaker 1 and Speaker 2 and providing the actual transcript.
The speaker diarization feature works well for my specific use case, especially when I am doing English audio transcription; it handles it pretty well. However, when I try to handle Hindi plus English or Hinglish audios where there is code switching between English and Hindi, then it falls apart significantly.
AssemblyAI has impacted my organization positively, but I could not use it later on because it did not pass the quality benchmarks.
What needs improvement?
AssemblyAI can be improved by enhancing their voice models and supporting English plus Hindi code switching, similar to an AI model like Sarvam.
For how long have I used the solution?
I first used AssemblyAI around one year ago, and then I used it again recently, so I have approximately 1.5 years of experience using AssemblyAI.
What other advice do I have?
On a scale of one to ten, I would rate AssemblyAI around seven to eight for English transcription.
I choose an eight for English transcription because it handles the transcription pretty well.
My advice to others looking into using AssemblyAI is that if you are using it for English transcription and your primary goal consists of only English audios, then I recommend it. It is affordable, performs better than alternatives, and it has been available for a long time, so customer support should also be good. It is affordable and easily integrated, requiring minimal hassle—just API calls.
The quality benchmarks AssemblyAI did not pass are related to Hinglish audio; specifically, it was not able to diarize or transcribe it properly.
My overall rating for AssemblyAI is eight out of ten.