AssemblyAI vs Rev AI

On batch pricing, Rev AI is slightly cheaper at about $0.0033/audio-min versus AssemblyAI at $0.0035/audio-min, a small but real difference. On SDKs, Rev AI offers five official SDK languages (Python, JS/TS, Java, Go, Ruby) compared to AssemblyAI's two (Python and JavaScript/Node), giving Rev AI a meaningful edge there. Both tools offer WebSocket streaming APIs, word-level timestampsword-level timestamps - The API reports exactly when each word is spoken in the audio, for subtitles and highlighting., and broad format support, making those attributes a wash. AssemblyAI supports 30+ audio and video formats explicitly, while Rev AI covers all FFmpeg formats, which are comparably broad. The heavier-weighted attributes split: Rev AI leads on price and SDK breadth, while AssemblyAI ties or trails on those same attributes. Neither tool dominates across the heaviest-weighted criteria.

The available facts cover API-level attributes for both AssemblyAI and Rev AI, such as batch pricing, streaming latency, WERWER - Word error rate - the share of words a transcription gets wrong; lower is more accurate. benchmarks, and concurrency limits. None of them address the attributes that matter for a dictation use case: supported desktop or mobile platforms, whether audio is processed on-device or sent to the cloud, AI formatting and auto-correction features, one-time versus subscription app pricing, or integrations with word processors and other software. Without facts on any of these five weighted attributes, neither tool can be distinguished for voice-typing dictation on a personal computer.

For clinical transcription under US healthcare privacy law, the HIPAA BAAHIPAA BAA - A signed Business Associate Agreement that lets you handle protected health information under US healthcare privacy law. is the decisive gate. AssemblyAI includes a HIPAA BAA on all plans, while Rev AI restricts it to enterprise customers only. That single factor, weighted at 5/5, creates a strong baseline advantage for AssemblyAI. On PII redaction, weighted at 4/5, AssemblyAI offers it as a paid add-on at about $0.001333 per audio minute, whereas no PII redaction capability is published for Rev AI. Both tools offer custom vocabulary boosting and hold SOC 2 Type II certification. AssemblyAI also supports a self-host option, adding a compliance-friendly deployment path that Rev AI does not publish. The combination of inclusive HIPAA BAA access and available PII redaction makes AssemblyAI the clear fit for medical workflows.

For meeting transcription, speaker diarizationdiarization - Splitting a transcript by speaker, so you can see who said what. is the top-weighted factor. AssemblyAI includes diarization as a paid add-on at about $0.02 per hour, while Rev AI includes it in the base price, giving Rev AI a slight edge there. However, AssemblyAI's third-party benchmark WER of 3.02% versus Rev AI's 5.92% means transcripts are substantially more accurate, which matters greatly for meetings. On languages, AssemblyAI supports 99 versus Rev AI's 57, a meaningful gap for diverse meeting participants. For file handling, AssemblyAI allows up to 5 GB and 10 hours per file, while Rev AI caps multipart uploads at 2 GB, making AssemblyAI better suited to long recordings. Both tools offer summarization and word-level timestamps. The accuracy advantage, broader language coverage, and superior file size limits tip the balance decisively.

AssemblyAI explicitly supports self-hostedself-host - Run the software on your own servers instead of the vendor’s cloud. and on-premises deployment, which is the single most critical requirement for this use case. Rev AI, by contrast, has no verified self-host option, and its model weights are available only under a non-commercial license (the Rev Model Non-Production License), blocking any production self-hosted deployment. AssemblyAI's confirmed on-premises availability versus Rev AI's non-commercial-only weights restriction makes this a decisive difference on the two heaviest attributes. No hardware requirements or model size facts are published for either tool, so those attributes are neutral.

For voice agents, streaming latency is the top priority. AssemblyAI publishes a vendor-claimed latency of 150 ms, while Rev AI provides no comparable figure. Both tools offer WebSocket streaming APIs, so that attribute is tied. On streaming price, AssemblyAI charges $0.0075 per audio minute versus no published streaming rate from Rev AI for its equivalent tier, leaving no comparable figure working against AssemblyAI. On concurrencyconcurrency - How many phone calls the platform can handle at the same time., AssemblyAI supports 100 new streams per minute on the base plan, while Rev AI caps base-plan streaming at just 10 concurrent streams, a dramatic difference for any production voice bot deployment. Both tools support custom vocabulary boosting. The combination of a published low-latency figure and vastly higher streaming concurrency makes AssemblyAI the clear choice for live voice agent workloads.