# AssemblyAI vs Vapi

AssemblyAI records 453,591 monthly visits with -6.9% month-over-month growth and Freemium, Contact for Pricing pricing. Vapi records 662,301 monthly visits with -11.4% growth and Freemium pricing.

| Metric | [AssemblyAI](https://openaitools.app/tool/assemblyai) | [Vapi](https://openaitools.app/tool/vapi) |
| :--- | :--- | :--- |
| Website URL | https://www.assemblyai.com | https://vapi.ai |
| Categories | AI Speech-to-Text, AI Transcription, AI Speech Recognition, AI Developer Tools | AI Agent, AI API, AI Voice Assistants, AI Developer Tools |
| Pricing Model | Freemium, Contact for Pricing | Freemium |
| Monthly Visits | 453,591 | 662,301 |
| MoM Growth Rate | -6.9% | -11.4% |
| Primary Market | Brazil | United States |
| Direct Visits | 281,472 | 377,321 |
| Review Score | 4.6 | 4.5 |
| Saved Count | 9 | 2 |
| Supported Platforms | Website | Website |

## AssemblyAI

AssemblyAI builds speech AI models and the infrastructure to run them, aimed at developers and product teams adding voice to an application. Its core offering is speech-to-text: an asynchronous API for pre-recorded audio, a realtime API for streaming and voice agents, and a synchronous API for short clips and dictation. The company's flagship accuracy model is marketed as top of independent benchmarks, with strong speaker diarization and native code-switching across dozens of languages.

On top of transcription, AssemblyAI offers a Speech Understanding API that layers tasks such as summarization, sentiment, topic detection, PII redaction, content moderation and guardrails onto transcripts. It has also released its first text-to-speech model, AssemblyAI-TTS-1, built for voice agents on live calls, plus an LLM Gateway for routing model calls and a Dictation API. Models can run on AssemblyAI's managed inference cloud, or self-hosted in a customer's own VPC or on-premises environment.

Pricing is pay-as-you-go after a free trial: for example, pre-recorded transcription is billed per audio hour, with optional add-ons such as speaker diarization, keyterms prompting and medical or veterinary modes priced separately. Enterprise plans offer custom rate limits, higher concurrency and compliance features including SOC 2 Type 2, HIPAA and GDPR.

**Pricing & Plans:** Free trial to start, then pay-as-you-go per audio hour and per add-on feature — for example around $0.15/hr for the Universal-2 model and around $0.21/hr for the more accurate Universal-3.5 Pro model, with extras like diarization billed individually. Enterprise and custom-rate-limit plans are available via sales.

- **Async, realtime and sync speech-to-text:** Choose pre-recorded transcription for files, a realtime API for live streams and voice agents, or a synchronous endpoint for short clips and dictation.
- **Audio intelligence and Speech Understanding:** Layer summarization, sentiment, topic detection, PII redaction, content moderation and guardrails onto transcripts without building your own models.
- **Text-to-speech for voice agents:** AssemblyAI-TTS-1 is trained on real phone calls for natural, low-latency speech, targeted at IVR and voice-agent use cases.
- **High accuracy with diarization:** Flagship models emphasise exact transcription, speaker labels and native code-switching across many languages, supported by published benchmarks.
- **Flexible deployment:** Run models on AssemblyAI's managed cloud with unlimited concurrency, or self-host in your own VPC or on-prem for full data control.

**Strengths:** One API family covering transcription, understanding and text-to-speech; Transparent per-hour pay-as-you-go pricing with a free trial; Self-hosting option for teams with strict data-residency requirements; Strong accuracy and diarization performance backed by published benchmarks

**Limitations:** Costs scale with volume and add-ons can raise the effective per-hour rate; Some advanced features are model-specific and not available on every model; Heavier product surface than a simple transcription API may be overkill for basic needs

[Profile (Markdown)](https://openaitools.app/tool/assemblyai.md)

## Vapi

Vapi gives engineering teams a managed stack for real-time voice agents. Rather than stitching together a speech-to-text provider, an LLM, a text-to-speech vendor and a telephony carrier, teams configure those pieces through Vapi's API and dashboard. The platform handles the low-latency orchestration, barge-in handling, and call routing that make a natural back-and-forth conversation possible.

Beyond the raw API, Vapi ships observability and evaluation tooling: call logs, transcripts, effectiveness and compliance monitoring, and call simulation so agents can be tested before they reach customers. Integration hooks let agents read and write to CRMs, calendars, ticketing systems and internal APIs, which is what turns a demo bot into a working support or scheduling agent.

Vapi targets both individual builders who start on free credits and enterprises that need contractual SLAs, SSO/OAuth/RBAC, HIPAA-eligible handling and dedicated engineering support. Pricing is metered by the minute, with model costs passed through at provider rates.

**Pricing & Plans:** Usage-based. New accounts get $5 in free credits; Vapi hosting is prepaid at about $0.05/min with transcription, LLM and voice billed as pass-through provider costs. Optional success packages: Core at $29/month, Pro at 10% of hosting fees with a $999/month minimum, and a custom Premier tier for enterprises. Add-ons include extra concurrency at $10/line/month and HIPAA handling at $2,000/month.

- **Unified voice agent API:** Configure speech recognition, an LLM reasoning layer and text-to-speech through one API instead of integrating several vendors separately.
- **Managed low-latency orchestration:** The platform handles real-time audio streaming, interruption handling and call state so conversations feel natural and responsive.
- **Built-in telephony and numbers:** Provision Vapi phone numbers or bring Twilio, Vonage or Telnyx, and support both inbound and outbound calling from the same agent.
- **Testing and observability:** Simulate calls before launch, then track transcripts, effectiveness metrics and compliance signals across every production call.
- **Enterprise controls:** SOC 2, HIPAA and PCI aligned options, SSO, OAuth2, RBAC, zero data retention, uptime SLAs and dedicated deployment support.

**Strengths:** API-native design with full control over models, prompts and voices; Real-time infrastructure, telephony and monitoring handled for you; Transparent pricing with model costs passed through at provider rates; Strong enterprise feature set including compliance, SSO, RBAC and SLAs

**Limitations:** Total cost climbs quickly because hosting, models and transport are billed separately; The Pro success package has a high $999/month minimum; Advanced configuration assumes real development resources

[Profile (Markdown)](https://openaitools.app/tool/vapi.md)

## Frequently Asked Questions

### How do AssemblyAI and Vapi compare in monthly traffic?

AssemblyAI has 453,591 monthly visits, while Vapi has 662,301. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

AssemblyAI has a month-over-month growth rate of -6.9%; Vapi has -11.4%.

### How does pricing compare?

AssemblyAI: Freemium, Contact for Pricing. Free trial to start, then pay-as-you-go per audio hour and per add-on feature — for example around $0.15/hr for the Universal-2 model and around $0.21/hr for the more accurate Universal-3.5 Pro model, with extras like diarization billed individually. Enterprise and custom-rate-limit plans are available via sales. Vapi: Freemium. Usage-based. New accounts get $5 in free credits; Vapi hosting is prepaid at about $0.05/min with transcription, LLM and voice billed as pass-through provider costs. Optional success packages: Core at $29/month, Pro at 10% of hosting fees with a $999/month minimum, and a custom Premier tier for enterprises. Add-ons include extra concurrency at $10/line/month and HIPAA handling at $2,000/month.

## Alternatives

| # | Tool Name | Monthly Visits | MoM Growth Rate | Pricing Model | Summary | Profile (Markdown) |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | [OpenAI Platform](https://openaitools.app/tool/openai) | 234,678,639 | -9.6% | Paid | Provides raw frontier language models and real-time multimodal capabilities, requiring custom scaffolding compared to Vapi's voice workflows. | [.md](https://openaitools.app/tool/openai.md) |
| 2 | [Google AI Studio](https://openaitools.app/tool/google-ai-studio) | 112,620,020 | +2% | Freemium | Offers developer access to Gemini's powerful multimodal APIs, but lacks out-of-the-box telephony voice agent pipelines. | [.md](https://openaitools.app/tool/google-ai-studio.md) |
| 3 | [ElevenLabs](https://openaitools.app/tool/elevenlabs-io) | 42,396,771 | +26.1% | Freemium, Paid, Contact for Pricing | Industry leader in ultra-realistic voice cloning and text-to-speech, now offering robust conversational voice agent capabilities. | [.md](https://openaitools.app/tool/elevenlabs-io.md) |
| 4 | [Cartesia](https://openaitools.app/tool/cartesia-ai) | 1,782,707 | +49.7% | Contact for Pricing | Provides ultra-low latency text-to-speech and managed voice agents via developer API, rivaling Vapi's audio speed. | [.md](https://openaitools.app/tool/cartesia-ai.md) |
| 5 | [Deepgram Voice AI](https://openaitools.app/tool/deepgram-voice-ai) | 863,852 | +31.8% | Free Trial | Delivers robust real-time speech-to-text and voice agent APIs, though with less telephony-specific orchestration than Vapi. | [.md](https://openaitools.app/tool/deepgram-voice-ai.md) |
| 6 | [Soniox](https://openaitools.app/tool/soniox) | 335,647 | +2.2% | Paid | Delivers high-accuracy speech-to-text and translation across numerous languages, but with a more streamlined feature set. | [.md](https://openaitools.app/tool/soniox.md) |
| 7 | [Bland AI](https://openaitools.app/tool/bland-ai) | 243,601 | +7.4% | Paid, Contact for Pricing | Enterprise voice AI platform specializing in high-volume outbound and inbound phone calls with robust telephony integrations. | [.md](https://openaitools.app/tool/bland-ai.md) |
| 8 | [Gladia](https://openaitools.app/tool/gladia) | 232,451 | +6.4% | Freemium, Contact for Pricing | Provides robust multilingual transcription and audio intelligence APIs with a strong focus on developer-friendly infrastructure. | [.md](https://openaitools.app/tool/gladia.md) |
| 9 | [Gradium](https://openaitools.app/tool/gradium) | 126,416 | +128.7% | Freemium, Contact for Pricing | Offers ultra-low latency speech-to-speech APIs and voice cloning, ideal for real-time conversational agent pipelines. | [.md](https://openaitools.app/tool/gradium.md) |
| 10 | [Synthflow.ai](https://openaitools.app/tool/synthflow-ai) | 95,542 | -7.6% | Free Trial, Contact for Pricing | A conversational platform for building AI voice agents, favoring no-code and enterprise workflows over raw developer APIs. | [.md](https://openaitools.app/tool/synthflow-ai.md) |

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Source: https://openaitools.app/compare/assemblyai-vs-vapi

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