# Gradium vs Vapi

Gradium records 126,416 monthly visits with +128.7% month-over-month growth and Freemium, Contact for Pricing pricing. Vapi records 662,301 monthly visits with -11.4% growth and Freemium pricing.

| Metric | [Gradium](https://openaitools.app/tool/gradium) | [Vapi](https://openaitools.app/tool/vapi) |
| :--- | :--- | :--- |
| Website URL | https://gradium.ai | https://vapi.ai |
| Categories | AI Text-to-Speech, AI Speech-to-Text, AI Voice Cloning, AI API | AI Agent, AI API, AI Voice Assistants, AI Developer Tools |
| Pricing Model | Freemium, Contact for Pricing | Freemium |
| Monthly Visits | 126,416 | 662,301 |
| MoM Growth Rate | +128.7% | -11.4% |
| Primary Market | France | United States |
| Direct Visits | 27,158 | 377,321 |
| Review Score | 4.5 | 4.5 |
| Saved Count | 0 | 2 |
| Supported Platforms | Website | Website |

## Gradium

Gradium targets teams building conversational voice agents, telephony bots, and real-time translation experiences where latency decides whether a product feels natural. Its model lineup covers the full loop: text-to-speech for synthesis, speech-to-text for transcription, live voice-to-voice translation, instant cloning from a short audio sample, pro cloning for production-grade custom voices, and voice design that creates a brand-new voice from a text description alone.

The platform is API-first, with SDKs for Python and Rust, WebSocket streaming, semantic voice activity detection, custom vocabularies, code-switching support, and integrations such as LiveKit and Pipecat so teams can drop it into existing agent stacks. Gradium also ships Phonon, an open on-device TTS model that can run offline, which matters for privacy-sensitive or embedded deployments.

Pricing is credit-based across five self-serve tiers plus enterprise. Credits map to usage: text-to-speech costs 1 credit per character, speech-to-text 3 credits per second, speech-to-text translation 4 credits per second, and speech-to-speech translation 30 credits per second. Higher tiers unlock commercial use, more custom voices, pro clones, and better concurrency, while enterprise adds dedicated inference, on-premises deployment, and options such as Baseten or SageMaker endpoints.

**Pricing & Plans:** Free tier with 45k credits per month. Paid plans run $12/mo (XS), $39/mo (S), $312/mo (M), and $1,480/mo (L) on monthly billing, with yearly billing giving one month free. Usage is credit-based (1 credit per TTS character, 3 credits per STT second, 30 credits per second for speech-to-speech translation). Enterprise pricing is custom.

- **Ultra-low-latency voice models:** Text-to-speech, speech-to-text, and live speech-to-speech translation reach roughly 50 ms to first audio, tuned for conversational agents rather than batch processing.
- **Tiered voice cloning and voice design:** Clone a voice from a short sample for everyday use, move up to pro cloning for production quality, or generate a brand-new voice from a text description.
- **Developer-first API and SDKs:** WebSocket streaming, Python and Rust SDKs, custom vocabulary, semantic VAD, and code-switching support make integration straightforward for agent builders.
- **Open on-device TTS with Phonon:** Phonon is Gradium's openly available TTS model that runs on-device for offline or privacy-sensitive deployments.
- **Scaling and deployment options:** Gradium handles concurrency tiers for growing traffic and supports dedicated inference, on-premises deployment, and Baseten or SageMaker endpoint hosting.

**Strengths:** Very low latency tuned specifically for live voice agents rather than offline batch jobs; Full voice stack in one API: TTS, STT, translation, cloning, and voice design; Genuine free tier (45k credits/month) and low $12/mo entry point for prototyping; Enterprise-grade options including on-premises deployment, data residency, and an open on-device TTS model

**Limitations:** Credit-based pricing is harder to forecast than flat per-seat plans, and unused plan credits expire monthly; Pro voice cloning and higher concurrency sit behind the larger monthly tiers; Feature depth varies by plan, so commercial use requires at least the XS tier

[Profile (Markdown)](https://openaitools.app/tool/gradium.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 Gradium and Vapi compare in monthly traffic?

Gradium has 126,416 monthly visits, while Vapi has 662,301. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

Gradium has a month-over-month growth rate of +128.7%; Vapi has -11.4%.

### How does pricing compare?

Gradium: Freemium, Contact for Pricing. Free tier with 45k credits per month. Paid plans run $12/mo (XS), $39/mo (S), $312/mo (M), and $1,480/mo (L) on monthly billing, with yearly billing giving one month free. Usage is credit-based (1 credit per TTS character, 3 credits per STT second, 30 credits per second for speech-to-speech translation). Enterprise pricing is custom. 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 | [Fish Audio](https://openaitools.app/tool/fish-speech) | 8,557,159 | +1.6% | Freemium | Studio-grade AI text to speech and voice cloning | [.md](https://openaitools.app/tool/fish-speech.md) |
| 5 | [Groq](https://openaitools.app/tool/groq) | 3,987,936 | +10% | Paid | Ultra-fast AI inference on the LPU and LPX platform | [.md](https://openaitools.app/tool/groq.md) |
| 6 | [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) |
| 7 | [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) |
| 8 | [AssemblyAI](https://openaitools.app/tool/assemblyai) | 453,591 | -6.9% | Freemium, Contact for Pricing | Provides enterprise-grade speech-to-text and audio intelligence APIs, but lacks turnkey conversational voice agent telephony orchestration. | [.md](https://openaitools.app/tool/assemblyai.md) |
| 9 | [Noiz AI](https://openaitools.app/tool/noiz-ai) | 441,445 | -30.1% | Paid | Clone voice, control emotion, and create lifelike speech. | [.md](https://openaitools.app/tool/noiz-ai.md) |
| 10 | [Soniox](https://openaitools.app/tool/soniox) | 335,647 | +2.2% | Paid | One speech AI API for recognition, generation, and translation in 60+ languages | [.md](https://openaitools.app/tool/soniox.md) |

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

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