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AI · head to head

Cartesia vs Helicone

Cartesia logo

Cartesia

AI

Real-time voice AI platform for speech generation, transcription, and voice agents

From
Free
Rated
-
Full reviewWebsite
Helicone logo

Helicone

AI

Open-source LLM observability and gateway platform for AI applications

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Cartesia instant and professional voice cloning are gated behind paid Pro and Startup tiers, unavailable on the free plan.; Helicone the free Hobby plan is capped at 10,000 requests per month, which teams with production traffic can exceed quickly.
  • They diverge on capability: Cartesia covers Sonic text-to-speech, Helicone covers Request dashboard and tracking.
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Cartesia and Helicone actually diverge.

Attributes where Cartesia and Helicone differ
AttributeCartesiaHelicone

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), platforms (web, api), user rating (Not yet rated), category (AI).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Cartesia

  • Sonic text-to-speech
  • Ink speech-to-text
  • Line voice agent platform
  • Instant and professional voice cloning
  • Flexible deployment
  • Telephony integration

Only in Helicone

  • Request dashboard and tracking
  • Sessions and segments
  • Helicone Query Language (HQL)
  • Prompt datasets and improvement
  • Playground
  • Rate limits and alerts

What people use each for

The jobs each tool is most often brought in to do.

Cartesia

  • Building low-latency voice agents for customer supportnot Helicone
  • Real-time transcription for conversational applicationsnot Helicone
  • Voice cloning for branded synthetic voicesnot Helicone
  • On-device or on-premise voice AI for regulated industriesnot Helicone

Helicone

  • Monitoring cost and latency of production LLM applicationsnot Cartesia
  • Debugging multi-step agent sessionsnot Cartesia
  • Managing and iterating on prompts across a teamnot Cartesia
  • Routing requests across multiple LLM providersnot Cartesia

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Cartesia

  • Instant and professional voice cloning are gated behind paid Pro and Startup tiers, unavailable on the free plan.
  • Voice agent calls carry a separate per-minute usage fee ($0.06/minute) on top of subscription credits.
  • Enterprise features like SSO and BAAs require a custom sales conversation rather than self-serve upgrade.
  • Free tier concurrency limits (2 TTS, 8 STT concurrent requests) may be restrictive for testing production-like load.

Helicone

  • The free Hobby plan is capped at 10,000 requests per month, which teams with production traffic can exceed quickly.
  • Advanced compliance features like SOC 2 and HIPAA are only available starting at the $799/month Team plan.
  • Usage beyond the free tier is billed on top of the base subscription, adding cost unpredictability at scale.
  • On-premises deployment is restricted to the custom Enterprise tier.

Pricing, plan by plan

Cartesia

Free
  • FreeFree
    • 20,000 credits/month
    • TTS and STT included
    • 2 concurrent TTS requests, 8 concurrent STT requests
  • Pro$4/month
    • 100,000 credits/month
    • Commercial use license
    • Instant voice cloning
  • Startup$39/month
    • 1.25M credits/month
    • Professional voice cloning
    • Organizations support
  • Scale$239/month
    • 8M credits/month
    • Priority support
    • High concurrency limits

Helicone

Free
  • HobbyFree
    • 10,000 free requests
    • 1 GB storage
    • 1 seat
  • Pro$79/month
    • 10K free requests included, usage-based beyond
    • 7-day free trial
    • Unlimited playgrounds and workspaces
  • Team$799/month
    • 5 organizations
    • SOC 2 and HIPAA compliance
    • Dedicated Slack channel access
  • Enterprise$undefined/mo
    • Custom MSAs and SAML SSO
    • On-premises deployment
    • Bulk cloud discounts

Which should you pick?

Choose Cartesia if

  • You need sonic text-to-speech.
  • You want to start without paying.
  • You work on web, api.
  • You also want ink speech-to-text.
Cartesia review

Choose Helicone if

  • You need request dashboard and tracking.
  • You want to start without paying.
  • You work on web, api.
  • You also want sessions and segments.
Helicone review

Questions people ask

Is Cartesia or Helicone better?
Neither clearly leads. Cartesia starts at Free and Helicone at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cartesia or Helicone?
Cartesia starts at Free and Helicone at Free.
Does Cartesia or Helicone run on more platforms?
Both run on web, api, so platform support will not decide this one for you.
Can I use Cartesia for free?
Both have a free tier, so you can try either at no cost before committing.
What is Cartesia best used for?
Cartesia is most often used for building low-latency voice agents for customer support, real-time transcription for conversational applications, voice cloning for branded synthetic voices, on-device or on-premise voice ai for regulated industries. Of those, building low-latency voice agents for customer support and real-time transcription for conversational applications are not what Helicone is typically brought in for.
What can Cartesia do that Helicone cannot?
Cartesia covers Sonic text-to-speech, Ink speech-to-text, Line voice agent platform, Instant and professional voice cloning. Helicone covers Request dashboard and tracking, Sessions and segments, Helicone Query Language (HQL), Prompt datasets and improvement.

Answered from the vendors’ own pages

Cartesia: What does Cartesia cost?

Cartesia offers a free plan, Pro at $4/month, Startup at $39/month, Scale at $239/month, and custom Enterprise pricing, each including a monthly credit allotment, with annual billing saving 20%.

Source
Helicone: What does Helicone cost?

Helicone offers a free Hobby plan, a Pro plan at $79/month, a Team plan at $799/month, and custom Enterprise pricing, with usage-based charges applying beyond included request limits.

Source
Cartesia: Is there a free plan, and what are its limits?

The Free plan includes 20,000 credits per month, both TTS (Sonic) and STT (Ink), 2 concurrent TTS requests, 8 concurrent STT requests, and 1 voice agent slot.

Source
Helicone: Is there a free plan, and what are its limits?

The free Hobby plan includes 10,000 requests per month, 1 GB of storage, 1 seat, and 1 organization, aimed at kickstarting AI projects.

Source
Cartesia: How is usage metered?

Usage draws down a monthly credit allotment, with voice agent calls additionally billed at $0.06/minute and telephony via Cartesia phone numbers at $0.014/minute.

Source
Helicone: Are there discounts available?

Helicone offers 50% off the first year for qualifying startups, discounts for non-profits, a $100 annual credit for open-source projects, and free access for students.

Source
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