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Software · head to head

Cartesia vs Grammarly

Cartesia logo

Cartesia

Software

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

From
Free
Rated
-
Full reviewWebsite
Grammarly logo

Grammarly

Software

Great writing, simplified

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.; Grammarly occasional false positives and grammatically incorrect suggestions that can introduce errors
  • They diverge on capability: Cartesia covers Sonic text-to-speech, Grammarly covers Grammar checking.

Where they differ

Only the attributes on which Cartesia and Grammarly actually diverge.

Attributes where Cartesia and Grammarly differ
AttributeCartesiaGrammarly
Pricing modelfreemiumUnknown
Platformsweb, apiWeb, macOS, Windows, iOS, Android
FoundedUnknown2009

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Unknown).

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 Grammarly

  • Grammar checking
  • Spelling correction
  • Punctuation
  • Clarity suggestions
  • Engagement feedback
  • Delivery insights
  • Plagiarism checker
  • Citation generator

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 Grammarly
  • Real-time transcription for conversational applicationsnot Grammarly
  • Voice cloning for branded synthetic voicesnot Grammarly
  • On-device or on-premise voice AI for regulated industriesnot Grammarly

Grammarly

  • Email writingnot Cartesia
  • Document editingnot Cartesia
  • Academic writingnot Cartesia
  • Business communicationnot Cartesia
  • Content creationnot 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.

Grammarly

  • Occasional false positives and grammatically incorrect suggestions that can introduce errors
  • Privacy concerns about sending text to Grammarly's servers for analysis
  • AI capabilities sometimes produce hallucinations and fabricated citations that appear grammatically correct

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

Grammarly

Free
  • FreeFree
    • Basic grammar and spelling checks
    • Tone visibility
    • 100 AI prompts per month
  • Pro$12/month
    • Sentence rewrites
    • Tone adjustment
    • Plagiarism and AI detection

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 Grammarly if

  • You need grammar checking.
  • You want to start without paying.
  • You work on Web, macOS, Windows, iOS, Android.
  • You also want spelling correction.
Grammarly review

Questions people ask

Is Cartesia or Grammarly better?
Neither clearly leads. Cartesia starts at Free and Grammarly at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Cartesia or Grammarly?
Cartesia starts at Free and Grammarly at Free.
Does Cartesia or Grammarly run on more platforms?
Cartesia runs on web, api. Grammarly runs on Web, macOS, Windows, iOS, Android.
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 Grammarly is typically brought in for.
What can Cartesia do that Grammarly cannot?
Cartesia covers Sonic text-to-speech, Ink speech-to-text, Line voice agent platform, Instant and professional voice cloning. Grammarly covers Grammar checking, Spelling correction, Punctuation, Clarity suggestions.

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
Grammarly: Does Grammarly have a free version?

Yes, Grammarly offers a free tier with basic spelling, grammar, and punctuation checks, tone visibility, and 100 AI prompts per month. The Pro plan ($12/month annual) adds sentence rewriting, plagiarism detection, and 2,000 AI prompts.

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
Grammarly: What platforms does Grammarly work with?

Grammarly works across 1 million+ apps including Google Docs, Microsoft Word, Outlook, Slack, Gmail, and web browsers. It also integrates with productivity tools like Asana, Jira, Monday.com, Confluence, and HubSpot.

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
Grammarly: Can I use Grammarly offline?

Grammarly requires an internet connection to function, though the browser extension works with some offline text areas. For offline use, the desktop app and browser extensions sync when reconnected.

Source
Grammarly: What is included in the Enterprise plan?

The Enterprise plan includes unlimited team members, dedicated support, custom roles and permissions, data loss prevention, bring-your-own-key encryption, and unlimited AI prompts. Pricing is custom and available by contacting sales.

Source
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