Cartesia alternative with no subscription: pay per character

Credit plans suit steady, high usage. If your usage is small or lumpy, you can end up paying for credits you do not spend. This page covers switching to pay-per-character.

Who switches

  • Your monthly volume is small or uneven and a $5 to $49 plan feels wasteful
  • You do not need very low latency or phone agents
  • Most of your speech is repeated prompts

What you gain

  • No subscription and no credits to expire
  • A per-character rate far below the effective $37 to $65 per million on Cartesia's plans
  • Ready-made English packs and a checked phrase library
  • Transcription at $0.0015 per minute against about $0.0065 on Ink (Scale)

What you give up

  • Sonic-class low-latency voices
  • Provisioned phone numbers for agents
  • Professional voice cloning slots
  • Cartesia's explicit output-format control (Speakvora returns M4A or MP3 links)

The code change

Request shapes were taken from each provider's own documentation on 2026-10-08. Provider APIs change; check theirs before you migrate.

Cartesia text to speech (docs: docs.cartesia.ai/api-reference/tts/bytes)

curl -X POST https://api.cartesia.ai/tts/bytes \
  -H "Authorization: Bearer $CARTESIA_API_KEY" -H "Cartesia-Version: 2026-08-14" -H "Content-Type: application/json" \
  -d '{"model_id":"sonic-3.6","transcript":"Hello, how can I help you today?","voice":{"id":"$VOICE_ID"},
       "output_format":{"container":"mp3","sample_rate":44100,"bit_rate":128000}}' \
  --output prompt.mp3
# response body is the audio bytes

Speakvora text to speech

curl -X POST https://speakvora.com/api/v1/speak \
  -H "x-api-key: $SPEAKVORA_KEY" -H "content-type: application/json" \
  -d '{"text":"Hello, how can I help you today?","voice":"af_heart","lang":"en"}'
# JSON reply: {"url":"https://speakvora.com/...m4a","lang":"en","voice":"af_heart","characters":32,"format":"m4a"}
curl -s "$URL" --output prompt.m4a        # second step: download (or play) the link

What changes in practice: Cartesia needs a `Cartesia-Version` header, a model ID and an output-format object, and returns raw audio. Speakvora needs neither: text, voice and language in, a link out, and you pick the format your player supports. The text limit is 500 characters per request, and Speakvora returns JSON with a url that you fetch or play. Library links are stable public files; custom-voice links last about five minutes.

A safe migration order

  1. List your top 50 spoken lines and their characters per month.
  2. Price them at $0.70 per million and compare to your plan.
  3. Move low-latency paths last, or keep them on Cartesia.
  4. Convert the audio your player expects (M4A or MP3) at the client if needed.

Is it actually cheaper?

Cartesia's text to speech costs 1 credit per character. The plans are Free (20K credits), Pro $5 (100K), Startup $49 (1.25M) and Scale $299 (8M), with overage priced per million credits at $65, $45 and $38. Dividing plan price by credits gives about $50 per million characters on Pro, $39 on Startup and $37 on Scale. Speakvora's catalog voices are $0.70 per million characters, with no monthly fee.

Full numbers, scenarios and sources: Speakvora vs Cartesia.

Test these before you commit

  • Measure end-to-end latency from your own servers; we do not claim to beat Sonic.
  • Add up your real monthly characters and compare against the Cartesia plan price, not the headline credits.
  • Check you are not relying on a provisioned phone number or professional cloning slots.
  • Try the free allowance first: 100,000 characters, no card, once per account.

Speakvora is in early access with billing is live; questions to support@eyeguide.ai. Latency: see the speed page.

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