Cartesia
Cartesia builds real-time-first voice models -- its Sonic TTS and Ink STT rank #1 on Artificial Analysis speech leaderboards for combined quality and speed. Built on state-space (Mamba-style) architectures for ultra-low latency, it's purpose-made for voice agents and powers platforms like Retell. One developer API covers TTS, STT, and voice agents, with a genuinely usable free tier (20K credits/mo) and paid plans from $5/mo, plus cloud, on-prem, and on-device deployment. The main friction is an abstract credit model and promo pricing that muddies the long-term cost.
Speechify
Speechify is the mainstream 'read anything aloud' assistant, claiming 55M+ users and topping the App Store's text-to-speech charts. The same engine is available as a developer TTS API (1,000+ voices, 60+ languages, instant voice cloning, SSML, streaming), so it spans consumers and builders. The free tier is deliberately thin -- 10 robotic voices, TTS-only -- and consumer Premium is $29/mo, while API pricing is signup-gated rather than public. Its edge is distribution and reach, not raw model novelty.
Cartesia edges Speechify on aggregate — 88 vs 79.
The latency king for real-time voice agents -- best-in-class speed and quality with a fair free tier, if you can stomach credit-based math. Speechify still wins for buyers who prioritise 1,000+ voices across 60+ languages. Both tools are independently scored — the right pick depends on which dimensions matter most for your workflow.
Side-by-side, every cell sourced.
Pricing pulled from each tool's public site. Scores follow the BigBang Score rubric — pricing transparency, free tier, API support, update frequency, unique factor, documentation, and community.
Use-case picks.
Cut through the spec sheet. Here's what we'd recommend depending on what matters most.
Pick Cartesia if…
You prioritise true free tier with a commercial upgrade path and #1-ranked real-time speech quality and speed.
Pick Speechify if…
You prioritise 1,000+ voices across 60+ languages and same api powers a 55m+ user product (battle-tested).
Editorial pick
Cartesia wins our composite score (88/100). It edges ahead on aggregate — but the right tool depends on which dimensions matter most.
Related head-to-heads in AI audio.
Cartesia vs ElevenLabs — AI audio
BigBang Scores 88/100 vs 88/100. Pricing, capabilities, and editorial verdict inside.
Cartesia vs AssemblyAI — AI audio
BigBang Scores 88/100 vs 88/100. Pricing, capabilities, and editorial verdict inside.
Cartesia vs OpenAI Whisper — AI audio
BigBang Scores 88/100 vs 88/100. Pricing, capabilities, and editorial verdict inside.
Cartesia vs Speechify - frequently asked.
Direct answers tuned for AI search engines (ChatGPT, Perplexity, Claude) and Google's People Also Ask.
The short answer.
Cartesia wins on aggregate, but Speechify pulls ahead on specific axes - the spec sheet above shows where each one earns its keep.