Inworld AI review: Voice and open-LLM APIs for developers building consumer AI apps
Voice and open-LLM APIs for developers building consumer AI apps
Starts at $25/mo, free plan: yes, prices checked on October 29, 2026.
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What Inworld AI does
Inworld AI is a research lab and inference provider that targets consumer AI apps such as companions, tutors, wellness coaches and games. Developers reach it through an API. The voice side covers text to speech with Realtime TTS-2 and Realtime TTS-2 Flash, speech to text with Realtime STT-1, and a speech to speech option that runs listening, reasoning and talking back over one connection, with the LLM chosen for each session. The speech to text docs add that the transcript can come with voice profile signals such as age, pitch, emotion, vocal style and accent.
Pricing is credit based. The On-Demand plan costs $0 and is pay as you go, with TTS-2 at $25 per 1M characters and TTS-2 Flash at $15. Paid monthly plans are Creator at $25, Builder at $100, Developer at $300 and Growth at $1,500; each grants credits equal to its price, and higher tiers lower the per-unit rates. Enterprise pricing is custom, with TTS-2 as low as $5 per 1M characters. Unused credits roll over for 3 months while a paid subscription is active.
Stated limits include concurrent request caps that grow with each plan, starting at 5 on On-Demand, and a TTS Playground character limit of 2,000 on On-Demand versus 40,000 on paid tiers.
- Realtime text to speech (TTS-2 and TTS-2 Flash)
- Realtime speech to text (STT-1)
- Voice profile signals with transcripts
- Speech to speech over one connection
- Choose the LLM per session
- Open LLMs via OpenAI-compatible API
- Voice cloning and voice design
- Playground for trying models
Good for / Not for
Good for
- Developers building voice agents or companions who want TTS, STT and an LLM from one vendor
- Teams that want to test voice models free before choosing a paid plan
- Apps that need voice cloning or custom voices at larger scale
Not for
- People wanting a finished consumer app rather than an API
- Buyers who need published Enterprise prices or a stated trial length
How to start
Generate an API key, then make a single request: a text to speech call, a Realtime STT-1 transcript, or a chat completion sent to an open model. source
Try the voices and models in the playground before writing code. source
Start on the free On-Demand plan, which includes up to 70 minutes of TTS, then pick a paid plan if needed. source
Limits and gotchas
- On-Demand has 5 concurrent requests and a 2,000-character TTS Playground limit; paid tiers raise these. source
- Unused credits roll over for up to 3 months, and remaining credits are forfeited on downgrade or cancellation. source
- HIPAA & BAA and zero data retention are add-ons on Growth; SLA & DPA and data residency are Enterprise features. source
From the official site and docs of Inworld AI, checked on October 29, 2026.
Pros and cons
Pros
- Free On-Demand plan with 70 minutes of TTS included
- Text to speech, speech to text, speech to speech and LLM inference under one credit balance
- Unused credits roll over for 3 months on paid plans
- Per-character TTS rates fall from $25 on On-Demand to $12.50 on Growth
- GDPR and SOC 2 Type II listed on every plan
Cons
- Delivered as an API; no standalone app is described on the pages
- Yearly-billed prices are not shown, so no annual comparison is possible
- Playground TTS character limit is only 2,000 on the free plan
- Concurrent request limits are low on lower tiers, starting at 5 on On-Demand
Our take
Inworld AI suits developers and small teams who want voice generation, transcription and hosted open LLMs from one vendor, billed from a single credit balance. The free On-Demand plan makes it possible to test the products before paying, and the Playground lets you listen to voices before writing code. It is less suited to people who want a ready-made consumer app, since everything is delivered as APIs, and the pages name no web, mobile or desktop client. Anyone needing a stated free trial length should check with the vendor.
Comparisons and lists with Inworld AI
Coming soon
Coming soon — we are writing comparisons that include Inworld AI.
Inworld AI pricing
| Plan | Monthly billing | Annual billing (per month) | Limits / what’s included |
|---|---|---|---|
| On-Demand pay as you go | Free | — | TTS-2 $25/1M chars; TTS-2 Flash $15/1M chars; STT $0.15/hr; up to 70 min TTS included; 100 custom voices; 5 concurrent requests |
| Creator per month | $25 | — | $25 in credits per month; TTS-2 $20/1M chars; TTS-2 Flash $10/1M chars; STT $0.10/hr; 500 custom voices; 4 professional voice clones; 10 concurrent requests |
| Builder per month | $100 | — | $100 in credits per month; TTS-2 $17.50/1M chars; TTS-2 Flash $9/1M chars; 3,000 custom voices; 10 professional voice clones; 50 concurrent requests |
| Developer per month | $300 | — | $300 in credits per month; TTS-2 $15/1M chars; TTS-2 Flash $8/1M chars; 10,000 custom voices; 25 professional voice clones; priority email support; 150 concurrent requests |
| Growth per month | $1,500 | — | $1,500 in credits per month; TTS-2 $12.50/1M chars; TTS-2 Flash $7/1M chars; 30,000 custom voices; 40 professional voice clones; HIPAA & BAA and ZDR as add-ons; 500 concurrent requests |
| Enterprise custom pricing | — | — | TTS-2 as low as $5/1M; custom limits; 100+ professional voice clones; SLA & DPA; EU & India data residency |
Free trial: none listed. Free plan: yes.
Prices checked on on the official Inworld AI pricing page. “—” = not published.
All Inworld AI plans, limits and annual prices →
Frequently asked questions
Does Inworld AI have a free plan?
Yes. The On-Demand plan costs $0 on a pay-as-you-go basis and includes up to 70 minutes of TTS so you can try the products.
How much do the paid plans cost?
Creator is $25 per month, Builder $100, Developer $300 and Growth $1,500, shown on the pricing page. Each gives credits equal to its price. Enterprise is custom.
Do unused credits expire?
Subscription credits roll over for up to 3 months while you keep an active paid subscription of equal or higher value.
Can I pick my own LLM for a voice agent?
Yes. The speech to speech API lets you choose the LLM for each session and handles the conversation over one connection.
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