Smallest.ai
Smallest AI · Voice & Language
Smallest.ai is a real-time voice AI platform with Lightning text to speech, Pulse speech to text, and hosted voice agents that run over the phone, on the web, or inside your app.
About Smallest.ai
What Is Smallest.ai
Smallest.ai is voice infrastructure rather than a single consumer app. It ships four model families under one account and one API key: Lightning for text to speech, Pulse for speech to text, Electron as a small language model for the reasoning turn, and Hydra for speech to speech. A hosted layer on top, Voice Agents, wraps those models into agents that answer calls, follow a prompt, and reach your customers on a phone line or a web widget.
The company's bet is that many focused small models beat one giant general one. Electron is a sub-3B language model that Smallest says outperforms GPT-4.1 on the tasks it targets, and the whole pitch is speed. Lightning returns the first audio byte in about 200ms, which is the range a natural conversation needs.
The limits matter just as much. This is developer and team infrastructure, so there's no drag-and-drop voice editor for a one-off voiceover. Hydra speech to speech is English only today, and the deepest multilingual voice catalogs lean toward English, Hindi, and Indian languages rather than a uniform global list.
Getting Started
- Create an account in the Smallest AI console and open the API Keys page, then generate a key.
- Send your first request to the text to speech endpoint, or pick the Pulse endpoint if you need transcription, and confirm audio comes back.
- For a full agent, open the Voice Agents dashboard, pick a template or start blank, and write the prompt.
- Choose a voice, attach tools or a knowledge base, test the agent in the browser, then connect a phone number or an embed for web and mobile.
Product Information
A quick look at Smallest.ai's pricing, supported platforms, and performance.
Best for
The users, tasks, and scenarios where this tool fits best.
Users
- Developers building voice features
- Support and sales teams
- Startups that need speed more than scale
Tasks
- Turning text into speech at low latency
- Transcribing calls and recordings
- Running a talking agent end to end
Scenarios
- Building an AI receptionist
- Localizing a voice product
- Testing a voice idea before committing
Key features
Lightning text to speech
Lightning is the speech engine, and it comes in two pools. Lightning v3.1 is the standard pool with 217 voices, 12 trained-voice languages, and instant voice cloning from a 5 to 15 second sample. Lightning v3.1 Pro is the premium pool with a curated catalog across American, British, and Indian accents, English and Hindi code switching, and 29 more languages. Both return the first byte in about 200ms.
Pulse speech to text
Pulse transcribes live and pre-recorded audio, and its multilingual build covers streaming and batch in dozens of languages. It adds speaker diarization, timestamps, keyword boosting, and redaction of sensitive terms. A separate Pulse Pro model focuses on English accuracy for recorded files, and Pulse 2.0 is an English streaming model with end-of-turn detection, emotion, and gender detection built in.
Hosted voice agents
The Voice Agents platform is the piece that turns models into a product. You configure a prompt, a voice, a language, and tools in the dashboard, and Smallest runs speech to text, the reasoning turn, text to speech, and telephony. You can test the agent in the browser before it ever touches a real line.
Electron small language model
Electron is an OpenAI-compatible LLM built for the thinking step of a voice agent, with a fast first token and support for tool calling. It's a sub-3B model, and Smallest positions it against much larger models on the tasks a voice agent actually runs, which is a claim worth testing against your own prompts.
Hydra speech to speech
Hydra skips the transcript in the middle. It takes audio in and returns audio out over a single WebSocket, handles barge-in when a caller interrupts, and calls your tools directly. It's the shortest path to a natural back-and-forth, and today it runs in English.
Voice cloning and a large voice library
On the standard Lightning pool you can clone a voice from a short sample, which is enough for a branded read or a consistent narrator. Across the pools you get a few hundred preset voices, and Lightning v3.1 Pro adds dedicated voices for languages beyond English and Hindi, including Dutch and Swedish.
Telephony and multi-channel delivery
Agents aren't stuck in a web page. You can rent phone numbers, bring your own SIP trunk, and run outbound campaigns, or embed the same agent in a web widget, an iOS or Android app, or a Flutter build. Webhooks and integrations with LiveKit, Pipecat, and the Vercel AI SDK cover teams that already have a pipeline.
Pros and cons
Pros
- One API key covers text to speech, speech to text, an LLM, and speech to speech, so you assemble a voice stack without stitching together four vendors.
- Latency is the headline, and Lightning's roughly 200ms first byte is fast enough to keep a spoken conversation flowing.
- The pay-as-you-go plan starts with free credits and no contract, which keeps early experiments cheap.
- Voice cloning and a few hundred voices sit in the standard pool, so you don't need the premium tier just to get variety.
- Self-hosting is documented for the core models, an option that matters if your data can't leave your own cloud.
Cons
- The deepest voice and translation coverage leans English, Hindi, and Indian languages, so check your target language before you commit.
- Hydra speech to speech is English only right now, which rules it out for multilingual agents.
- There's no standalone consumer app for a quick voiceover, so a non-developer has little to click.
- Heavy telephony and enterprise features route through sales rather than a public price list, which slows down budgeting.
Frequently asked questions
Smallest.ai is voice AI infrastructure. It converts text to speech, transcribes audio, and hosts voice agents that handle phone calls and web chats, all through one platform and API.
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