Voice AI API + SDKs,
built for developers
Ship voice AI agents in minutes with a REST API, Python and JavaScript SDKs, webhooks and a no-code flow editor. BYOK providers, real-time WebRTC, native SIP for phone calls.
60-second quickstart
Place your first outbound voice call with a single API call. Pick your language — curl, Python, or JavaScript.
curl -X POST https://api.thinnest.ai/v1/calls \
-H "Authorization: Bearer $THINNESTAI_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"agent_id": "agent_hindi_support",
"to": "+919876543210",
"metadata": {
"customer_id": "cust_123"
}
}'from thinnestai import Thinnest
client = Thinnest(api_key="YOUR_API_KEY")
call = client.calls.create(
agent_id="agent_hindi_support",
to="+919876543210",
metadata={"customer_id": "cust_123"},
)
print(f"Call started: {call.id}")import { Thinnest } from "@thinnest-ai/node";
const client = new Thinnest({ apiKey: process.env.THINNESTAI_API_KEY });
const call = await client.calls.create({
agentId: "agent_hindi_support",
to: "+919876543210",
metadata: { customerId: "cust_123" },
});
console.log(`Call started: ${call.id}`);Developer capabilities
REST API
Create agents, start calls, query transcripts and outcomes — everything available over HTTPS. OpenAPI spec published.
Python & JavaScript SDKs
First-class Python and TypeScript SDKs for the server-side. Web client SDKs for browser-based voice widgets.
Webhooks everywhere
Every agent event — call started, transcript updated, tool called, outcome captured, call ended — is a webhook you can consume.
Real-time WebRTC
Low-latency voice over WebRTC for browser widgets. Native SIP for phone calls. Both share the same agent runtime.
Flow versioning
Agent flows are versioned like code. Publish, revert, A/B test, diff between versions — all safe for production.
Full observability
Every call produces a transcript, recording URL, latency breakdown, provider cost breakdown and outcome. Export to your own stack.
What developers build on ThinnestAI
Outbound campaign triggered by a webhook
Your CRM fires an event → ThinnestAI places a Hindi outbound call within seconds → outcome written back to your CRM via webhook.
Inbound support widget on your website
Drop our JS widget into your React / Next app. Users click to talk to a voice agent in their language, over WebRTC, with zero phone number required.
Programmatic agent creation
Create and configure agents via REST — good for multi-tenant apps where each customer gets their own agent.
Custom tool calling
Expose any REST endpoint as a tool the agent can call — database lookups, CRM updates, third-party APIs, anything.
Developer FAQ
Is there a free tier for developers?
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Yes. Sign up for free with welcome credits — no card required. Free tier includes platform-managed Sarvam LLM and STT, so you can build your first agent without bringing any API keys.
What languages do the SDKs support?
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Python and TypeScript/JavaScript are first-class server SDKs. Web client SDKs for browser-based voice widgets. REST API is language-agnostic — use curl, Go, Ruby, PHP or anything that can make HTTPS calls.
How do I connect my own provider API keys (BYOK)?
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Bring your own LLM keys in the dashboard or via the REST API — OpenAI, Anthropic, Gemini and more. STT and TTS run on our own Vega + Aero stack (₹0 platform-side), so there's nothing to configure there. For phone, buy a number from us in a click or bring your own (Twilio or any SIP).
Is there an OpenAPI spec I can generate clients from?
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Yes. The full OpenAPI 3.1 spec is published at docs.thinnest.ai/api-reference. You can generate clients for any language using the standard OpenAPI generator tools.
How do webhooks work?
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Every agent event (call started, transcript updated, tool called, outcome captured, call ended) fires a webhook to your configured endpoint with a signed payload. You can subscribe to all events or a specific subset. Standard HMAC signature validation.
Can I use ThinnestAI from a serverless function?
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Yes. The REST API and SDKs work from any serverless environment — AWS Lambda, Vercel Functions, Cloudflare Workers, Google Cloud Functions. WebRTC widgets use a short-lived token you generate server-side, so your API key never reaches the browser.
What's the rate limit?
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Free tier is 10 requests/second and 5 concurrent calls. Paid tiers scale to 100+ requests/second and hundreds of concurrent calls. Enterprise customers get custom quotas.
Do you have a sandbox / test mode?
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Yes. Test mode calls use the same agent logic but route to a simulated phone with no real telephony cost. Good for CI/CD pipelines and integration tests.
Start building with free credits
No card required. Platform-managed Sarvam on the free tier — you can build your first Hindi voice agent without bringing a single API key.