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Butter AI is currently in Beta. We are working closely with our early users to refine the platform and build the future of voice AI.
Butter AI is a developer-first platform for building, deploying, and managing human-like Voice AI agents. We built Butter because we were frustrated with existing platforms that lock you into one provider and charge absurd markups. Butter is different: true multi-provider flexibility, transparent pass-through pricing, and powerful enterprise features like vector-based knowledge bases and custom API tools.

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Why Butter AI?

Building voice agents from scratch is hard. You have to manage:
  • Latency: Shaving off milliseconds to prevent awkward pauses.
  • Interruptions: Handling when a user speaks over the bot.
  • Telephony: SIP trunks, WebRTC, and phone number provisioning.
  • Tool Calling: Connecting the AI to your backend systems.
Butter AI handles all of this infrastructure so you can focus on the conversation design and business logic.

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Key Features

Sculpt Your Perfect Agent

Mix and match LLMs (GPT-4, Claude, Gemini), voices (ElevenLabs, OpenAI, Deepgram), and providers. True flexibility, not vendor lock-in.

Feed It Intelligence

Upload PDFs, docs, or plain text. Vector search powered by Pinecone makes your agent an expert on your business.

Extend Powers

Custom API tools. Let your agent check inventory, book appointments, or update CRMs via webhook.

Deploy Anywhere

Bring your Twilio numbers or use LiveKit SIP. Inbound, outbound, transfer—it all works.

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Architecture

At a high level, Butter AI sits between the telephone network and your AI logic.
  1. Call Ingress: We receive calls via Twilio or SIP.
  2. Transcribing: Audio is streamed in real-time to an STT provider (e.g., Deepgram Nova-2).
  3. Reasoning: The transcript is sent to an LLM (with your system prompt + RAG context).
  4. Speaking: The LLM response is converted to audio via TTS and streamed back to the caller.
All of this happens in sub-second timeframes to ensure a natural conversation flow.