Open-source voice agent frameworks
Frameworks for building a program that listens, thinks with a language model, and talks back in real time, over the web or a phone line. You still bring your own speech and language models; the framework wires them together.
A Python framework under BSD-2-Clause, maintained by Daily, for real-time voice and multimodal agents, with the widest provider list on this site and telephony serialisers for Twilio, Telnyx, Plivo, Vonage, Exotel and Genesys.
An Apache-2.0 framework for real-time voice agents that connects any speech, language and voice provider, with semantic turn detection, native MCP tool support, a test framework, and an open-source media and SIP stack it can run on entirely.
A real-time conversational AI framework from Agora with a visual designer, a SIP extension and turn detection, released under Apache-2.0 plus conditions that forbid competing deployments, which makes it source available rather than open source.
Questions people ask
What is the best open-source voice agent framework?
Pipecat (BSD-2-Clause, maintained by Daily) has the widest list of speech, language and voice providers and telephony serialisers for six carriers. LiveKit Agents (Apache-2.0) runs the whole stack, including the media server and SIP service, on your own machines, with semantic turn detection and native MCP tools. Both are Python.
Can open-source voice agents make phone calls?
Yes. Pipecat has serialisers for Twilio, Telnyx, Plivo, Vonage, Exotel and Genesys. LiveKit Agents uses LiveKit's open-source SIP service. TEN has a SIP extension with a Twilio example. Bolna runs on Twilio or Plivo. In every case the phone number comes from a carrier account you set up.
Do I still need a cloud service to run an open-source voice agent?
LiveKit Agents can run entirely on your own servers, including the media server. Pipecat runs locally with any of eight transports. TEN's documented quick start depends on Agora's real-time service. Bolna needs a Twilio or Plivo account and ngrok for calls. The speech and language models are separate accounts unless you run local ones.
Is TEN Framework open source?
Its licence is Apache-2.0 plus conditions from Agora: no hosting on end-user devices, and no deployment that competes with Agora's offerings or lets others compete. That is a field-of-use restriction, so this directory labels TEN source available. Pipecat, LiveKit Agents and Bolna carry plain OSI licences.
Paying for an AI tool you would rather own?
Reveneau sets up the replacement on your own servers, connects it to your product, and builds the software around it.