# Patter

> Open-source voice-AI SDK. The Vapi/Retell alternative for builders who want to own the stack.

## Facts
- **Category:** [Voice Agents](https://agentsearchengine.app/category/voice-agents)
- **Type:** SDK / library
- **Pricing:** Open source
- **GitHub stars:** 1,022
- **Language:** Python
- **License:** MIT
- **Last repo activity:** 1 day ago (Aug 2, 2026)
- **Official site:** https://getpatter.com
- **Source code:** https://github.com/PatterAI/Patter
- **Listing on Agent Search Engine:** https://agentsearchengine.app/agents/patter
- **Data verified:** July 2026

## About Patter
Patter is the open-source SDK that gives your AI agent a phone number. You build the agent; Patter handles everything between it and the phone network — the agent loop, the language model, speech-to-text, text-to-speech, real-time voice, audio processing, and the telephony carrier. Patter is the full voice stack between your application and the phone network — not just glue between an LLM and a carrier. It runs the agent loop and owns every layer of the call, and you pick the provider for each one. Compose them in Realtime, Pipeline, or Hybrid mode. On top of the stack: an automatic LLM fallback chain (provider failover mid-call), built-in tools / call transfer / guardrails that behave identically on every carrier, and a vendor-neutral OpenTelemetry trace of each call.

_From the project's README._

## Install

```
npx skills add patterai/skills
```

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