OpenAI Realtime API

OpenAI's speech-to-speech API for low-latency voice agents over WebRTC, WebSocket or SIP, with tool calling, MCP servers, interruptions and handoffs.

Category: APIs
Website: https://developers.openai.com/api/docs/guides/realtime
Docs: https://developers.openai.com/api/docs/guides/realtime
Status: active
Pricing: paid
License: proprietary
Maintainer: OpenAI
Added: 2026-10-23
Updated: 2026-10-23
Last verified: 2026-10-23
Submitted by: agentica-curator

Description

The model works directly on audio, keeps conversation state and calls tools. Typical browser flow: your server mints an ephemeral client secret (POST /v1/realtime/client_secrets), the frontend opens a RealtimeSession from the OpenAI Agents SDK (@openai/agents/realtime) and connects over WebRTC (/v1/realtime/calls); servers can connect over WebSocket. Supports voice activity detection, functions, remote MCP servers and connectors, guardrails and handoffs, plus realtime transcription. The GA interface replaced the beta (drop the OpenAI-Beta: realtime=v1 header). Usage-based pricing per audio/text token; see OpenAI's pricing page.

Agent access

llms.txt: https://developers.openai.com/api/docs/llms.txt
Auth: api-key
Notes: Server-side OpenAI API key; browsers and mobile apps should use short-lived ephemeral client secrets.

OpenAI Agents SDK: Lightweight framework from OpenAI for multi-agent workflows in Python (with a JS/TS sibling SDK).
LiveKit Agents: Open-source Python (and JS) framework for realtime voice and video agents over WebRTC, with STT/LLM/TTS plugins, telephony, turn detection, MCP tools and tests.
Pipecat: Open-source Python framework from Daily for realtime voice and multimodal agents: composable pipelines, 80+ AI service integrations, multi-agent handoffs and client SDKs.
ElevenAgents (ElevenLabs Agents Platform): ElevenLabs' hosted platform for voice and multimodal agents: ASR, any LLM, 10,000+ voices and a turn-taking model, with workflows, tools, telephony, tests and evals.
Vapi: Hosted voice-agent API: build phone and web voice assistants that combine your chosen STT, LLM and TTS providers, with tools, MCP servers, telephony and testing.

Guides & comparisons

LiveKit Agents vs Pipecat vs OpenAI Realtime vs ElevenAgents vs Vapi: building voice agents (Comparison): Five ways to give an agent a voice compared: two open-source realtime frameworks (LiveKit Agents, Pipecat), a speech-to-speech model API (OpenAI Realtime) and two hosted voice-agent platforms (ElevenAgents, Vapi). Covers architecture, hosting, telephony, MCP tools, testing, pricing and license.

Sources

https://developers.openai.com/api/docs/guides/realtime

Machine-readable

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Source file on GitHub (edit via pull request)