OpenAI Realtime API alternatives

OpenAI's Realtime API for native speech-to-speech multimodal interaction with GPT-4o — launched Oct 2024 (DevDay). Skips the STT → LLM → TTS pipeline by passing speech directly to GPT-4o. Full OpenAI Realtime API record →

  1. 1 Pipecat (Daily) Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 17k released 2026-08-01 BSD-2-Clause Compare with OpenAI Realtime API →

  2. 2 LiveKit Agents Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also self-hostable · also offered managed

    OSS ✓ Self-host ✓ Managed ✓ MCP ✓ ★ 13k released 2026-08-27 Apache-2.0 (framework); turn-detector models… Compare with OpenAI Realtime API →

  3. 3 Bland AI Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also self-hostable · also offered managed

    OSS ? Self-host ✓ Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

  4. 4 Cartesia Sonic Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also self-hostable · also offered managed

    OSS ? Self-host ✓ Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

  5. 5 ElevenLabs Conversational AI (now ElevenAgents) Voice agent platforms ⚠ renamed — now ElevenAgents

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also offered managed · also has MCP

    OSS ? Self-host — Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

  6. 6 Retell AI Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also offered managed · also has MCP

    OSS ? Self-host — Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

  7. 7 Vapi Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also offered managed · also has MCP

    OSS ? Self-host — Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

  8. 8 CallRail Conversation Intelligence Voice agent platforms

    also in Voice agent platforms · same storage (kv) · same retrieval (injection) · same conflict handling (stateless) · same memory unit (turn) · also offered managed · also has MCP

    OSS ? Self-host — Managed ✓ MCP ✓ Compare with OpenAI Realtime API →

Ranked by shared memory design (storage, retrieval, conflict handling, memory unit), same section and shared must-haves (open source, self-hosting, MCP), with adoption as a tie-breaker. ✓ confirmed · — no · ? not in the catalog yet. Want picks for your own requirements? Use the chooser. Checking a whole project? Check your stack.