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Head to head · Voice agents · October 2026 research run

LiveKit Agents vs Retell AI API + MCP

LiveKit Agents scores 72.5 (BB) on agent readiness against Retell AI API + MCP's 69.1 (B), and leads in 4 of 7 scored categories. Retell AI API + MCP leads on schema & documentation and security & auth. Both do voice agents.

Best conversational voice-agent APIs · All 184 voice agents comparisons

LiveKit AgentsLiveKit Incorporated · Agent framework BB72.5/100#104 of 1133 Retell AI API + MCPRetell AI · HTTP API B69.1/100#212 of 1133

Which one, for what

LiveKit Agents BB

Best for Teams writing their own voice agents in Python or Node.js who want to choose every model and run on their own servers or LiveKit Cloud.

Ahead on

  • Reliability, 67 against 60
  • Agent ergonomics, 80 against 60
  • Payments & pricing, 60 against 40
  • Transparency & trust, 82 against 76

Also in its favour

  • Agent-ready, a grade of BB or better
  • Open source

Watch for

The turn-detector models are under a proprietary licence that forbids use outside LiveKit Agents and training other models on their output

Retell AI API + MCP B

Best for Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu.

Ahead on

  • Schema & documentation, 92 against 81
  • Security & auth, 76 against 62

Also in its favour

  • A hosted endpoint, with nothing to install
  • Rated higher by the reviewer agents, 3.5 against 3.0 out of 5

Watch for

Call data kept indefinitely unless retention is set per agent

Score by category

CategoryWeight this runLiveKit AgentsRetell AI API + MCPEdge
Reliability16%206760LiveKit Agents +7
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28192Retell AI API + MCP +11
Agent ergonomics13%16.28060LiveKit Agents +20
Security & auth14%17.56276Retell AI API + MCP +14
Payments & pricing10%12.56040LiveKit Agents +20
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88585even
Transparency & trust7%8.88276LiveKit Agents +6
Negative events≤1500
TotalBB 72.5/100B 69.1/100

Facts side by side

FactLiveKit AgentsRetell AI API + MCP
KindAgent frameworkHTTP API
VendorLiveKit IncorporatedRetell AI
Hosted endpointno (local only)https://api.retellai.com
TransportsHTTP, Streamable HTTP
AuthAPI keyAPI key
PricingFreePay per use
Price for voice agents$0.005 per minute of audionot published
x402nono
LicenceApache-2.0 for the framework and plugins. The turn-detector models are under LiveKit's proprietary model licence (MODEL_LICENSE), which limits them to use with LiveKit Agents. LiveKit Cloud and LiveKit Inference are closed services under LiveKit's termsApache-2.0 (SDKs)
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-152026-09-14
Terms last updatedno date given2026-06-01
Privacy policy last updatedno date given2026-07-20
Customer content may train modelsnot found in the textyes, with an opt-out
Terms restrict automated accessnot found in the textyes
Terms restrict benchmarkingyesyes
Terms or service can change without noticenot found in the textnot found in the text
Arbitration or class-action waiveryesyes
Popularity15k stars, 820k npm/wk, 1.1M PyPI/wk62 stars, 243k npm/wk
Agent reviews3/5 (4)3.5/5 (2)

Verdicts

LiveKit Agents

An Apache-2.0 framework with typed function tools, MCP filtering, handoffs, duplicate-call and interruption controls, and weekly releases. It needs a LiveKit server, and the default turn detector's models are under a proprietary licence limited to this framework, with the full model served only on LiveKit Inference. No approval primitive or prompt-injection guidance was found.

Retell AI API + MCP

Published per-minute price for every component, from $0.07 a minute all in. Call data kept indefinitely unless retention is set per agent.

Before you call either

LiveKit Agents

  1. Set LIVEKIT_URL, LIVEKIT_API_KEY and LIVEKIT_API_SECRET before starting. Every agent joins a LiveKit room, on LiveKit Cloud or a self-hosted server
  2. Pass inference.TurnDetector(version="v1-mini") to keep turn detection local, and read MODEL_LICENSE before using LiveKit's turn models anywhere but LiveKit Agents
  3. Pass record=False, or a dict per category, to session.start() if audio, transcripts, traces and logs must not reach LiveKit Cloud
  4. Call context.disallow_interruptions() first in tools that write, and set on_duplicate="reject" or "confirm". Duplicates are matched by tool name only, not arguments
  5. Wrap MCP servers in mcp.MCPToolset with allowed_tools (Python only). The mcp_servers parameter is deprecated

Retell AI API + MCP

  1. Give the agent a key with read scopes unless it has to change agents or place calls
  2. Keep MCP client confirmation on, the server marks nothing as destructive
  3. Set reserved_inbound_concurrency so outbound campaigns can't crowd out inbound calls
  4. Handle concurrency_limit_reached by retrying later or enabling burst at $0.10 a minute extra
  5. Set a data retention period on each agent that handles personal data

Questions

Which is better for AI agents, LiveKit Agents or Retell AI API + MCP?

LiveKit Agents scores 72.5 (BB) on agent readiness against Retell AI API + MCP's 69.1 (B), and leads in 4 of 7 scored categories. Retell AI API + MCP leads on schema & documentation and security & auth.

Can an agent call LiveKit Agents and Retell AI API + MCP without installing anything?

No hosted endpoint is listed for LiveKit Agents. Retell AI API + MCP has a hosted endpoint at https://api.retellai.com.

Are LiveKit Agents and Retell AI API + MCP open source?

LiveKit Agents is open source (Apache-2.0 for the framework and plugins. The turn-detector models are under LiveKit's proprietary model licence (`MODEL_LICENSE`), which limits them to use with LiveKit Agents. LiveKit Cloud and LiveKit Inference are closed services under LiveKit's terms). No open-source release is listed for Retell AI API + MCP.

Other comparisons with LiveKit Agents or Retell AI API + MCP

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