AI voice agent platforms
A voice agent listens, thinks and talks back fast enough that a caller doesn't hang up. Under the hood it is speech-to-text, a language model and text-to-speech stitched together with turn-taking, plus a phone line. Vapi, Retell and ElevenLabs host that whole pipeline and let you swap the parts. Bland folds the models into one per-minute rate. Synthflow sells it as an enterprise contract with engineers who build it for you. LiveKit Agents and Pipecat are open-source frameworks: you write the agent in code and run it on your own servers or their clouds. Per-minute prices below are the platform's part of the bill; check whether the LLM, voice and phone line come on top. 7 tools, in the order they appear in the directory. This is not a ranking.
Grouped by job: AI Agent Infrastructure
ElevenLabs Agents
ElevenLabs' hosted platform for voice agents: its own speech-to-text, your choice of LLM or a custom model, 10,000+ voices, a turn-taking model, a visual workflow builder, knowledge bases, tests and A/B experiments. Deploys to phone over Twilio or SIP, a web widget, or iOS, Android, React Native and Unity SDKs. Free plan with 15 call minutes; $0.08 a minute after that, LLM billed on top.
Vapi
Developer platform for voice agents that make and take phone calls: pick the transcriber, model and voice from dozens of providers, build single assistants or Squads that hand callers between specialists, test with simulations and manage config as code from a CLI. $0.05 a minute for Vapi hosting, with providers passed through at cost and $5 of free credit.
Retell AI
Platform for AI phone agents: a drag-and-drop call-flow builder, simulation and regression tests, outbound campaigns, live call monitoring with takeover, IVR navigation and CRM write-back, plus chat and SMS agents. Pay as you go at $0.07 to $0.31 a minute depending on model and voice, 20 concurrent calls included and $10 of free credit.
Bland AI
Voice agent platform for phone calls with one per-minute rate that covers the LLM, speech-to-text and text-to-speech: Conversational Pathways for call flows, knowledge bases, version lock, your own Twilio or SIP trunk, and on-prem or VPC on Enterprise. Start plan $0.14 a minute with no platform fee and no card.
Synthflow
Enterprise platform for AI voice agents on customer calls, sold as one annual contract that covers telephony (Synthflow's own or SIP), CRM and calendar integrations, security review and launch by forward-deployed engineers. SOC 2 Type 2, ISO 27001, HIPAA and GDPR. No free plan or per-minute rate.
LiveKit Agents
Open-source (Apache-2.0) framework for realtime voice and video agents in Python or Node.js: mix any STT, LLM, TTS or realtime model, semantic turn detection, MCP tools, a built-in test framework and phone calls through LiveKit's SIP stack. Self-host the whole stack with the open-source LiveKit server, or deploy to LiveKit Cloud, free for 1,000 agent minutes a month.
Pipecat
Open-source (BSD-2-Clause) Python framework for realtime voice and multimodal agents, maintained by Daily: composable pipelines over WebRTC or WebSockets, 80+ LLM, STT and TTS services, Pipecat Flows for structured conversations, multi-agent handoffs and client SDKs from JavaScript to ESP32. Run it anywhere, or on Pipecat Cloud from $0.01 an active minute.
What it is, where it runs, what a minute costs.
Straight from each vendor's own pages. Plans move often, so the check date is below.
| Tool | What it is | Runs on | Open source | Price |
|---|---|---|---|---|
| ElevenLabs Agents | Hosted voice agent platform built on ElevenLabs' own speech-to-text, 10,000+ voices and a turn-taking model, with a visual workflow builder, knowledge bases, tests and A/B experiments. | ElevenLabs' cloud. Phone over Twilio or a SIP trunk, a web widget, or SDKs for React, iOS, Android, React Native and Unity. CLI and hosted MCP to manage agents as code. | No. | Free: 15 call minutes, 4 concurrent calls. Starter $6/mo (75 min), Creator $22/mo (275 min), Pro $99/mo (1,238 min). Extra minutes $0.08. LLM billed on top; no telephony fee from ElevenLabs. |
| Vapi | Developer platform for phone and web voice agents: choose the transcriber, model and voice per assistant, or chain specialists into Squads. Simulations, CLI and config as code. | Vapi's cloud. Vapi phone numbers, your own telephony or SIP, or embedded in a web app. | No. | $0.05/min Vapi hosting, prepaid, with providers passed through at cost. $5 free credit, 4 concurrent calls and 1 phone number with no package. Pro package has a $999/mo minimum. |
| Retell AI | Platform for AI phone agents with a drag-and-drop call-flow builder, simulation tests, outbound campaigns, live monitoring with takeover and CRM write-back. Chat and SMS agents too. | Retell's cloud, with Retell numbers, Twilio or Telnyx, or your own SIP trunk. On-prem on Enterprise. | No. | Pay as you go, $0.07 to $0.31/min depending on model, voice and add-ons ($0.055/min of that is Retell's voice infra). 20 concurrent calls free, then $8 each a month. $10 free credit. |
| Bland AI | Voice agent platform for phone calls where one per-minute rate covers the LLM, speech-to-text and text-to-speech. Conversational Pathways for call flows, knowledge bases and version lock. | Bland's cloud, on Bland's Twilio at cost, your own Twilio or a SIP trunk. On-prem or VPC on Enterprise. | No. | Start: $0.14/min, no platform fee, no card, 10 concurrent calls, 100 calls a day. Build: $0.12/min plus $299/mo. Telephony billed separately. |
| Synthflow | Enterprise voice agent platform sold with telephony, CRM and calendar integrations, security review and launch by forward-deployed engineers in one contract. | Synthflow's cloud, on Synthflow Native Telephony, SIP trunking or approved enterprise telephony. | No. | Annual enterprise contract scoped to call volume. No free plan, trial or per-minute rate; see vendor. |
| LiveKit Agents | Framework for realtime voice and video agents in Python or Node.js: any STT, LLM, TTS or realtime model, semantic turn detection, MCP tools, tests and phone calls through LiveKit SIP. | Your own servers alongside the open-source LiveKit media server, or LiveKit Cloud with managed deployments, observability and phone numbers. | Yes, Apache-2.0 (framework and media server). | Framework free. LiveKit Cloud Build $0/mo with 1,000 agent minutes and 1 free US number; Ship $50/mo with 5,000 minutes, then $0.01/min. Models billed on top. |
| Pipecat | Python framework for realtime voice and multimodal agents, maintained by Daily: composable pipelines, 80+ AI services, Pipecat Flows for structured calls and multi-agent handoffs. | Anywhere Python runs, over WebRTC or WebSockets, or Pipecat Cloud with Daily WebRTC, SIP and PSTN. Client SDKs from JavaScript to Swift, Kotlin and ESP32. | Yes, BSD-2-Clause. | Framework free. Pipecat Cloud agent-1x $0.01 per active minute, 1:1 Daily WebRTC voice free, PSTN $0.018/min. LLM, STT and TTS billed by their providers. |
Checked 2026-11-01. Sources: ElevenAgents pricing, ElevenAgents docs, Vapi pricing, Vapi docs, Retell AI pricing, Retell AI, Bland pricing, Bland docs, Synthflow pricing, LiveKit Agents on GitHub, LiveKit pricing, Pipecat on GitHub, Pipecat Cloud pricing.
Pick it if.
- ElevenLabs AgentsVoice quality is the product, and you want a free plan to try it before you pay.
- VapiYou want to pick every model in the stack yourself and pay those providers at cost.
- Retell AIYou are building a phone line for a business and want flows, tests and live takeover without writing a backend.
- Bland AIYou want one number per minute that already includes the model and the voice.
- SynthflowYou'd rather sign one contract and have the vendor's engineers build and launch the agents with you.
- LiveKit AgentsYou want the agent in your own code, on your own servers if needed, with voice and video over WebRTC.
- PipecatYou write Python and want an open pipeline you can rearrange piece by piece, hosted anywhere.
Each listing.
The directory page, alternatives in the same category, and a head-to-head where we have one.
- ElevenLabs AgentsAlternatives
- VapiAlternatives
- Retell AIAlternatives
- Bland AIAlternatives
- SynthflowAlternatives
- LiveKit AgentsAlternatives
- PipecatAlternatives
Category pages list every tool in that category, including ones left off this page. Built one of these? Get it featured in its category.
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