What is the best alternative to Synthflow?

It depends on whether you'd rather self-host or buy a managed product. xiaozhi-esp32-server is the most widely-adopted open-source alternative (10.0k GitHub stars); Bland AI is one of the commercial options. Compare the full list above on adoption, license, and pricing.

Is there a free or open-source alternative to Synthflow?

Yes. xiaozhi-esp32-server, ten-vad, and bailing are open-source voice agents you can self-host for free — you still pay for the infrastructure you run them on and any model or API usage. See the ranked open-source list above.

How are these Synthflow alternatives ranked?

Every product in the voice agents category is a candidate. Open-source alternatives are ranked by maintained adoption — GitHub stars plus recent commit activity — so you see what's genuinely used, not abandoned. Commercial products are listed separately and alphabetically, because stars don't measure commercial adoption. Sponsored placement is always labeled and never affects the ranking.

Alternatives · Voice Agents

Synthflow alternatives

Looking for an alternative to Synthflow? Below are the voice agents in our index that do a similar job — open-source options are ranked by real maintained adoption (GitHub stars and recent commit activity), never by sponsorship. Synthflow is a commercial product, so the list below includes both other commercial options and open-source projects you can self-host.

28 alternatives · all voice agents · how we rank

The product you're replacing

SynthflowPlatformVoice Agents

No-code AI voice agents for inbound and outbound calls.

Paid product

Visit Synthflow →Full Synthflow record

Synthflow's own profile notes it may not be the right fit if you need deep API-level customization. If that's you, the options below are worth comparing.

Commercial alternatives to Synthflow

Listed alphabetically — GitHub stars don't measure commercial adoption.

Bland AIPlatformEnterprise platform for AI phone calls that sound human.Paid productPaid productVerified ElevenLabs AgentsPlatformConversational voice agents powered by ElevenLabs' leading speech models.FreemiumFreemiumVerified Retell AIPlatformBuild production-ready AI phone agents with ultra-low latency.Paid productPaid productVerified VapiPlatformDeveloper platform for building, testing, and deploying voice AI agents.Paid productPaid productVerified

Open-source alternatives to Synthflow

Ranked by maintained adoption — self-hostable and free to run.

01xiaozhi-esp32-serverInfrastructure本项目为xiaozhi-esp32提供后端服务，帮助您快速搭建ESP32设备控制服务器。Backend service for xiaozhi-esp32, helps you quickly build an ESP32 device control server.JavaScript · 10.0k stars · MIT · Jul 2026JavaScript · 10.0k stars · MITVerified · Active 02ten-vadSDK / libraryVoice Activity Detector (VAD): low-latency, high-performance and lightweightC · 2.2k stars · Feb 2026C · 2.2k stars · Feb 2026Verified 03bailingAgent百聆是一个类似GPT-4o的语音对话机器人，通过ASR+LLM+TTS实现，集成DeepSeek R1等优秀大模型，接入openClaw，真正的个人语音助手，时延低至800ms，Mac等低配置也可运行，支持打断Python · 1.7k stars · MIT · Apr 2026Python · 1.7k stars · MITVerified 04RCLIAgentTalk to your Mac, query your docs, no cloud required. On-device voice AI + RAGC++ · 1.5k stars · MIT · Mar 2026C++ · 1.5k stars · MITVerified 05CyberVersePlatformSelf hosted, real-time digital human agent platform. Build voice-first AI agents with WebRTC, persona memory, tools, RAG, and optional digi…Python · 1.4k stars · GPL-3.0 · Jul 2026Python · 1.4k stars · GPL-3.0Verified · Active 06PatterSDK / libraryOpen-source voice-AI SDK. The Vapi/Retell alternative for builders who want to own the stack. Give your AI agent a phone number in 4 lines…Python · 919 stars · MIT · Jul 2026Python · 919 stars · MITVerified · Active 07rustpbxInfrastructureA PBX written by rustRust · 654 stars · MIT · Jul 2026Rust · 654 stars · MITVerified · Active 08echokit_serverPlatformOpen Source Voice Agent PlatformRust · 588 stars · GPL-3.0 · Feb 2026Rust · 588 stars · GPL-3.0Verified 09StarmoonFrameworkA conversational, AI device + software framework for companionship, entertainment, education, healthcare, IoT applications, and DIY robotic…TypeScript · 549 stars · GPL-3.0 · Mar 2026TypeScript · 549 stars · GPL-3.0Verified 10JARVISAgentYour own personal voice assistant: Voice to Text to LLM to Speech, displayed in a web interfacePython · 524 stars · GPL-3.0 · Jun 2024Python · 524 stars · GPL-3.0Verified 11deepgram-python-sdkSDK / libraryOfficial Python SDK for Deepgram.Python · 447 stars · MIT · Jul 2026Python · 447 stars · MITVerified · Active 12bolnaAgentEnd-to-end platform for building voice first multimodal agentsPython · 433 stars · MIT · Oct 2024Python · 433 stars · MITVerified

Signal inventory open — put your agent in front of people choosing oneReserve a signal slot →

13sutandoAgentMy AI Stand. Realtime by day, rewriting itself by night. Summon my AI superpower.Python · 353 stars · MIT · Jul 2026Python · 353 stars · MITVerified · Active 14LLMVoXSDK / libraryLLMVoX: Autoregressive Streaming Text-to-Speech Model for Any LLMPython · 308 stars · May 2025Python · 308 stars · May 2025Verified 15ai-avatar-systemAgentAI Avatar / digital human platform — upload a photo, clone a voice, talk to any face in real time with lip-sync video. Open-source, self…Python · 295 stars · MIT · Jun 2026Python · 295 stars · MITVerified · Active 16agent-second-brainAgentAn always-on second brain you talk to. Voice notes in Telegram → typed, linked knowledge in your Obsidian vault. Runs 24/7 on the Claude su…Python · 289 stars · MIT · Jun 2026Python · 289 stars · MITVerified · Active 17deepgram-js-sdkSDK / libraryOfficial JavaScript SDK for Deepgram.TypeScript · 266 stars · MIT · Jul 2026TypeScript · 266 stars · MITVerified · Active 18xybridSDK / libraryBuild apps powered by on-device AIRust · 264 stars · Apache-2.0 · Jul 2026Rust · 264 stars · Apache-2.0Verified · Active 19M.I.L.E.SAgentM.I.L.E.S, a GPT-4-Turbo voice assistant, self-adapts its prompts and AI model, can play any Spotify song, adjusts system and Spotify volum…Python · 233 stars · MIT · Dec 2024Python · 233 stars · MITVerified 20gdansk-aiAgentFull stack voice chatbotTypeScript · 199 stars · GPL-2.0 · Oct 2024TypeScript · 199 stars · GPL-2.0Verified 21active-callAgentA SIP/WebRTC voice agentRust · 173 stars · Jul 2026Rust · 173 stars · Jul 2026Verified · Active 22AI-Voice-AgentAgentSelf-hosted AI voice agentPython · 152 stars · MIT · Jun 2026Python · 152 stars · MITVerified · Active 23axiom-voice-agentAgentRun a <400ms latency Voice Agent on just 4GB VRAM. Fully offline, no API keys required. Optimized for GTX 1650 and edge robotics with zero-…Python · 136 stars · Apache-2.0 · May 2026Python · 136 stars · Apache-2.0Verified · Active 24BentoVoiceAgentAgentBuild Phone Calling Voice Agent fully powered by open source models.Python · 124 stars · Apr 2025Python · 124 stars · Apr 2025Verified

Compare Synthflow head-to-head

Frequently asked

What is the best alternative to Synthflow?: It depends on whether you'd rather self-host or buy a managed product. xiaozhi-esp32-server is the most widely-adopted open-source alternative (10.0k GitHub stars); Bland AI is one of the commercial options. Compare the full list above on adoption, license, and pricing.
Is there a free or open-source alternative to Synthflow?: Yes. xiaozhi-esp32-server, ten-vad, and bailing are open-source voice agents you can self-host for free — you still pay for the infrastructure you run them on and any model or API usage. See the ranked open-source list above.
How are these Synthflow alternatives ranked?: Every product in the voice agents category is a candidate. Open-source alternatives are ranked by maintained adoption — GitHub stars plus recent commit activity — so you see what's genuinely used, not abandoned. Commercial products are listed separately and alphabetically, because stars don't measure commercial adoption. Sponsored placement is always labeled and never affects the ranking.