Synthflow

Summary

Synthflow is a voice AI platform for building, testing and running phone agents that handle inbound and outbound calls. It ships its own telephony network, a visual flow designer, a simulation test centre and CRM, SIP and PBX integrations.

Best for: Operations and CX teams at mid-market or enterprise companies who want a visual, no-code way to design and launch phone agents without an engineering ticket.
Not for: Developer-first teams who want to assemble and own every layer of the stack via API with full model choice (see Vapi or Retell AI instead), or anyone who wants a fixed, low-commitment self-serve monthly price.

Captured 2026-09-08 · theagentsindex.com

From: Freethen $30,000/year
Free tier: YesBuilding an agent from templates or from scratch, including call flows, voicemail detection and integrations, costs nothing; launching moves you onto pay-as-you-go billing for the calls and chats conducted. No published PAYG rate.

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What it does

Done-for-you service: PartlyYou run the software, but Enterprise agreements include Synthflow-led implementation, launch and ongoing optimisation.Implementation, onboarding, testing, training, launch support, and ongoing optimizationsynthflow.ai/pricing

How much it does unattended

Runs autonomously: YesAgents answer and place calls unattended, escalating to a human only on triggers you configure.They can ask clarifying questions, offer alternate responses, or escalate to a human. You can control handoff triggers based on failed attempts or…synthflow.ai
Multi-agent: YesSubflows act as specialised agents that a parent flow triggers for individual tasks.Architect modular voice flows with a flexible, API-connected builder. Subflows act as specialized agents that handle tasks independentlysynthflow.ai
Agent permissions: YesFlow logic, approved knowledge sources, end-call reasons and handoff triggers bound what an agent may say or do.Synthflow agents follow defined logic and approved knowledge sources — ensuring compliant, brand-safe replies and zero off-script or hallucinated…synthflow.ai

Which models it runs on

Claude: NoThe agent model selector enumerates OpenAI GPT variants and Synthflow's own LLMs; no Anthropic model is offered.The AI Model selector controls which large language model powers your agent's responses. Available options include: GPT-4o ... Synthflow LLM ...…docs.synthflow.ai/general-configuration
GPT: YesThe model selector lists GPT-4o, GPT-4.1 and multiple GPT-5 variants for agent responses.GPT-4o -- fast, versatile model balancing quality and speed.docs.synthflow.ai/general-configuration
Open models: NoThe published model list contains only OpenAI GPT variants and Synthflow's proprietary LLMs; no open-weight model appears.Synthflow LLM -- optimized for real-time, natural phone conversations. Advanced Synthflow LLM -- strongest reasoning in the Synthflow family, for…docs.synthflow.ai/general-configuration
Model choice: PartlyYou pick the model per agent, but only from Synthflow's list of GPT and Synthflow LLM options.Pick the model that matches your latency, cost, and quality requirements.docs.synthflow.ai/general-configuration

Where you use it

In your editor: PartlyNo Synthflow editor extension; Claude, Claude Code and Cowork can drive the workspace over MCP from where a developer already works.Claude, Claude Code, and Cowork can all manage your Synthflow workspace from a conversation.docs.synthflow.ai/anthropic
On the command line: NoThe deployment channels are enumerated as telephony, WhatsApp, WebSocket, chat, API, Workflows, Zapier and GoHighLevel; Synthflow ships no command-line tool.Deploying your Synthflow AI agent gets it live and ready to take calls or messages. Each deployment path is complementary, so you can enable several…docs.synthflow.ai/deploy-your-agent
In your pipeline: NoThe connector needs an interactive browser sign-in, which the vendor says rules out unattended jobs.The official connector requires an interactive browser sign-in, so it is not suited to CI or scheduled jobs.docs.synthflow.ai/anthropic
In a browser: YesAgents are created, tested and published from a hosted dashboard with an in-product assistant.Aurora is the workspace assistant built into the dashboard. Describe what you want in natural language to scaffold agents, query calls, manage…docs.synthflow.ai/getting-started

Whose machine it runs on

Self-hosted: NoDeployment choice is limited to picking one of three Synthflow-operated clusters at workspace creation.Synthflow operates three clusters. The table below shows where each one stores workspace data and where live processing runs.docs.synthflow.ai/customer-region
Open source: NoSubscriber Terms grant a non-transferable licence to use the software and forbid decompiling it.Synthflow grants to the User during the term of the Agreement a non-exclusive, non-transferable, non-sublicensable license to use the Software for…docs.synthflow.ai/terms-conditions

What it costs to run

How it meters: YesCalls are metered per second and aggregated into billed minutes; chat converts at 5 AI messages per usage minute.Phone calls are measured per second, starting when the human and the AI agent connect and ending when the call terminates. Partial seconds are…docs.synthflow.ai/usage
Free tier: YesYou can build an agent at no cost; charges begin at launch on a pay-as-you-go basis.Yes, you can start and build your AI agent for free using our library of industry templates or build your own. You can design custom call flows, set…synthflow.ai
API access: YesPlatform API with bearer-key auth covers agents, calls, campaigns, knowledge bases and subaccounts.Generate a Synthflow API key under Admin > Workspace Settings > API Keys, send it with Bearer authentication, and follow basic key-management…docs.synthflow.ai/authentication
MCP server: YesA hosted MCP server in three regions exposes agent, call and knowledge-base tools to MCP clients.The Synthflow MCP server lets you use Synthflow directly from the AI tools you already prefer, such as Claude, Claude Desktop, ChatGPT, and Codex.docs.synthflow.ai/mcp-server
Bring your own key: PartlyYour own OpenAI or Azure OpenAI key can power supported models, but the option is enabled per account; telephony can also be your own carrier or SIP trunk.After connection, Synthflow routes supported LLM traffic through your OpenAI account using your API key. Billing and usage limits follow the terms of…docs.synthflow.ai/openai

Buying it for a team

A company can buy it: YesSold as a sales-led annual Enterprise agreement with MSA/DPA and security review.MSA/DPA support, data handling review, workspace controls, and enterprise security reviewsynthflow.ai/pricing
Seat model: NoPricing is scoped on call volume and concurrency, not on seats; workspace members are governed by roles instead.Enterprise contracts start at $30,000 annually. Final pricing is scoped around call volume, concurrency, telephony setup, integrations, security…synthflow.ai/pricing
Pooled budget: YesSubaccounts draw on the parent agency's minute balance and share its concurrency total, with optional caps.Subaccounts share the main agency account's minutes. You can allocate caps with Limits and defaults.docs.synthflow.ai/getting-started
Admin controls: YesAgency admins grant or revoke per-subaccount permissions for actions, agent types, editor options and integrations.If you want to enable or disable specific actions for all or certain subaccounts, you can do that in Admin. For example, you can only allow select…docs.synthflow.ai/manage-subaccount-per…
Audit log: PartlyAPI logs give an audit trail of every request an agent makes, with retention set by plan; no admin-action audit log is documented.API logs: Audit trail of all API requests triggered by your agentsdocs.synthflow.ai/logs
Single sign-on: PartlySAML/OIDC via WorkOS with Okta, Entra ID, Google SAML and Auth0, but only on Enterprise.Single Sign-On (SSO) is available on Enterprise plans only. ... Synthflow uses WorkOS as the SSO infrastructure provider.docs.synthflow.ai/security

What happens to your code

Opt out of training: YesA blanket contractual commitment not to train on customer input or output; published Marketplace templates are the one carve-out.Synthflow does not use Customer Input or Output to train, fine-tune, or otherwise improve its own or any third party’s AI or machine learning models.docs.synthflow.ai/terms-conditions
Data residency: YesChoose a US or EU cluster keeping storage and compute in one region; the legacy Global cluster stores in the EU. Choice is permanent.US and EU keep both storage and compute in a single region. New workspaces should use US or EU unless you are continuing on the legacy Global…docs.synthflow.ai/customer-region
Getting out: PartlyManual CSV export of call logs is available to all; scheduled exports to S3, BigQuery or SFTP are Enterprise-only, and unused minutes carry over only if the agreement says so.If you're an Enterprise client, you can configure daily exports of your call data to destinations of your choice, including Amazon S3, Google…docs.synthflow.ai/export-call-data
Certifications: YesISO 27001:2022, SOC 2, GDPR, HIPAA and PCI DSS v4.0.1, with documents in a Trust Vault.Synthflow is compliant with: ISO 27001:2022, SOC 2, GDPR, HIPAA, PCI DSS V4.0.1docs.synthflow.ai/security

29 sourced claims on this page. Checked 2026-09-03. How we check.

Alternatives

Where we would send a reader instead, in that listing's own words.

Vapi
Developer platform for building, testing and deploying voice AI agents that make and receive phone calls.
Retell AI
Platform for building, testing and deploying AI voice and chat agents on phone, web and SMS, billed per minute.

Filed under

APIAutonomousEnterpriseFree tierGPTMulti-agentNo-code

Sources and updates

The pages we read23

Every fact below comes from the vendor. Nothing here is independently corroborated yet.

Coverage elsewhere4

Updates4

2026-09-03Capabilities · Commercial terms · Free tier
2026-08-31Capabilities · Commercial terms · Free tier · Price
2026-08-23Summary
2026-08-19Summary