Synthflow

Synthflow is a managed, cloud-hosted AI voice-agent platform for enterprise phone automation. Teams can configure agents for inbound and outbound calls, embeddable voice experiences, and use cases such as appointment scheduling, lead qualification, reminders, routing, data collection, and support triage. Chat agents can also be delivered via API, widget, SMS, or WhatsApp.

It is a workflow platform rather than a standalone text-to-speech API: agent building, retrieval, actions, handoff, simulations, analytics, and exports are part of the product. Enterprise contracts start at $30,000 per year.

Synthflow offers two conversation-building approaches. Prompt Builder suits simpler, open-ended Q&A and rapid prototypes, while the visual Flow Designer gives teams node-based control over collection, branching, jumps, booking, transfers, actions, and call completion.

Conversation variables can feed prompts, branches, external actions, transfers, SIP headers, SMS, and webhooks. Knowledge bases can use imported Zendesk Help Center articles for retrieval-backed responses, and the platform supports speech recognition, text-to-speech, and interactions in 50+ languages. For complex work, its guidance favors splitting behavior between multiple agents or using Flow Designer instead of loading a single agent with more than 20 tool calls.

Reusable and custom actions let agents transfer live calls, make HTTP requests, exchange messages during calls, book time, and extract fields. Custom HTTP actions support GET, POST, PUT, PATCH, and DELETE with configurable authentication, headers, payloads, variables, and result handling.

Telephony coverage includes inbound calls, outbound batch calling, SIP/PBX connectivity, and warm or cold human handoffs. Batch calls can be scheduled with concurrency controls and weekly calling windows, for up to 1,000,000 recipients per batch. Transfers can target phone numbers, SIP URIs, dynamic destinations, or conditional phone books; in-call SMS and WhatsApp can also pass information into later workflow logic.

Test Center supports repeatable scenario simulations with success criteria, pass/fail explanations, transcripts, recordings, and run history. This is useful for regression-style checks, but transfers and real-time bookings are represented in transcripts rather than executed during simulations.

Runtime tooling includes analytics for volume, duration, status, end reasons, performance, actions, and sentiment; call, chat, API, and webhook logs; live monitoring; CSV exports; and post-call webhooks. Analytics refresh hourly. Enterprise teams can export daily call data to Amazon S3, Google BigQuery, or SFTP. Recording and transcript retention can be disabled or set to 30 days, and listed PII can be redacted, though redaction is not retroactive, does not affect live audio, and may not be fully accurate.

Synthflow is ideal for organizations with recurring customer phone workflows and a need to connect voice automation to CRM, calendars, telephony, contact centers, or SIP/PBX systems. It’s a great fit for contact centers, BPOs, healthcare operations, agencies, white-label partners, CRM or SaaS vendors, and enterprise operations teams.

It’s less suited to buyers looking for a basic text-to-speech API, a low-cost static auto-attendant, or a small self-serve package. The sales-led enterprise model, starting at $30,000 annually, makes deployment scope and integration requirements central to the buying decision.