Stay up to date with the latest changes to Synthflow.
Faster navigation is now available to all workspaces, following its early-access debut in May. Page transitions that used to take 2 to 3 seconds now load in about 0.6 seconds.
Select ElevenLabs V3 as your voice model, then use audio tags in agent prompts and flow messages to control accent, tone, and delivery.
Global tags keep one voice character for the entire call. Situational tags adjust delivery at a specific moment in a message.
Catalan, Slovenian, and Welsh join the full list of available languages you can assign to agents.
Create and update assistant requests now accept the speech-to-text fields from the assistant editor.
Configure transfer office hours on LIVE_TRANSFER actions through create and update requests.
Assistant and action detail endpoints accept optional query parameters to include related IDs. Relationship fields stay empty by default.
Configure how each input variable is collected per assistant attachment, so one shared action can use different variable sources on different agents. Action placeholders and mapping explains the mapping options in the product UI.
The websocket endpoint below, used for custom website and app integrations, will be deprecated on June 15, 2026. After this date, the endpoint will no longer be available.
This change only affects integrations that connect directly to the websocket endpoint above. If you are using the Synthflow Widget embed, you are not affected. Widgets will continue to work as expected.
Migrate to the Synthflow Widget embed before June 15, 2026.
When you configure an MCP server, you can add Headers and Query parameters as key-value pairs. Use them for API keys, tenant IDs, or other values your server expects on every request.
See MCP Connectors for setup steps.
When an action needs an input variable, you can now choose how Synthflow should fill the value: collect it from the caller, use an action output, use a system variable, use a pre-call variable, or enter a fixed value.
Action placeholders and mapping explains how input variables work across actions.
If an action used during a call is deleted later, the call details will now show a deleted-action placeholder instead of removing it entirely.
Connect Synthflow agents to external MCP (Model Context Protocol) servers, giving the LLM access to tools it can invoke during calls.
Follow the MCP actions guide to connect a server via UI and via API, and choose the tools your agent can use.
Synthflow now includes an early-access improvement that reduces delays when switching between pages. It changes how app sections load, making navigation feel more responsive and significantly smoother.
You can enable the feature from Early Access and disable it at any time. If you notice anything unexpected or have feedback, share it with the Synthflow team so we can continue improving the experience before general release.
You can now reference an existing phone book in call transfer actions with phone_book_id, bringing the API in line with the UI.
Synthflow TTS is now available as a voice model option in the agent editor. It delivers low-latency, natural-sounding speech across 32 languages with 12 built-in voices.
The GET /voices endpoint now supports search and provider query parameters for filtering, and voice responses include provider, gender, and languages fields.
You can now assign multiple outbound phone numbers to one agent and choose the caller ID for each outbound call. See the Outbound Number Pooling guide.
You can now update existing knowledge base sources by source ID. The endpoint supports name, url for link and file sources, and content for text sources.
Nothing was removed, we just cleaned up where things belong. The page that used to be called Contacts in the left-hand sidebar is now Memory, which better describes what it actually holds: the long-term knowledge your agents reuse across calls.
Phone books now live inside Call Transfers, so they sit alongside the rest of your call-handling tools instead of in a separate area of the app. You’ll find them in the same place you configure transfer destinations, no need to switch sections to manage routing.