Webhooks, the API and the MCP server

Webhooks (Pro and up)

Under Settings, Integrations, add an Endpoint URL (https) and pick events:

• lead.replied and meeting.booked (ticked by default)
• lead.tagged, lead.accepted, lead.stage_changed, lead.unsubscribed and message.sent

Hollerly sends a JSON POST with the event, the time, your workspace, the lead and event data. Each webhook has its own secret (Reveal, Copy). Every request carries an X-Hollerly-Signature header with an HMAC SHA-256 of the raw body, so you can check it came from Hollerly. Use Send test to try it. If your endpoint answers HTTP 410, the webhook turns itself off. You can have up to 100 webhooks.

API keys (Agency)

Under API keys, enter a Key name and click Create key. Copy it straight away, because it won't be shown again. Send it as a bearer token in the Authorization header. You can have 20 active keys and revoke any of them.

The API lets you list campaigns, add up to 500 leads to a campaign, read leads and replies, update a lead's stage, tags and deal value, and pause or resume campaigns. Full reference: API docs.

Zapier and Make

There's no listed Zapier or Make app. Connect them with an API key: create a REST hook through the API to get events, and call the API to add leads. In Make you can also use the HTTP module. The API docs have the details.

MCP server (Agency)

Hollerly runs an MCP server at /api/mcp on your Hollerly address, using the same API key. AI assistants that support MCP can then list campaigns, read stats and replies, add leads, change a lead's stage, and pause or resume campaigns. For Claude Code, the API docs show the exact command to add it.