What Stack AI is
Stack AI is a workflow automation tool in the B2B go-to-market stack. In the vendor's own words: “The Middle-Layer of AI.” Put plainly, a tool in this category wires tools together so a result in one becomes an action in another.
Stack AI appears in 2 categories here — Workflow Automation, Customer Service — which usually means it covers more than one job rather than doing a single thing narrowly.
Where it sits in an outbound stack
Most outbound stacks are four layers: the data that decides who you talk to, the channel that carries the message, the writing that earns a reply, and the system of record that remembers what happened. Stack AI sits in the workflow automation layer. Tools beside it are worth comparing on coverage and price; tools in the other layers are worth wiring to it rather than replacing it with.
Using Stack AI with M for Mercury
Stack AI covers a slice of go-to-market that sits next to outbound rather than inside it. Mercury handles the LinkedIn half: audience, journey, message, pacing across senders, and one inbox for every reply. Where the two meet is usually the hand-off — Mercury pushes contacts and events out over webhooks, Zapier, Make, n8n or its own API, so a warm reply can trigger whatever Stack AI is set up to do next.
Questions people ask about Stack AI
What is Stack AI?
Stack AI is a workflow automation tool used by B2B sales, marketing and recruiting teams. In the vendor's own words: The Middle-Layer of AI.
What category does Stack AI fall into?
Stack AI is listed under Workflow Automation, Customer Service in this directory. Its primary category is Workflow Automation.
What are the alternatives to Stack AI?
The closest tools in the same categories are M for Mercury, lemlist, Relevance AI, Artisan, Clay. All 31 workflow automation listings sit on the Workflow Automation category page.
Can I use Stack AI alongside M for Mercury?
Yes. Mercury runs the LinkedIn side — audiences, journeys, message writing, safe pacing across every sender and one shared inbox — and connects out through HubSpot, Salesforce, Zoho CRM, Attio, Slack, Zapier, Make, n8n, webhooks and its own API, so Stack AI can stay exactly where it is in the stack.
Listed for reference. M for Mercury is not affiliated with Stack AI, and no listing here is paid for. Product names and logos belong to their owners.
