Partner spotlight: StackOptimise

Felix and Penn Frank are brothers, and before they built StackOptimise they spent a combined 15 years carrying sales bags — SDR to AE to Head of Sales at companies like Deliveroo, Confluent, and Monzo. StackOptimise is what they built with that experience: a signal-based outbound agency. The spiky part is what they did next — they turned the playbook into products.

StackOptimise is an OutboundSync agency partner, and they run outbound on the platforms OutboundSync supports, so we’ve seen the work up close.

Who’s behind it: Felix and Penn Frank

StackOptimise is run by two brothers, Felix and Penn Frank, and the detail that matters is where they came from: the sales floor. Between them they spent about 15 years going SDR → AE → Head of Sales at companies like Deliveroo, Confluent, and Monzo before starting the agency in 2024. That’s a different starting point from most outbound shops, which tend to be run by marketers — the Franks learned what actually books meetings by having to book them themselves.

The spiky part: they productized the playbook

Plenty of agencies run campaigns. StackOptimise took the system it runs for clients and turned it into things you can buy without hiring them. There’s StackSplit, an AI-driven split-testing tool for finding message-market fit; $1M Messages, a swipe file of outreach templates mined from a database of more than four million sent messages; and a pair of courses — the GTM Engineer course they bill as the first of its kind, and a GTM Agents course that teaches non-technical operators to build AI agents with Claude Code, n8n, and Make. A 7,000-subscriber newsletter sits on top of all of it.

The reason that matters to a client isn’t the products themselves — it’s what they signal. A team that can package its methodology into a teachable course and working tools is a team that actually has a methodology, not just a list and a sending tool.

What StackOptimise actually does

The core is still done-for-you outbound: signal-based targeting across 30+ data sources, personalized copy, and the deliverability infrastructure to land it — and they are certified across Clay, Smartlead, and GetSales, all three. Clients range from startups to names like Multiverse and NetBase Quid, and they report 30–150 qualified leads a month.

The numbers they publish:

The fit with OutboundSync

StackOptimise runs on the tools OutboundSync supports — Clay, Smartlead, HeyReach, Instantly, HubSpot, Salesforce, and a long tail of others — and OutboundSync lands that outbound activity on the right records in the CRM. For an agency running signal-based campaigns across this many systems, clean CRM activity is the difference between a tidy pipeline and a mess.

If you want outbound run by people who have actually carried a quota — and who will teach you the system if you ask — Felix and Penn’s team is worth a look.