1st-time solo founder does 90 interviews in 90 days—closes a $25M Series A 2 years in. | Damien Lewke, Founder of Nebulock

Solo founder's 90 interviews lead to a $25M Series A

Nebulock is a cybersecurity company built on the claim that detection should be proactive by default, catching what deterministic tools throw away. Damien Lewke founded it alone and reached a $25m Series A two years later by treating customer discovery as the roadmap, letting 90 interviews in 90 days kill a planned system and redirect the architecture. Design partners that all converted into paying customers carried it to revenue.

Takeaways

• Ninety interviews in ninety days reshaped the product. Lewke emailed security leaders with messages under 50 words and got a response rate above 70 percent. The calls changed key parts of Nebulock's architecture and showed a system he planned to build was unnecessary, while confirming the analytical layer he wanted.
• Every design partner became a paying customer. Nebulock ran a year of design partnerships before its first revenue in the fall, asking for 30-minute weekly commitments. Iterating through those partners produced a repeatable proof-of-concept process, and Lewke waited until revenue looked like a no-brainer before starting to sell.
• Fortune 500 POC closed in six weeks. Inside a company with hundreds of thousands of employees, Nebulock surfaced a finding in a day and a half that no other tool caught, and it escalated to the chief information security officer. By the March deal, the POC asked two hours of customer time.
• Stalled POCs trace back to procurement and expectations. Lewke failed to set expectations about POC length and never mapped the path to close through procurement. One customer loved the POC and wanted to buy, but the deal sat in a procurement black hole because his champion could not push it through.
• Fundraising ran on a 30-page manifesto. Decibel led a $2.4m pre-seed in mid-2024 and Bain Capital Ventures led a $6.1m seed at the end of 2024, for $8.5m total. Lewke wrote a manifesto instead of a pitch deck, and the seed investor came inbound.
• Nebulock bets detection should be proactive by default. Security is inherently reactive, so Lewke built detection that surfaces what deterministic systems discard. Machine learning on command lines caught an OpenClaw agent touching a production database, with raw telemetry analysis and research agents as two more axes. Nebulock has run over 300m agentic investigations.
• Hire one well-placed person over four poor ones. Nebulock's first head of engineering arrived when it was nine people and still in stealth, with Lewke acting as engineering manager and salesperson. He hires for the fires, adding people while the business is growing, not after everything breaks.

The discovery call structure