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Starting a software business with no funding and no team sounds impossible. Yet, in under two years, Mac Martine built and soldCastanet, a LinkedIn outreach automation tool, for seven figures. He did it by focusing only on what mattered—talking to people, rapid iteration, and then getting others to sell the software for him. In this case study, we break down how he moved through three distinct phases to hit $60K in monthly recurring revenue (MRR) with just $3K in expenses.
Mac didn’t start with a big advertising budget or fancy cold emails. He tapped into his existing network—friends, ex-colleagues, acquaintances—and set up casual coffee chats. His goal wasn’t to pitch; it was to understand real-world pain points around LinkedIn outreach. Taking detailed notes, he asked each contact who else he should speak to next. Warm introductions rolled in, and in a few weeks he spoke with over 50 people without any cold blasting.
Armed with real feedback, Mac built a minimum viable product (MVP) in four weeks, focused only on the core feature set prospects had asked for. Re-engaging his highest-potential warm leads, he gave personalized demos tailored to each use case. By delivering real, immediate value, he was able to convert those five initial customers and validate his idea.
With five customers paying, Mac shifted to optimize product-market fit. He started cold messaging potential users on LinkedIn, but framed his outreach as a request for feedback rather than a sales pitch. He offered free demos in exchange for honest input. Each demo call became an opportunity to refine messaging, pricing, and onboarding workflows.
He personally onboarded every new client, observing actual usage versus stated needs. This hands-on approach helped him focus only on features customers would pay for, ignoring vanity metrics. By the time he hit 50 customers, Castanet was pulling in about $10K MRR and had a documented, repeatable sales process ready for take-off.
Moving from $10K to $60K MRR required leverage—Mac couldn’t pitch every prospect himself. He built an affiliate and reseller program, creating marketing kits, demo accounts, and discounted tiers for partners. This gave individuals and agencies a financial incentive to promote Castanet to their own networks.
Soon, dozens of partners were closing deals on his behalf. Castanet’s growth became a matter of supporting and managing that partner base instead of doing all the outreach solo. By the time Mac sold the business, affiliate-driven revenue made up 76% of total MRR.
Castanet’s journey from zero to $60K per month shows that you don’t need big funding or a big team to build a profitable SaaS. You need direct customer conversations, laser focus on what users will pay for, and creative distribution through affiliates. By following the three-stage framework—first customers, optimizing fit, and then building leverage—you can replicate this success in your own venture.
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