How a bootstrapped founder tracks recurring costs before they compound

Vertical: Tech

Mercury products: Insights, IO, Payroll

Founded in 2025 by David Jimenez, a software engineer with over 15 years of experience, Drillby is an online tutoring marketplace where tutors pay a monthly subscription and keep 100% of their earnings.

The idea for the business came to him while searching for a Korean tutor. Jimenez noticed something about the economics that didn’t sit right — not for the tutors, at least. Major platforms were taking up to 30% commission on every class. In some cases, 100% of the first lesson. For someone trying to build a livelihood around teaching, those numbers are hard to reconcile. So he started building the platform he wished existed. Drillby charges tutors a flat monthly subscription without percentage-based commissions or unpaid trial lessons.

His conviction is straightforward: platforms shouldn’t extract wealth from the people who make them valuable. “It’s online tutoring without the platform tax,” Jimenez says.

He runs the project on nights and weekends, while working full-time during the day and self-funding Drillby entirely out of personal savings. Every dollar spent on infrastructure, hosting, design tools, and SaaS subscriptions comes directly out of pocket. The burn rate is lean by any measure. But when every expense is personal capital, financial awareness isn’t just good practice, it’s critical.

When Jimenez first opened a Mercury account to run Drillby’s finances, he started browsing the Insights page out of curiosity. The interface was clean. But what began as an idle look quickly turned operational.

The spending breakdown of his outflows surfaced a subscription that no longer justified its cost. He’d been paying for it for five months, but had only actively used it for two. During the remaining three months, his focus had shifted to development, doing UI/UX adjustments directly while building. That single line item for a tool he wasn’t actively using represented over 8% of his total monthly spend. Excluding Delaware Corp and tax expenses, the share was even higher.

The issue wasn’t really that the cost was hidden. It was that scanning a flat transaction list doesn’t surface patterns.

“When we look at the transaction list, we might just go through it and think, what’s paid is paid. But we don’t exactly know how much everything costs over time, or how much we’re spending in specific categories.”

Insights reorganized the same data Drillby already had into something Jimenez could readily act on, spending grouped by category and vendor, with changes flagged over time.

The second discovery was subtler. Jimenez pays a recurring monthly fee for a virtual business address service. One month, the charge quietly increased, likely because an introductory discount had expired. The bump was small in absolute terms, but when you’re bootstrapping a business, every dollar matters in your monthly burn. He didn’t catch it in his transaction feed. Insights did.

For a solo founder paying out of pocket, a recurring increase that goes unnoticed compounds fast. If a fee is close to 20% of monthly spend, annualized it’s the equivalent of more than two full months of operating expenses. Enough for a contractor sprint, a hosting upgrade, or to extend runway. The alert turned a silent cost creep into a process change.

Drillby doesn’t have a finance team yet, and Jimenez doesn’t plan to hire one anytime soon. His first hire will be someone to work on the product full-time. That’s a common calculus for bootstrapped founders: every dollar needs to work as hard as it can, often competing with product, marketing, or customer-facing headcount growth.

“I have enough visibility to know what to do. I think the priority will be more like a salesperson. I have enough tools on Mercury to handle the finance side myself right now.”

At the moment, Jimenez reviews Insights once a month to track expenses and detect signals related to the services he’s running. But he expects the habit to intensify as Drillby grows. Several parts of his tech stack will scale with usage: database and backend infrastructure as tutors, students, and stored data increase; hosting and bandwidth as application traffic climbs; real-time video classroom infrastructure as lesson volume picks up; and email and notification services as active users multiply.

“Regardless of what third-party pricing pages say, the real cost is reflected in the money leaving my account,” Jimenez says.

What initially drew Jimenez to Mercury was the product design. “The UI/UX feels very aligned with modern startup workflows,” he says. “It’s simple, clear, and gives me a good overview of my company’s finances without unnecessary complexity.” For a solo founder who builds software for a living, that kind of craftsmanship registers. It’s the same attention to detail he’s trying to build into Drillby’s own classroom tools.

Looking ahead, David also sees a banking platform he can grow into. Products like Mercury Capital could make funding more accessible as Drillby scales, and the evolving accounting features mean the financial infrastructure won’t need to be rebuilt later. For now, it’s the right starting point. And for a founder who plans to pay someone full-time before paying himself, that matters.

What started as a casual subscription audit has become an operational rhythm — a financial awareness practice that positions the business to grow without waste.

“When we start a new business, we get pretty excited about everything,” Jimenez says. “It’s easy to spend money on services to build the project and burn through the cash. When we have a main job and we want to build something on the side, cost matters — especially if we want to use that money to pay someone rather than maintaining dormant subscriptions.”

By running every dollar through Mercury and reviewing Insights regularly, David’s been able to:

• Identify and cut a dormant subscription that accounted for over 8% of total monthly spend — before it compounded into months of wasted capital
• Catch a quiet vendor price increase worth ~20% of monthly burn that would have gone unnoticed in a standard transaction list
• Defer a finance hire entirely, directing limited capital toward product development and his first full-time team member
• Maintain clear category-level visibility into all outflows as a one-person operation, with a monthly review habit that scales as costs grow

Drillby early access is now open, and Jimenez anticipates burn to more than double as onboarding and classroom services come online. The plan remains the same though: use incoming revenue to hire someone full-time to build the product — before paying himself a cent.