Building an Industry-Leading Invoice Platform from Zero to a 9-Figure Exit

When the project began, the constraints were daunting: a hard 3-month deadline to go live, no established design system, and building from absolute zero.

The team needed to create a complete invoice processing workflow that would serve multiple user roles with fundamentally different needs—from employees submitting invoices to finance teams managing complex approval flows.

The Approach

• Strategic Mapping: We began with internal Subject Matter Expert (SME) interviews to define four distinct user roles: Submitter, Invoice Reviewer, Manager, and Finance.
• Feature Prioritization: Card sorting was used to ensure the most critical features were built for the MVP while less vital ideas were moved to the roadmap.
• Design system: Best way to move fast is to build infrastructure first. Instead of a full design system I opted to build just the necessary component library.
• Rapid Iteration: We implemented improvements immediately after each session, completing 8 full iterations in the time it would usually take for one.

The Lean UX Gamble

Faced with an impossible timeline, the team abandoned traditional UX methodology. Instead of running 5–10 tests before implementing changes, we adopted an aggressive iteration strategy: test one user, implement improvements immediately, then test again.

The trade-off was real. With a sample size of one, some changes actually made the experience worse. But vigilant monitoring made these missteps easy to spot and reverse. The payoff? Eight complete iterations in the time it would normally take to complete one cycle.

This approach transformed a potential failure into a dramatic success: the MVP launched on time, the product became an industry leader within 18 months, and contributed to a nine-figure acquisition.

Understanding the Problem Space

Through discovery sessions with subject matter experts, the team identified 5 distinct user roles, each with competing priorities:

• Submitters needed simplicity: just upload an invoice and get it paid.
• Suppliers want to get paid quickly and notified if something goes wrong.
• Reviewers needed precision: verify supplier matches, validate amounts, catch AI errors, and handle complex scenarios like split single line item to multiple cost objects.
• Managers needed control: to see everything affecting their department, check for duplicates across the entire system, and approve or reject with context.
• Finance needed flexibility: change virtually any field except total amounts, reroute invoices when needed, and ultimately get everything booked and paid.

Prioritization Through Card Sorting

Rather than guessing at feature importance, the team ran a comprehensive card sorting exercise that revealed a clear truth: start with headers, defer the details.

The MVP would focus on header-level information—supplier name, dates, amounts, purchase orders—and a robust document viewer. The entire line items category, despite being important, was explicitly marked "not MVP." This ruthless prioritization allowed the team to ship a working product that solved the core workflow, with granular itemization planned for phase two.

Design system in 12 hours

Moving fast requires solid design infrastructure, but the deadline left no room for a full system. So I put in a 12-hour day and built the minimal set of components we actually needed, all in one sitting. That foundation was enough to iterate quickly and run through multiple prototypes. After launch, we went back and built a proper design system from scratch — you can find that in a separate case study.

Design Iterations That Mattered

The team tested radically different layouts:

• Image on the right (failed—cut off line items)
• Invoice page as modal (tested)
• Full-screen modal approach (tested)
• Line items below at full width (tested)
• Action buttons in header vs. sidebar (evolved)

Initially, we tried an invoice modal with the image on the right, but line items were frequently cut off.

Full screen modal with image on the right performed better because it gave more space but we still had line items cut-off issues on smaller screens.

Image on the left gave us more space for line items. But action buttons were not easily visible at the bottom, especially in case of more line items. Also multi page invoices required additional click to view next page.

Sections as accordions solved some issues with space but introduced new ones by making content less discoverable. Making multi page invoices scrollable was great improvement.

At this point we had better understanding on which sections are important so we moved them to the top and out of accordions.

Final design: Action buttons in header with line items below at full width. We moved secondary content from accordions to tabs, making it discoverable and accessible without overloading the users.

What Real Users Revealed

The testing phase uncovered insights that would have been impossible to predict:

• The 80% Problem: A head of finance at a bank shared a startling statistic—80% of overdue invoices were overdue because they simply weren't uploaded on time. The solution wasn't better approval workflows; it was making due dates mandatory and sending reminders before invoices even entered the system.
• The Approver Flexibility Gap: Users needed to change approvers at the invoice level because the same vendor might need different approval chains depending on what they were buying. A website development invoice needed different approval than a maintenance invoice from the same supplier.
• The Power User Insight: One participant's feedback exposed a critical gap: "It would be nice to access all information in a table. As a power user, when there's a revision coming in, I need to look up invoices quickly."Different users needed different views. Submitters needed simplicity. Finance teams processing hundreds of invoices needed speed and data density.
• The Comment Visibility Problem: Comments were buried in history, forcing users to dig for context. As one tester put it, comments are "used for communication and paper trail"—they needed to be front and center.