I built a tiny tool for the problem every BNPL app hides: the stack

Every buy-now-pay-later (BNPL) app is designed to calculate exactly what you owe them, yet none of them reveal the more pressing question: what you owe to everyone else and when. When you use a combination of apps like Klarna, Afterpay, and Affirm, you end up with multiple dashboards, varying payment schedules, and due dates. While each app is individually honest, the overall picture is obscured, leading to the creation of BNPL Stack Untangler, a free web tool that simplifies this process.

To use the tool, you input each of your BNPL plans separately, providing details such as the provider, the item purchased, the installment amount, the number of remaining payments, and the due dates. BNPL Stack Untangler then generates a single view that displays the total amount you owe across all plans, what is due this week and month, and a calendar showing all upcoming installments from all providers. The tool highlights weeks where several payment cycles coincide, indicating potential issues if payments are delayed.

One of the key design choices was to avoid creating an account barrier; the tool's purpose is to provide an immediate reality check without the need for registration. Additionally, the tool does not integrate with any BNPL provider's API, as the transaction stack is not limited to a single provider. Instead, users input their own lists of plans, making the tool universally applicable.

The tool's guides provide detailed information on fees and plan differences for each provider, allowing the main interface to remain uncluttered.

The most significant challenge in developing the tool was not the mathematical calculations, but rather determining the optimal calendar view. The failure of BNPL plans typically occurs in a specific week when multiple payment cycles align, and any tool that solely focuses on totals without providing a timeline misses this critical failure mode. BNPL Stack Untangler addresses this by offering a comprehensive view that includes a timeline, ensuring users can effectively manage their BNPL obligations.

For those juggling multiple BNPL plans, BNPL Stack Untangler is available for free at https://bnplstackuntangler.com. The creator is eager to receive feedback on how users visualize their financial stack to further improve the tool.