Automate Accounts Payable and Receivable with Custom APIs

Most small businesses run finance on QuickBooks Online and spreadsheets. When an invoice is paid via Stripe, the process breaks. QuickBooks sees the Stripe payout, but that payout is a batch of multiple payments minus a variable percentage fee. An employee has to manually open the payout record, match each line item to an invoice, calculate the fee, and create a separate expense entry for it. This is slow and error-prone.

For accounts payable, a tool like Bill.com works for standard check runs. But it fails when you have custom approval logic, like requiring two partners to approve any invoice over $5,000 but only one for invoices under that amount. Bill.com's approval chains are rigid. This forces the team back to email threads and spreadsheets to track approvals, defeating the purpose of the tool.

Consider a 20-person consulting firm sending 50 invoices a month. The operations manager spends two full days at the end of each month reconciling Stripe payouts and chasing invoice approvals via email. The data in QuickBooks is 30 days out of date, making real-time cash flow analysis impossible. The risk of a missed decimal point or a miscategorized fee is high.

The structural problem is that off-the-shelf accounting software is designed for generic workflows and has a fixed data model. These tools cannot natively model a business's specific rules for matching batch payments or handling conditional approvals. Their APIs are often rate-limited and do not expose the webhooks needed for real-time automation, forcing businesses into manual, repetitive work.

The first step is to map your entire money-movement workflow, from invoice creation to payment reconciliation. Syntora audits every tool you use, from your bank to your payment processor to your accounting software. We identify the exact points where manual work occurs and design API-driven connections to automate them. You receive a technical diagram showing how data will flow before any code is written.

Based on that map, we would build a central API service using FastAPI. This service would act as the hub for your financial operations. For instance, a webhook from Stripe for a new payout would trigger a function that pulls the corresponding transaction details, matches them against open invoices in a PostgreSQL database, calculates the processing fees, and creates perfectly formatted journal entries. We used this exact pattern for our own internal ledger, connecting to Plaid's API to pull bank transactions daily.

Your delivered system is a private API that runs on cloud infrastructure you control, like DigitalOcean or AWS Lambda. It doesn't replace QuickBooks; it feeds clean, reconciled data into it. The system requires no daily management and runs automatically. You get the complete source code, a runbook for maintenance, and a system built to handle your specific business logic, eliminating hours of manual data entry.