FINTECH / SAAS
Headless Integration for Legacy Accounting Systems
We built a Python middleware to automate financial workflows on platforms with no official API, using browser automation and reverse engineering.
A US startup needed to integrate data from a well-known legacy accounting platform into their own product. No public APIs existed for the required workflows, and anti-bot systems made a standard integration impossible. The goal was a technical bridge that could automate operations without putting user accounts at risk.
We structured the work in two phases: a 3-week PoC to confirm technical feasibility, then 2 months to production. We used SeleniumBase to handle authentication, building a session persistence layer that minimises logins and makes the automation look like organic traffic. To maximise efficiency, we reverse engineered the software's internal network calls, bypassing DOM interaction wherever possible. The whole architecture is Dockerised and stateless, allowing horizontal scaling of parallel sessions with granular log monitoring.
The result is a performant API service that turns a closed platform into a flexible backend. The startup can now offer advanced fintech features in a fully automated way. We delivered a solid, independent asset — full code ownership with the client, infrastructure they can scale on their own terms.