Jonathan Feller

Working with flagship clients and stealth startups. More on my Toptal profile page.

Individual clients and/or rates are confidential; thank you for your understanding.

I started my own company as more and more people wanted me to work on custom projects, and I needed to have official contracts in place.

Worked on the full-stack development of web apps and customized solutions.

Led the discovery phase for multiple projects, talked to clients, and defined product requirements, architecture and proposals, all the way to the finished project.

Worked on very customized projects for flagship clients like ABInBev and Pearson

Responsible for creating web platforms and applications from the ground up, handling full-stack development.

Restructured existing APIs to adhere to RESTful best practices.

Enhanced the quality of legacy code.

Constructed and managed a tool for integrating and migrating data between the outdated monolithic database and a modern cloud-based distributed database.

Transferred business logic and features from the legacy software to the new cloud-based ERP.

Took charge of developing a tax engine as a service, ensuring responsive performance despite handling multi-million parameters.

Shout out to Carlos Grahl and Tiago Emil

Initiated the creation of the Corporate Tax Module entirely from the ground up.

Formulated the tax calculation procedure, significantly reducing processing time to a fraction of the time from the legacy application.

Authored a migration tool facilitating the seamless transfer of data from the legacy software to the new system. Successfully integrated the Corporate Tax Module with other existing modules.

Shout out to Andre Poffo

Contributed to the development of the revenue module within the city town hall software, focusing on tax calculations for property and land taxes.

Played a key role in integrating third-party systems for report generation.