The Plaid Engineering Interns for Summer 2019 worked on various projects to improve the company's products and services. Lujing, a MIT student, contributed to webhook verification and client-scoped webhooks, gaining experience with JSON Web Tokens (JWT) and system design. Jarrod, a Rice University student, focused on cloudwatch exporter and gRPC mTLS, acquiring skills in AWS and Docker, as well as Go programming. Sarafina, a UC Berkeley student, worked on city and state transaction data pipeline and transactions enhancement machine-learning service, developing her knowledge of microservices and Python machine learning ecosystem. Andrew, an MIT student, implemented link account subtype filtering and credit card liabilities, honing his skills in integration with other teams and product development. Eric, a Brigham Young University student, improved bank integrations performance by investigating and documenting approaches to reduce network latency, acquiring expertise in reverse engineering and security techniques. Owen, a Harvey Mudd student, added production data replay and bank integration rate limits, learning about design challenges and solving problems independently. Jennifer, a MIT student, implemented digital signatures and transactions data enhancement improvements, developing her skills in public-key cryptography and project planning. The interns also participated in Plaiderdays, an internal hackathon where they worked on projects to improve Plaid's products and services, with some teams winning awards or recognition.