During July 2025, Egutierrezduthiers enhanced the invopop/gobl repository by implementing comprehensive validation for Brazilian tax identification numbers. Focusing on backend development and tax compliance, they introduced validation logic for both CPF (11 digits) and CNPJ (14 digits) using checksum algorithms in Go. This work ensures that Brazilian tax IDs are accurately verified during data ingestion and processing, directly supporting regulatory requirements and improving data integrity. By expanding the system’s validation coverage, Egutierrezduthiers reduced the risk of downstream errors and facilitated smoother onboarding for Brazilian entities, demonstrating depth in backend engineering and a strong understanding of compliance-driven development.