Gustavo – AWS, Python, React

It's a multi-tenant system that enables accountants, automated services, and end clients to securely store, organize, and exchange accounting, financial, and HR documents.

• Owned end-to-end architecture of a serverless, multi-tenant document platform and implemented most of the backend and frontend.
• Built a clean-architecture FastAPI backend on AWS Lambda with layered design and DI, enabling new operations without touching transport or persistence code.
• Designed polyglot persistence with DynamoDB for low-latency reads/writes and OpenSearch for full-text and faceted search.
• Implemented an event-driven ingestion pipeline (S3 → EventBridge → indexer Lambda) and an immutable audit trail via DynamoDB Streams → Kinesis.
• Built Safe Link Sharing on AWS Durable Lambdas with orchestrated retries and isolated failure semantics, plus async bulk ZIP downloads via SQS.
• Enforced CNPJ-based tenant isolation and Auth0 JWT authorization across all query layers, with API-key fallback for service-to-service calls.
• Provisioned the full AWS stack via CDK in Python, deployed through GitHub Actions, and instrumented with Datadog APM, Mixpanel, and comprehensive CI testing.

It's a system of record for the customer lifecycle of a Brazilian accounting SaaS (sales handoff, onboarding, contracts, contacts, portfolios, beneficiaries, bank accounts, digital certificates, meetings, operational status).

• Contributed to a 25+ Django app monorepo and single-spa React micro-frontend covering the full customer lifecycle.
• Designed and rolled out API v2 with OpenAPI schema–driven TypeScript codegen, migrating traffic off v1 and eliminating FE/BE drift bugs.
• Architected per-app layering and an EventBridge-based event publishing system so domain events propagate without coupling services.
• Set up Celery workers with Redis locally and AWS SQS in production, including a native dead-letter-queue pattern, and hardened BigDataCorp integration to respect a 30k-call/month quota with caching and graceful degradation.
• Migrated infrastructure to a new AWS CDK Python stack with GitHub Actions deploys to dev/staging/prod.
• Built and refactored major customer-detail UI sections, migrated server state to TanStack Query v5 with optimistic updates, standardized forms on react-hook-form + Zod, and drove gradual migration from MUI to Radix + Tailwind + shadcn.
• Wired Auth0, Datadog (APM + Browser RUM), Mixpanel, and Harness Feature Flags end-to-end; wrote pytest and Jest/RTL test suites.

It's an initiative to overhaul the e-invoicing and tax compliance stack for the Mexican marketplace in response to a major tax reform requiring fundamental changes to how invoices are issued, validated, and reported to the tax authority (SAT).

• Owned engineering delivery for the legacy Java invoicing service, leading technical strategy, scoping, and execution of all tax reform–required changes.
• Acted as Technical Program Manager for the broader initiative, coordinating dependencies and delivery across 7+ engineering teams in different internal organizations.
• Designed and led implementation of a new Java service with AWS CDK to collect inbound invoices from third-party sellers, including integration with Mexico's SAT for invoice validation.
• Drove alignment between conflicting stakeholder priorities on scope and timeline tradeoffs, renegotiating delivery commitments when upstream dependencies slipped.
• Reduced operational load by 20% (incidents) and 30% (service requests) through structured root-cause analysis, weekly operational reviews, and backlog grooming focused on recurring issues.
• Mentored and promoted software development engineers across levels, coaching on technical scoping, design reviews, and stakeholder communication.
• Partnered with non-technical teams (tax managers, external consultants, legal) to translate regulatory requirements into engineering specifications and acceptance criteria.

It's a high-scale e-invoicing platform that issues legally compliant electronic invoices for every customer purchase on the Indian marketplace, integrating directly with the Indian government's tax authority for invoice authorization.

• Designed and built the e-invoicing service from the ground up in Java and AWS CDK, integrating with India's GST Network for real-time invoice authorization.
• Led the design of resilience patterns for frequent government API downtime, reducing customer-facing impact from hours to minutes during outages.
• Designed the fixed-IP networking architecture required for government compliance using AWS Step Functions, Lambda, and ENIs.
• Drove SLA negotiations between conflicting stakeholder requirements (operations vs. retail) to align on the failure-handling approach, unblocking a stalled decision and preventing further shipment delays.
• Integrated the service with Amazon's global invoicing platform (GISv3), coordinating with two other engineering teams on shared design decisions.
• Designed and led implementation of the automated government API testing suite to validate integrations against the live tax authority sandbox.
• Owned the post-launch transition to the long-term ownership team, defining acceptance criteria and quality gates for the handover.