I build production systems under real-world constraints: limited budgets, legacy government infrastructure, data privacy compliance (LGPD), and zero margin for downtime.
I solo-developed and shipped visabelem.net, the digital sanitary surveillance platform for the city of Belém, serving a population of 1.3 million. Operating on a VPS and a highly-tuned SQLite database costing ~$500/year, the platform facilitated over $1M in municipal fee compliance by validating payments against the municipal tax system (SIAT) in its first 5 months of operation.
The repositories in this workspace are extracted architectural patterns, production libraries, and ETL pipelines derived from the challenges I faced while building and scaling this infrastructure.
Below is a catalog of the modules, patterns, and case studies included in this repository:
| Category | Project / Subfolder | Core Tech | Key Habilities & Patterns Demonstrated |
|---|---|---|---|
| Case Study | visabelem-architecture-case-study | System Design |
Modular monolith architecture, SQLite WAL optimization, polymorphism, phased database migration strategy. |
| Go Engineering | cnae-risk-classifier | Go |
High-performance concurrent classification, bounded goroutine fan-out, GC pressure reduction using sync.Pool. |
| Go Engineering | go-event-adapter-pattern | Go |
Event-driven webhook adapter, payload normalization, exponential backoff, Dead Letter Queue (DLQ). |
| Go Engineering | go-redis-cache-patterns | Go Redis |
Type-safe Cache-Aside implementation using Go Generics, atomic distributed locks via Lua scripts. |
| Go Engineering | go-n8n-webhook-validator | Go |
Security middleware, HMAC-SHA256 signature verification, timing-attack mitigation (ConstantTimeCompare). |
| Go Engineering | go-cnpj-prospector | Go |
Multi-API fallback proxy, numeric & alphanumeric CNPJ validation (COCAD 01/2024), thread-safe memory cache. |
| Go Engineering | go-sqlite-backup-daemon | Go SQLite |
Disaster Recovery WAL-shipping replication daemon, file polling, gzip compression, S3 HTTP uploading. |
| Go Engineering | go-pdf-signer | Go |
Cryptographic PDF PAdES signer & verifier service, PKCS#12 decoding, ByteRange hashing, RSA PKCS1v15 signatures. |
| Go Engineering | go-audit-trail-middleware | Go |
Cryptographic audit trail middleware (HMAC-SHA256), tamper-evident append-only JSON logging for LGPD. |
| Go Engineering | go-cptec-proxy | Go |
CPTEC XML weather & wave proxy, BrasilAPI JSON schema normalization & fallback, local memory cache, ISO-8859-1 translation. |
| Open Data Spec | cptec-data-catalogs | Markdown |
Comprehensive simplified mappings and technical dictionary for CPTEC/INPE FTP and DataServer repositories. |
| Backend Engineering | python-siat-cache-proxy | Python FastAPI SQLite |
Sidecar caching proxy, Cache-Aside pattern (infinite paid cache vs 15-min TTL), SQLite WAL optimization, LGPD log privacy by design. |
| Data Engineering | receita-federal-cnpj-miner | Python SQLite |
Streaming parsing of large-scale CSVs, spelling normalizations, checkpoint/resume mechanics, MEI detection. |
| Data Engineering | belem-transparency-analytics | Python pdfplumber |
Automated extraction and consolidation of municipal financial data (Lei 4320/64) from official Transparency Portals. Dynamically downloads PDFs, extracts complex nested tabular reports (Anexo 8, 9, 10, and Balancetes), and compiles cross-year comparative charts. |
| Data Engineering | node-etl-migration-scripts | Node.js |
Batch ETL pipeline for PocketBase, resumable database synchronization using mapping states. |
| Data Engineering | belem-geospatial-risk-mapping | Python Leaflet Shapely |
GeoPDF/PDF coordinate extraction pipeline, UTM grid linear regression (polyfit), CPRM/Defesa Civil risk data miner and Leaflet viewer. |
| GIS & Frontend | belem-geospatial-viz | React Leaflet ECharts |
Overpass API polygon repair (Shapely), canvas markers, interactive choropleth map. |
| GIS & Frontend | react-health-dashboard-poc | React TS |
High-performance dashboard widgets, SOLID component design, real-time indicator simulations. |
| GIS & Frontend | visabelem-mock | React TS Tailwind |
High-fidelity interactive prototype for stakeholder alignment, dual citizen/admin portal flows, and animated transitions. |
| Public Health & GIS | cisc-situation-room | HTML JS Tailwind |
Interactive Situation Room dashboard (Videowall) mapping multi-sector alerts (epidemiological, meteorological, water levels) and dispatching community educational bulletins. |
| Data Engineering | cisc-data-pipelines | Python SQLite SQL |
Health and climate ETL pipelines (SINAN, INMET, CEMADEN, Navy tides), statistical anomaly models (CUSUM, Spearman lag, logistic regression), and SQL database schemas (LGPD compliant - raw data omitted). |
| Go Engineering | go-cisc-telemetry-hub | Go gRPC GraphQL |
Central data ingestion and real-time distribution engine for the CISC Belém health-climate platform. Implements concurrent servers for gRPC and GraphQL Subscriptions (SSE). |
| Security & Data | ghdb-map-generator | Python HTML JS |
ETL pipeline processing large XML datasets (5.5MB) from ZIP files to generate an interactive tactical dashboard, demonstrating practical OSINT and vulnerability testing proficiency as a hobby. |
Open Source Scope: The repositories in this workspace are independently authored demonstrations and extracted architectural patterns. The production government system is closed-source under municipal contract. No proprietary government data, classified municipal assets, or production source code have been published.
- LinkedIn: linkedin.com/in/daniel-de-jesus
- Email: dpo@visabelem.net
This project is licensed under the MIT License - see the LICENSE file for details.