Juan Céspedes
Systems engineer · full-stack · data · automation
I design, build and run software in production: web applications, data and automations used today by the operations, procurement and finance teams of a power generation company.
Barranquilla, Colombia · remote
By the numbers
Results you can verify
6
web systems in production for operations, procurement and financeSource: Internal repository audit, September 2026 1,400+
automated tests in the operations logbookSource: Operations logbook test suites (node:test and Vitest), September 2026 2 s
polling interval for 5 energy meters over Modbus TCPSource: Telemetry service configuration and latency measurements (p50 15 to 25 ms) 134
bilingual pages meeting WCAG 2.2 AA on the corporate websiteSource: Corporate website release, 2026 2,236
commits to the corporate website monorepo in 6 monthsSource: Corporate website repository history, April to September 2026
Projects
Systems in production and open source
Real cases. Internal systems are closed source, so each case explains the problem, the decisions and the results.
7 projects
2026 to present
I replaced the Excel shift logbooks with a real-time web application, with shifts as a business entity, official reports generated from the data and more than 1,400 automated tests.
- React
- Vite
- Node.js
- Express
- WebSockets
- SQL Server
- Microsoft Entra ID
- Microsoft Graph
- Excel
- Linux
- nginx
- systemd
1,400+automated test cases across backend and frontend
2026 to present
I built the service that reads five energy meters every 2 seconds, integrates energy per hourly period, compares it against the market dispatch and feeds a live dashboard and a Power BI report.
- Node.js
- Python
- Modbus TCP
- WebSockets
- SQL Server
- Microsoft Fabric
- PostgreSQL
- Power BI
- Microsoft Graph
- React
- Linux
- systemd
2 sread interval across 5 meters over Modbus TCP, with 15 to 25 ms p50 latency
2026
I rebuilt a power generation company's website from scratch, with 134 pages in Spanish and English on custom WordPress, deployments with automatic rollback and an external penetration test that closed with 3 low-severity findings.
- WordPress
- PHP
- Python
- Bash
- MariaDB
- Directus
- WCAG 2.2
- Playwright
- nginx
- Linux
134published pages, 67 in Spanish and 67 in English generated from a single source
2026 to present
I inherited a pipeline that lost invoices while reporting success. I audited it against production and put it under tests, CI and tag-based deployment; today it fails loudly, alerts on its own and can be audited invoice by invoice.
- Python
- Apache Airflow
- Selenium
- Oracle
- MongoDB
- Docker
- pytest
- GitHub Actions
- Model Context Protocol
- Legacy code rescue
- Incident forensics
74audit findings, each one backed by evidence measured against production
2026
I designed, built and single-handedly ran the platform for an energy-sector forum, with the agenda, a digital badge with a QR code, surveys, 156 audited PDF certificates and event memories, all behind corporate sign-in.
- React
- TypeScript
- Vite
- Node.js
- Express
- Microsoft Entra ID
- Microsoft Graph
- SQLite
- Python
- Playwright
- nginx
- systemd
163guests received their personal QR code by email, each one verified before sending
2026
A Python desktop application that turns PDF energy invoices from two companies with different formats into structured data, exports them to Excel and cross-checks them against the corporate database.
- Python
- pdfminer.six
- pandas
- PostgreSQL
- Excel
- CustomTkinter
- PyInstaller
73real invoices pinned as a regression corpus, with 26 fields checked in each one
2026 to present
A TypeScript MCP server and CLI that lets an AI assistant update a profile, engage with people and apply to jobs using the user's real session, with explicit confirmation before every action other people can see.
- TypeScript
- Node.js
- Model Context Protocol
- Playwright
- REST APIs
35+documented MCP tools for profile, engagement and job applications
No published projects with that capability yet.
Capabilities
Every skill, with the project that proves it
No percentages or bars: each technology links to the work where I used it.
Frontend
- ReactProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry, A corporate forum platform, from registration to certificate
- TypeScriptProven in A corporate forum platform, from registration to certificate, linkedin-pilot, an MCP server for LinkedIn
- ViteProven in Digital operations logbook for two thermal power plants, A corporate forum platform, from registration to certificate
- CustomTkinterProven in PDF energy invoice extractor for two formats
- WCAG 2.2Proven in Bilingual corporate portal with measured security and accessibility
- WordPressProven in Bilingual corporate portal with measured security and accessibility
Backend
- PythonProven in Real-time power generation telemetry, Bilingual corporate portal with measured security and accessibility, Rescuing an e-invoicing ETL that failed silently, A corporate forum platform, from registration to certificate, PDF energy invoice extractor for two formats
- Node.jsProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry, A corporate forum platform, from registration to certificate, linkedin-pilot, an MCP server for LinkedIn
- ExpressProven in Digital operations logbook for two thermal power plants, A corporate forum platform, from registration to certificate
- Microsoft Entra IDProven in Digital operations logbook for two thermal power plants, A corporate forum platform, from registration to certificate
- WebSocketsProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry
- DirectusProven in Bilingual corporate portal with measured security and accessibility
- PHPProven in Bilingual corporate portal with measured security and accessibility
- pytestProven in Rescuing an e-invoicing ETL that failed silently
- REST APIsProven in linkedin-pilot, an MCP server for LinkedIn
Data and BI
- ExcelProven in Digital operations logbook for two thermal power plants, PDF energy invoice extractor for two formats
- PostgreSQLProven in Real-time power generation telemetry, PDF energy invoice extractor for two formats
- SQL ServerProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry
- MariaDBProven in Bilingual corporate portal with measured security and accessibility
- Microsoft FabricProven in Real-time power generation telemetry
- Modbus TCPProven in Real-time power generation telemetry
- MongoDBProven in Rescuing an e-invoicing ETL that failed silently
- OracleProven in Rescuing an e-invoicing ETL that failed silently
- pandasProven in PDF energy invoice extractor for two formats
- pdfminer.sixProven in PDF energy invoice extractor for two formats
- Power BIProven in Real-time power generation telemetry
- SQLiteProven in A corporate forum platform, from registration to certificate
Automation and AI
- Microsoft GraphProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry, A corporate forum platform, from registration to certificate
- PlaywrightProven in Bilingual corporate portal with measured security and accessibility, A corporate forum platform, from registration to certificate, linkedin-pilot, an MCP server for LinkedIn
- Model Context ProtocolProven in Rescuing an e-invoicing ETL that failed silently, linkedin-pilot, an MCP server for LinkedIn
- Apache AirflowProven in Rescuing an e-invoicing ETL that failed silently
- SeleniumProven in Rescuing an e-invoicing ETL that failed silently
Infrastructure
- LinuxProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry, Bilingual corporate portal with measured security and accessibility
- nginxProven in Digital operations logbook for two thermal power plants, Bilingual corporate portal with measured security and accessibility, A corporate forum platform, from registration to certificate
- systemdProven in Digital operations logbook for two thermal power plants, Real-time power generation telemetry, A corporate forum platform, from registration to certificate
- BashProven in Bilingual corporate portal with measured security and accessibility
- DockerProven in Rescuing an e-invoicing ETL that failed silently
- GitHub ActionsProven in Rescuing an e-invoicing ETL that failed silently
- PyInstallerProven in PDF energy invoice extractor for two formats
Legacy systems
- Incident forensicsProven in Rescuing an e-invoicing ETL that failed silently
- Legacy code rescueProven in Rescuing an e-invoicing ETL that failed silently
Background
Experience and education
Experience
Jul 2024 to present
Information Technology Contractor
Gecelca S.A. E.S.P. · Barranquilla, Colombia
Development, operation and security of a power generation company's information systems, plus integration and analysis of its operational and financial data.
- Put 6 web systems of my own into production, used by operations, procurement, communications and finance.
- Rebuilt the bilingual corporate website (134 pages) to WCAG 2.2 AA, with automatic-rollback deployments.
- Built the digital operations logbook for two thermal power plants and real-time generation telemetry.
- Rescued a legacy e-invoicing ETL pipeline without stopping operations.
- My work passed an external penetration test with only 3 low-severity findings.
Education
Jan 2020 to Nov 2024
Systems Engineering
Universidad del Norte
Services
Let's work together
Fixed-price projects per deliverable, for companies and teams that need results in production.
Custom web applications
Portals, internal platforms and systems with corporate sign-in, from the database to deployment.
You get
- Application in production with automated tests
- Source code and architecture documentation
- Reproducible deployment and an operations guide
Data, dashboards and reports
Data models, ETL and Power BI dashboards that answer concrete business questions.
You get
- Documented data model and SQL queries
- Dashboard or report with agreed indicators
- Automatic refresh process
Automation and AI integration
Bots, document data extraction, integrations between systems and MCP servers for AI assistants.
You get
- Automation running on your systems
- Execution log and error handling
- User and maintenance guide
Legacy system rescue
Diagnosis, tests and modernization of software nobody dares to touch, without stopping operations.
You get
- Diagnosis report with prioritized risks
- Test suite that protects what already works
- Improvements delivered in stages
How we work
- 01ConversationYou tell me the problem and the result you need. I reply within one business day.
- 02ProposalScope, deliverables, timeline and a fixed price per deliverable, in writing.
- 03Staged deliveryProgress you can see and test, with a demo at every stage.
- 04Handover and supportCode, documentation and support so the system keeps running.
Quoted from your requirements, with a fixed price per deliverable.
Tell me about your projectCredentials
Education and certifications
Professional engineering license
COPNIA (Colombia)
May 2025Advanced Power BI and Excel Business Intelligence
LinkedIn Learning
Nov 2024Python for data analysis
Desafío Latam
Sep 2024Junior Cybersecurity Analyst
Cisco Networking Academy
Apr 2024English C2 (EF SET 81/100)
EF SET
Apr 2024Verify(opens in a new tab)Microsoft Certified: Azure Data Fundamentals
Microsoft
Nov 2022Microsoft Certified: Azure Fundamentals
Microsoft
Nov 2022
Contact
Tell me what you need
Use the form or write to me directly. I reply within one business day.