Ennio Alejandro Gonzalez Castillo
Verified Expert in Engineering
Back-end Developer
Valencia, Carabobo, Venezuela
Toptal member since August 4, 2021
Ennio is a back-end developer with over seven years of experience. He has worked with several technologies in his career, showing a complete set of skills while learning new languages/frameworks. His current stack of technologies is Node.js, NestJS, relational databases, Redis, and GraphQL. In his career, Ennio has gained experience in several industries, such as accounting, airport, blockchain, eCommerce, social networks, database, file management software, and healthcare.
Portfolio
Experience
- SQL - 5 years
- Databases - 5 years
- PostgreSQL - 5 years
- REST APIs - 4 years
- TypeScript - 3 years
- NestJS - 3 years
- JavaScript - 3 years
- PHP - 2 years
Preferred Environment
Slack, Jira, Confluence, MacOS, GitHub
The most amazing...
...project I've done so far was creating an eCommerce system from scratch—the system has not yet gone into production.
Work Experience
Back-end, Node.js, and NestJS Developer
Capital Hill Management, Inc.
- Developed four production-ready RESTful APIs—support plan, support plan subscriptions, cluster subscriptions, and subscription auth—using NestJS and MongoDB, fully aligned with client requirements and documented via Swagger for seamless integration.
- Implemented secure API authentication logic and integrated it into Swagger UI, enabling authenticated testing and significantly improving development and QA workflows.
- Built and deployed three automated cron jobs responsible for processing recurring subscription payments, ensuring reliable billing cycles, and reducing manual intervention by 100%.
Back-end Developer
Kenility LLC
- Developed an integration with Google Business Profile to let users receive information about the apartments, houses, and units available via their chat on the business profile.
- Built an integration with Facebook Messenger to let users ask and receive information about the units available via Facebook Messenger.
- Analyzed and fixed bugs related to the real estate platform.
- Created a chatbot from scratch using a large language model (LLM) and custom-designed prompts to handle diverse customer interaction scenarios.
TypeScript Back-end Engineer
Terminal Technologies Inc.
- Developed several API integrations, enabling Terminal’s platform to aggregate fleet data, including mileage, fuel consumption, and driver activity, for seamless client access with diverse telematics providers.
- Built integrations for multiple telematics APIs to retrieve real-time location data for fleet trucks, enabling centralized and accurate client tracking across diverse telematics systems.
- Streamlined documentation across multiple API integrations, improving clarity and consistency in both English and Spanish.
Team Lead
PynPon LLC
- Developed functional platform requirements guided by client data so that all the system specifications were agreed upon beforehand.
- Created the system architecture and selected the tech stack.
- Built the system database that met the client's needs, thanks to the functional requirements collected.
- Managed and assigned tasks to be done in the sprints for the back-end team.
- Deployed back-end and front-end projects on the servers every time new changes were uploaded.
- Managed the team regarding the implementation of Scrum in all the sprints carried out, which usually lasted two weeks each.
- Constructed the back-end architecture so the back end could communicate in real time with a mobile delivery app.
- Implemented a cache system to obtain products faster with Redis.
TypeScript Back-end Developer
Stop Talking LLC
- Developed the integration with Stripe to fully satisfy the client's billing process needs.
- Designed and implemented the permissions system of the platform.
- Developed the integration with YouTube API to retrieve the users' channels and YouTube videos.
Node.js Developer
Astrodon Corporation
- Developed an integration of Next.js with a Stripe API.
- Tracked customers' subscriptions with the possibility of canceling them at any point.
- Integrated the Stripe checkout and customer portal.
Back-end Developer
LeanXcale S.L.
- Developed a TypeORM driver/connector to be able to use TypeORM with the LeanXcale database engine.
- Tracked and reported bugs in the LeanXcale database engine.
- Debugged and fixed failing tests that TypeORM provides for every driver that it supports.
Back-end Developer
Facerent Technologies Inc.
- Developed the integration between the back end and smart contracts to be able to mint NFTs.
- Created multiple end-to-end tests of the developed features.
- Generated a telegram bot that is used for moderation purposes.
- Built all the logic for in-app messaging, where users could send messages and share content.
- Added watermarks to all photos and videos uploaded to the platform.
- Generated thumbnails for every photo uploaded to the system.
- Developed the integration between the Stripe platform so that users could add coins to their wallets.
Developer
Ocho La Super App
- Researched the system's database to optimize and migrate it from MySQL to PostgreSQL.
- Gathered information to add new requirements to the implemented database.
- Created an API in NestJS to consume information from the new database.
Database Administrator
SkyFlot, C.A
- Managed the databases in all the different company systems.
- Optimized database queries which reduced the response times of the application.
- Synchronized the billing of 14 airports nationwide to make invoice reconciliation easier; this was a project that I worked on from scratch.
Database Associate Professor
University of Carabobo
- Helped students in the practices related to the database class.
- Imparted knowledge associated with the creation of efficient database queries.
- Developed practical PostgreSQL workshops with the aim of evaluating students' knowledge in query creation.
Developer
Intelix Synergy, C.A
- Documented synchronization processes (stored in databases) between the company and the banking service provider. Previously it had stopped working and no one knew the reason.
- Fixed bugs discovered during the synchronization of bank movements.
- Optimized queries to databases; this area was an application bottleneck and was slowing down development.
Developer
Cardisoft F.P.
- Developed the modules for a telemedicine platform where patients and doctors communicated through video calls.
- Added new functionalities to an administrative system built with ASP.
- Created a user notification platform with a mass mailing feature.
Software Developer
Factory Soft
- Developed more than 1,500 accounting, payroll, and human resources reports.
- Optimized database queries to reduce response times.
- Generated OLAP cubes that consumed information from a database.
- Developed database triggers and functions to replicate products in real-time from a database. This was done for two database copies.
Experience
LeanXcale TypeORM Driver
https://gitlab.com/leanxcale_public/typeorm/-/tree/leanXcaleNFT Social Media
PynPon eCommerce
https://www.pynpon.com/Invoice Synchronization
Telemedicine Platform
Education
Bachelor's Degree in Computer Science
University of Carabobo - Valencia, Carabobo, Venezuela
Certifications
EF SET English Certificate 64/100 (C1 Advanced)
EF Standard English Test (EF SET)
JavaScript (Basic)
HackerRank
SQL (Basic)
HackerRank
SQL (Intermediate)
HackerRank
Skills
Libraries/APIs
REST APIs, Node.js, Passport.js, Sockets, jQuery, ASPX, Redis Queue, Sharp, FFmpeg, Stripe, ODBC, Stripe Connect API, Stripe API, Stripe Connect, Google My Business API, Facebook API, Facebook Messenger API, YouTube API, React, Auth, OpenAI API, Vonage SMS API, Vonage Voice API, Vonage Messages API, Twilio API, Back-end APIs, Socket.IO, Bitbucket API, Google APIs, Google Maps, Google Maps API, API Development, Facebook SDK, Social Media APIs
Tools
Git, Slack, Bitbucket, Jira, Confluence, Google Compute Engine (GCE), GitLab, Crystal Reports, NGINX, PM2, Auth0, Cron, Subversion (SVN), Apache, GitHub, Mocha, Visual Studio, Stripe Checkout, Prisma, Amazon Simple Queue Service (SQS), Amazon Simple Notification Service (SNS), Asana, Sentry, AWS Step Functions, Microsoft Teams, AI Prompts, Watchdog, SendGrid, Postman, AWS Command Line Interface (CLI), Amazon CloudWatch, ChatGPT
Languages
SQL, TypeScript, Transact-SQL (T-SQL), JavaScript, PHP, ECMAScript (ES6), C++, C, Java SE (Core Java), Assembler, Prolog, Haskell, Java, Active Server Pages (ASP), HTML, CSS, GraphQL
Frameworks
NestJS, CodeIgniter, CodeIgniter 3, .NET, Jest, Next.js, Express.js, Swagger, Fastify
Paradigms
Database Design, Scrum, Business Intelligence (BI), OLAP, Testing, REST, RESTful Development, Microservices, E2E Testing, Unit Testing
Storage
Databases, PostgreSQL, MySQL, Database Architecture, SQL Triggers, SQL Functions, Google Cloud Storage, Google Cloud, Redis Cache, Redis, LeanXcale, MongoDB, Amazon DynamoDB, SQL Server 2007, Microsoft SQL Server, Datadog, API Databases, Database Testing
Platforms
Windows, Linux, Google Cloud Platform (GCP), Docker, Amazon Web Services (AWS), YouTube, Vercel, AWS Lambda, Heroku, MacOS, Twilio, Firebase
Industry Expertise
Social Media
Other
Software, Algorithms, TypeORM, English, Leadership, Scrum Master, Software Architecture, Documentation, University Teaching, Servers, Networks, Bots, Polygon, Non-fungible Tokens (NFT), Apollo Server, Ethers.js, Team Management, Code Review, Source Code Review, Interviews, Interviewing, Technical Hiring, Task Management, Task Analysis, API Integration, Stripe Payments, Stripe Subscriptions, Stripe Managed Accounts, Payment APIs, Card Payments, Online Payments, APIs, Integration, RESTful Services, Webhooks, YouTube Marketing, YouTube Ads, Google BigQuery, Back-end Development, GitHub Actions, Reverse Engineering, Back-end, Cloud Platforms, Cursor AI, Subscriptions, ChatGPT Prompts, Large Language Models (LLMs), OpenAI, OpenAI GPT-3 API, OpenAI GPT-4 API, AI Tools, Vonage, Cloud, RESTFul APIs, WebSockets, Vercel Analytics, Libraries, eCommerce, eCommerce APIs, Third-party APIs, Artificial Intelligence (AI), ChatGPT API, Apollo, Customer Relationship Management (CRM), API Design, API Gateways, Facebook, Social Media Platforms, Social Media Login, AI Chatbots, Chatbots
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