Open to new opportunities

Hi, I'm Carlos Monsalve

Senior Full Stack Engineer
AI / LLM Integration.

Senior Full Stack Engineer with nearly 20 years of experience in backend, architecture, APIs and end-to-end applications. Experience with TypeScript, Python, Node.js, NestJS, Next.js and React, together with practical LLM, RAG and generative AI integration.

View my work My experience ↓ Download CV

TypeScriptPrimary language

Next.jsWeb applications

NestJSScalable backend

ReactWeb interfaces

AILLM Integration

About me

Technical experience, product thinking and continuous evolution.

I build software by connecting business needs, maintainable architecture and end-to-end execution.

Senior Full Stack Engineer with nearly 20 years of software-development experience, specializing in backend, architecture, APIs and end-to-end applications.

I work mainly with TypeScript, Python, Node.js, NestJS, Next.js and React, building business platforms, REST APIs and integrations with cloud services and enterprise platforms.

I also have hands-on experience integrating LLMs, RAG and generative AI solutions, including conversational assistants, AI workflows and document processing.

In recent projects I have worked with Google Gemini, OpenAI, LangChain, LangGraph, vector databases, tool calling, MCP, provider abstraction, provider fallback, context control, Multi-Tenancy, RBAC, error handling and usage limits.

Career: Nearly 20 years
Location: Madrid, Spain
Specialization: Full Stack, architecture and business applications
Education: FP2 / Higher Degree in Computing · IUTA, Venezuela · 2007
Languages: Native Spanish · A2 English, continuously improving

Full Stack Development

Building modern web applications with TypeScript, React, Next.js, Node.js and NestJS.

Backend & APIs

Designing REST APIs, authentication, authorization, service integrations and data models.

Software Architecture

Applying DDD, Clean Architecture and design patterns pragmatically.

Business Applications

Evolving administration, promotion, loyalty, cashback, wallet, analytics and operational platforms.

Cloud & Integrations

Integrating AWS, Salesforce Data Cloud, Salesforce Service Cloud and external services.

LLM Integration

Integrating conversational assistants, AI workflows and document processing with controlled context and boundaries.

Continuous evolution

A foundation in enterprise software and data that evolved into the TypeScript ecosystem, cloud and SaaS products.

End-to-end perspective

I work from domain modeling and APIs through interfaces, persistence and external integrations.

Professional evolution

From enterprise applications to AI-assisted engineering.

Six stages summarizing how my approach to building software has evolved, without repeating company and responsibility details.

012005 — 2010
Enterprise and data foundations
Began professionally with internal applications, management modules, reporting and solutions connected to real business processes.
Visual BasicOracleSQL ServerPL/SQL
022010 — 2016
Web and business applications
Evolved toward corporate web applications, relational databases, digital campaigns and tools for operational teams.
PHPASPJavaScriptSQL
032021 — 2023
Full Stack Development
Consolidated an end-to-end profile through reusable frontend, backend services, REST APIs and data modeling.
JavaScriptPHPCodeIgniterREST APIsMySQL
042023 — 2024
Automation and integrations
Automated operations and integrated enterprise ITSM platforms, reporting systems and data-transformation workflows.
PythonPowerShellITSMSQL Server
052024 — 2026
SaaS and modern architectures
Built multi-tenant TypeScript platforms with maintainable architecture, security, cloud integrations and Salesforce.
Next.jsNestJSLaravelDDD
06Current focus
AI-assisted engineering
Uses assistants and LLMs responsibly to accelerate analysis and delivery without delegating validation or technical decisions.
GitHub CopilotGeminiLLMsEngineering judgment

Experience

Building software across the full stack.

My career spans enterprise applications, frontend, backend, APIs, databases, architecture, cloud, integrations and business platforms.

Apr 2024 — Jul 2026

Madrid, Spain

Full Stack Developer

Dinero Gelt S.L.

End-to-end design and development of production business platforms across frontend, backend, APIs, business logic and integrations.

Contributed to an LLM-assisted ticket-validation solution through the document preparation and normalization pipeline before OCR processing.
Processed and transformed documents and images: multi-page PDF to images, HEIC to JPG, and page composition for subsequent AWS Textract processing.
Backend services and REST APIs with TypeScript, NestJS and Laravel, applying DDD, Clean Architecture and design patterns.
Multi-tenant architectures with authentication, RBAC, data isolation and organization-level operation validation.
AWS S3, AWS SES, Salesforce Data Cloud, Salesforce Service Cloud and Postmark integrations.
Loyalty, cashback, wallets, promotions, analytics and administration features.

TypeScriptReactNext.jsNestJSLaravelREST APIsDDDClean ArchitectureMulti-TenancyRBACJWTOAuth2AWS S3AWS SESAWS TextractSalesforce Data CloudSalesforce Service CloudPostmarkLLM Integration

Dec 2023 — Mar 2024

N2 Applications Consultant

Ambit BST

Automation, ITSM integrations, data management and technical support.

ITSM automation and integrations with Python, PowerShell and JavaScript.
REST API integration for ServiceDesk Plus, EasyVista and Matrix42.
Data management and reporting.
Technical incident analysis and resolution.
Operational documentation.

PythonPowerShellJavaScriptREST APIsServiceDesk PlusEasyVistaMatrix42

Mar 2021 — Apr 2023

Full Stack Developer

Siniestrauto

Developed and evolved a real-time vehicle-auction platform across frontend and backend.

Development with JavaScript, PHP, Node.js, Laravel and CodeIgniter.
Real-time communication through Socket.IO.
Database design and maintenance.
Business logic and SQL query optimization.

JavaScriptPHPNode.jsLaravelCodeIgniterSocket.IOSQL

Mar 2015 — Jun 2016

Front-end Developer

Hallon Intelligence S.L.

Developed and maintained web applications, newsletters and corporate communication solutions.

PHP, ASP, HTML and SQL.
Maintenance of relational databases, procedures and internal web tools.

PHPASPHTMLSQL

Jun 2010 — Oct 2014

Software Developer

Materiales Pro-Alí 52, C.A.

Software development.

Visual Basic, Java, SQL Server and Crystal Reports.

Visual BasicJavaSQL ServerCrystal Reports

Apr 2008 — Jun 2010

Software Developer

IBM (Software Factory) – CANTV

Software development.

ASP, Oracle and PL/SQL.

ASPOraclePL/SQL

Apr 2007 — Oct 2007

Software Developer

Corporación Sybven

Software development.

Visual Basic and Oracle.

Visual BasicOracle

Apr 2006 — Feb 2007

Software Development

GTSupport C.A.

Software development.

Microsoft Access and SQL Server.

Microsoft AccessSQL Server

Jan 2005 — Oct 2005

Software Developer

Distribuidora PRO-Alí C.A.

Business-management software development.

Selected Projects

Building products that solve real problems.

Three projects that reflect my work in Full Stack platforms, document processing and practical LLM integration.

LLM Integration · Document ProcessingJun 2025 - Nov 2025

Dataco Express — AI-assisted ticket processing

Professional project related to my work at Dinero Gelt S.L.

Contributed to an LLM-assisted ticket-validation solution in a high-volume user and traffic environment.

The challenge

Prepare documents with varied formats and pages for subsequent processing.

My contribution

My contribution focused on the document preparation and normalization pipeline.

Multi-page PDF-to-image conversion.
HEIC-to-JPG transformation.
Vertical composition of pages and images.
Preparation for subsequent processing with AWS Textract.
OCR processing, LLM interpretation and semantic matching were mainly developed by other team members.

Architecture and patterns

Document PreparationNormalization Pipeline

Technology stack

LLM IntegrationDocument ProcessingPDFHEICAWS Textract

Full Stack · SaaS · LLM IntegrationJun 2026 - Jul 2026

Commerce Platform — Full Stack Multi-Tenant SaaS

Business platform with LLM-based operational assistance

A multi-tenant SaaS platform for products, customers, sales, purchasing and operations.

The challenge

Preserve organization-level isolation while providing operational assistance without direct model access to the database.

My contribution

Developed the architecture, backend and REST APIs, plus a read-only Operations Assistant with organization-controlled context.

Modular DDD and Clean Architecture with data isolation by organization.
Backend and REST APIs for products, customers, sales, purchases and operations.
LLM-based Operations Assistant integrated with NestJS and Next.js.
Google Gemini as the primary provider and OpenAI as fallback through a shared abstraction.
Assistive, read-only AI workflows with organization-controlled context and no direct model access to the database, Prisma or SQL.
JWT, RBAC, Multi-Tenancy, provider fallback, rate limits, Retry-After, retries and error handling.

Architecture and patterns

DDDClean ArchitectureMulti-TenancyProvider Abstraction

Technology stack

TypeScriptNestJSNext.jsReactPrismaPostgreSQLGoogle GeminiOpenAI APIJWTRBAC

View repository

Personal product · Full Stack · LLM IntegrationAug 2026

Personal Portfolio — Full Stack Developer

Professional portfolio with an LLM-based conversational assistant

An end-to-end portfolio built with Next.js and TypeScript that includes a Google Gemini conversational assistant.

The challenge

Keep professional information structured, secure and available to both the interface and assistant.

My contribution

Developed the application, content architecture and server-side conversational assistant.

End-to-end development with Next.js and TypeScript, integrating Google Gemini.
Conversational assistant through Google Gemini's generateContent REST API.
System prompts, dynamic contextualization and relevant-information selection from structured portfolio content.
Server-only API keys, response validation, retries and quota handling.

Architecture and patterns

Content-driven ArchitecturePrompt DesignServer-only Integration

Technology stack

Next.jsTypeScriptGoogle GeminiREST APIReactnext-intl

Certifications

Verified AI learning.

Professional certifications that complement my hands-on experience in software engineering and AI.

IBM · Coursera · October 2026

IBM RAG and Agentic AI Professional Certificate

Professional Certificate focused on Retrieval-Augmented Generation (RAG), Generative AI and agentic AI systems.

View Certificate Verify Credential

How I work

Principles applied to real problems.

Architecture, security, quality and AI used pragmatically to build reliable and maintainable software.

Domain-oriented architecture

I model software around the business and separate responsibilities so important rules remain independent of frameworks and persistence.

Domain-Driven DesignClean ArchitectureRepository PatternMapper PatternCriteria Pattern

Security and isolation

I design authentication, authorization and tenant boundaries as part of the architecture rather than treating them as late-stage fixes.

JWTOAuth2RBACMulti-Tenant Security

Quality and observability

I combine types, validation, tests, explicit errors and traceability to build systems that can evolve and operate reliably.

Type SafetyZodJestPlaywrightAudit LogsCorrelation IDs

LLM Integration

I integrate LLMs into applications with provider abstraction, controlled context, fallback and explicit handling of limits and errors.

Google GeminiOpenAI APIRAGAgentic AILangChainLangGraphVector DatabasesTool CallingMCPProvider AbstractionFallback StrategiesRate Limits & Error HandlingPrompt Engineering

Tech Stack

Technologies I work with.

Technologies, tools and engineering practices I use to build scalable, maintainable, business-oriented software.

LLM & AI Integration

Integrating LLM capabilities into software applications with controlled context and reliable provider handling.

LLM IntegrationRAGAgentic AIAI WorkflowsLangChainLangGraphVector DatabasesTool CallingMCPPrompt EngineeringGoogle GeminiOpenAI APIProvider Abstraction

Frontend

Building modern and interactive user experiences.

TypeScriptPythonReactNext.jsHTMLCSSTailwind CSSMaterial UI

Backend

Designing APIs and scalable backend services.

Node.jsNestJSLaravelREST APIs

Data

Working with relational databases and modern ORMs.

PostgreSQLMySQLPrismaSQL

Cloud & Integrations

Connecting applications with cloud platforms and external services.

AWSAWS S3AWS SESAWS TextractDocker

Engineering

Building maintainable and scalable software.

DDDClean ArchitectureRepository PatternMulti-TenancyOAuth2JWTRBACMapper PatternCriteria Pattern

Beyond code

The person behind the software.

My roots, family and dance are part of how I understand life, relationships and learning.

I am Venezuelan, and my roots are an essential part of who I am. My personal and professional journey between Venezuela and Spain has exposed me to different contexts and helped me build an open and adaptable perspective.

I am deeply family-oriented. My wife and son are central to my life, and I deeply value closeness, shared time and mutual support.

Alongside my technology career, I still teach Kizomba, Bachata and Salsa as a hobby. Dance is a personal passion and a space to enjoy, teach, connect with people and continue learning.

Dance

KizombaBachataSalsa

Venezuelan roots

My origin is part of my identity and shapes the perspective I bring to new experiences and change.

Family first

My wife and son are my greatest source of balance, motivation and perspective.

Communication

Explaining ideas clearly and adapting the message to people with different backgrounds.

Teaching

Sharing knowledge with patience, empathy and a structure that is easy to follow.

Discipline

Learning continuously, practicing consistently and improving through attention to detail.

Contact

Let's build something great together.

I'm open to new opportunities, interesting projects and conversations about technology.

Let's connect

Whether you're looking for a Senior Full Stack Engineer, want to discuss a project or simply connect, feel free to reach out.

Location

Madrid, España

Phone

+34 603 418 079

monsalvecarlos@gmail.com

Connect professionally

GitHub

Explore my code

Portfolio

carlosmonsalve.dev

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Senior Full Stack Engineer
AI / LLM Integration.

TypeScriptPrimary language

Next.jsWeb applications

NestJSScalable backend

ReactWeb interfaces

AILLM Integration

Senior Full Stack EngineerAI / LLM Integration.

Technical experience, product thinking and continuous evolution.

Full Stack Development

Backend & APIs

Software Architecture

Business Applications

Cloud & Integrations

LLM Integration

Continuous evolution

End-to-end perspective

From enterprise applications to AI-assisted engineering.

Enterprise and data foundations

Web and business applications

Full Stack Development

Automation and integrations

SaaS and modern architectures

AI-assisted engineering

Building software across the full stack.

Full Stack Developer

N2 Applications Consultant

Full Stack Developer

Front-end Developer

Software Developer

Software Developer

Software Developer

Software Development

Software Developer

Building products that solve real problems.

Dataco Express — AI-assisted ticket processing

The challenge

My contribution

Architecture and patterns

Technology stack

Commerce Platform — Full Stack Multi-Tenant SaaS

The challenge

My contribution

Architecture and patterns

Technology stack

Personal Portfolio — Full Stack Developer

The challenge

My contribution

Architecture and patterns

Technology stack

Verified AI learning.

IBM RAG and Agentic AI Professional Certificate

Principles applied to real problems.

Domain-oriented architecture

Security and isolation

Quality and observability

LLM Integration

Technologies I work with.

LLM & AI Integration

Frontend

Backend

Data

Cloud & Integrations

Engineering

The person behind the software.

Venezuelan roots

Family first

Communication

Teaching

Discipline

Let's build something great together.

Let's connect

Senior Full Stack EngineerAI / LLM Integration.

Technical experience, product thinking and continuous evolution.

Full Stack Development

Backend & APIs

Software Architecture

Business Applications

Cloud & Integrations

LLM Integration

Continuous evolution

End-to-end perspective

From enterprise applications to AI-assisted engineering.

Enterprise and data foundations

Web and business applications

Full Stack Development

Automation and integrations

Senior Full Stack Engineer
AI / LLM Integration.

Senior Full Stack Engineer
AI / LLM Integration.