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Leon – LLM, Python, AWS, experts in Lemon.io

Leon

From Brazil (UTC-3)flag

Back-end Web Developer|Senior
Machine Learning Engineer|Middle
AI Engineer|Middle
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Leon – LLM, Python, AWS

Leon is an engineer with a Data Science degree, currently working at the intersection of backend development and AI. He was assessed as a Senior professional in backend using Python. Leon has hands-on experience building production-grade APIs, LLM-based services, and NLP solutions, and operates at an intermediate level in AI/ML engineering. Leon demonstrates clear system design instincts, collaborative communication, and a proactive learning mindset, making him well-suited for startup environments.

6 years of commercial experience
Main technologies
LLM
1 year
Python
5.5 years
AWS
1.5 years
GCP
1.5 years
Additional skills
LangChain
FastAPI
Tensorflow
Flask
LangGraph
Scikit-learn
PyTorch
Direct hire
Possible
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Experience Highlights

Senior Full-Stack Developer
Sep 2025 - Ongoing4 months
Project Overview

A full-scale asynchronous platform developed to automate the classification and extraction of critical corporate documents. Unlike standard keyword-matching tools, this system uses AI to evaluate the purpose and function of documents, effectively handling regional terminology, abbreviations, and synonyms across Brazil, Mexico, and international markets. It serves as a central hub for compliance, replacing manual, labor-intensive verification processes that previously drained valuable work hours.

Project gallery:
Portfolio example for DocAI - Document Intelligence classifier and extractor by Leon Balloni, Senior Full-Stack Developer
Responsibilities:
  • Architected a performant async platform capable of classifying documents based on core function rather than simple text patterns.
  • Developed a rendered frontend for simplified and direct product team usage of the solution.
  • Implemented regional classification logic for 6 specific document types, including Brazilian, Mexican, and some global documents.
  • Designed the multi-agent AI system that interprets complex legal terminology to ensure accurate categorization across diverse LATAM jurisdictions.
  • Reduced manual curation costs and improved evaluation speed for massive document volumes, directly impacting SLA reliability.
  • Deployed automated CI/CD pipelines using GitHub Actions, ensuring safer tagging and versioning for high-frequency updates.
Project Tech stack:
Python
Mistral LLM
OpenAI API
FastAPI
LangChain
AI agent development
SQLAlchemy
JavaScript
HTML
CSS
Senior Full-Stack Developer
Mar 2025 - Ongoing10 months
Project Overview

A service curating both public and private sources for risk and false positive entity-related information. The application addresses companies and people from all around LATAM and international countries to check sources, classifying their compliance risk and generating a scoring that determines if the entity is indeed related to the entity identified in the article, thus speeding the evaluation of massive volume of articles for thousands of customers, reducing the cost of curating, checking and classifying those content manually and easing up the access of multiple combined of sources.

Project gallery:
Portfolio example for Compliance Risk and Entity False Positive classifier by Leon Balloni, Senior Full-Stack Developer
Portfolio example for Compliance Risk and Entity False Positive classifier by Leon Balloni, Senior Full-Stack Developer
Responsibilities:
  • Designed the back-end, front-end section, and the AI systems used in the current product;
  • Created the integration of multiple data sources by adding a common interface that supports multiple article sources;
  • Worked on a new Scraper to extract public articles (extracting more than 10k articles daily);
  • Created a database that holds more than 100k entity-articles evaluated by the AI system;
  • Deployed solution using CI/CD in git actions and an automated versioning system for safer tagging;
  • Impacted over 4 reports and 1 new API pipeline under testing for data|AI as a service. (LATAM and International)
Project Tech stack:
Python
LangChain
pytest
FastAPI
OpenAI API
AI agent development
AI
JavaScript
HTML
CSS
Back-End Developer
Apr 2024 - Jul 20251 year 3 months
Project Overview

A specialized data analytics and profiling platform created to identify the distinguishing factors between high-performance and low-performance student categories. The platform extracts raw educational data, profiles student behavior, and applies unsupervised learning to discover hidden clusters within the student body. This enabled the company to move beyond surface-level metrics and understand the underlying drivers of academic success within its institution.

Project gallery:
Portfolio example for Sagres Analyzer - Student Performance Analytics by Leon Balloni, BackEnd Developer
Responsibilities:
  • Created a sliced student profiling system that categorized students into 9 quadrants (from lowest to highest performance) based on class presence and activity execution.
  • Developed an unsupervised model using K-Means clustering to extract distinct clusters of student behaviors automatically.
  • Built interactive visualization tools with Streamlit, providing stakeholders with clear exploratory and explanatory data reports.
  • Deployed the solution in a secure VM environment, providing a friendly and restricted interface for authorized Sagres users.
Project Tech stack:
Python
Pandas
Flask
Algorithms and Data Structures
Scikit-learn
Data Science
Data Scientist
Feb 2022 - Feb 20231 year
Project Overview

An intelligent NLP solution designed to process real-time financial news streams using natural language processing (NLP). The system focuses on named entity recognition (NER) and multi-label classification to tag and categorize market-moving information automatically. By leveraging TC’s private datasets, the platform surfaces relevant news with minimal latency, providing a significant competitive advantage in financial data analysis and enabling our clients to customize news retrieval.

Project gallery:
Portfolio example for Finance News Multi-Labelling (TradersClub) by Leon Balloni, Data Scientist
Portfolio example for Finance News Multi-Labelling (TradersClub) by Leon Balloni, Data Scientist
Responsibilities:
  • Developed an NLP architecture for multi-categorization and multi-labeling of high-frequency financial news.
  • Built and optimized a multi-label classification system to provide intelligent data-driven insights to users.
  • Curated training datasets using Argilla, leveraging private data to improve the accuracy of financial entity recognition.
  • Collaborated with the ML team to build end-to-end intelligent solutions that transformed raw text into actionable financial intelligence.
Project Tech stack:
NumPy
Python
Spacy
FastAPI

Education

2020
Chemical Engineering
Bachelor's
2026
Data Science and Information Technology
Bachelor's

Languages

English
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