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Klein – Python, OpenAI, LLM, experts in Lemon.io

Klein

From Spain (UTC+4)

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AI EngineerSenior
5 years of commercial experience
AI
Computer science
Fintech
Human resources
AI software
Chatbots
NLP software
SaaS
Lemon.io stats
1
projects done
0
hours worked

Klein – Python, OpenAI, LLM

Klein is a seasoned AI Engineer with a physics background who transitioned from Machine Learning to AI, specializing in LLM orchestration over the past 2–3 years. As an early contributor to LangChain, he has expertise in RAG pipelines, prompt engineering, embeddings, and agent design.

Klein takes a deep dive into every challenge and takes a holistic approach with a strong focus on safety, observability, and agent guardrails. He excels in fast-paced startup cultures, enjoys contributing to both product and execution, and has experience working with C-levels and scaling a team.

Main technologies
Python
5 years
OpenAI
3 years
LLM
2.5 years
LangChain
2.5 years
AI
5 years
Additional skills
AWS
PyTorch
MLOps
RAG
Figma
Tensorflow
Visual Studio Code
UI/UX
GPT
Data analysis
Agile
BERT
Machine learning
Deep Learning
Amazon S3
DeepSeek
Chat bots
CI/CD
Hugging Face
Vector Databases
JSON Schema
ML
Data Science
Ready to start
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Potentially possible
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Experience Highlights

Full-stack AI Engineer
Dec 2024 - Ongoing4 months
Project Overview

It's a specialized speech-to-text SaaS offering fast, accurate transcriptions via custom ASR models for students and researchers.

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Responsibilities:
  • Created a full-stack SaaS audio transcription platform using Wasp (Node.js/Prisma) and a dynamic front end using React;
  • Integrated third-party services—Google Analytics, Auth0, and Stripe—for user insights, secure authentication, and payment management;
  • Created a real-time highlighting system syncing audio with transcript text for smoother editing and interactivity;
  • Oversaw the product design process, establishing information architecture, visual design (UI/UX), and user journeys to produce a user-friendly interface;
  • Implemented Whisper-small ASR on AWS SageMaker for a fast, cost-effective transcription option in the free tier;
  • Carried out data engineering procedures, such as cleaning, transforming, and preparing for AI model training and application use, on proprietary datasets;
  • Created an automated post-processing pipeline to improve the grammar, punctuation, and intelligibility of ASR transcripts by utilizing OpenAI's GPT-4o API.
Project Tech stack:
React
Next.js
OpenAI API
LangChain
Stripe API
Auth0
Google Analytics
Amazon S3
AWS Lambda
Amazon EC2
Docker
Hugging Face
OpenAI
Project management
RAG
Figma
Visual Studio Code
JSON Schema
GitHub
Prompt engineering
Supabase
Agile
Git
AI Engineer
Aug 2024 - Feb 20256 months
Project Overview

It's a tool that delivers real-time, context-specific behavioral coaching in Outlook, Teams, Gmail, and Slack to scale company culture.

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Responsibilities:
  • Optimized AI pipelines for HR coaching, cutting latency by 62% via prompt tuning, step reduction, and smart caching;
  • Reduced infrastructure costs by 30% and boosted accuracy by 20% via efficient token use, strategic caching, and varied AI tools for HR coaching;
  • Designed evaluation pipelines and synthetic data workflows to speed up QA and delivery for HR coaching used by 10k+ users per client.
Project Tech stack:
Prompt engineering
LLM
Claude LLM
OpenAI
CrewAI
AI
Data analysis
Data visualization
LangChain
Python
GitHub
OpenAI API
MLOps
RAG
Docker
GPT
Agile
Microsoft Azure
Cloud Computing
Git
DeepSeek
Lead AI Engineer
Feb 2023 - May 20241 year 3 months
Project Overview

It's a tool that provides professional-grade AI technology for equity research to the investment banking, hedge fund, asset management, and wealth management industries.

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Responsibilities:
  • Designed and implemented an advanced AI pipeline for financial document processing, integrating multi-agent systems, RAG architectures, and prompt engineering techniques, directly contributing to a $5M pre-seed valuation;
  • Deployed full-stack AI infrastructure on AWS, scaling from R&D to production-ready MVP;
  • Served as Interim CTO for 10 months, scaling the engineering team from 2 to 7 members;
  • Developed comprehensive evaluation frameworks with custom benchmarks to measure the performance of agents, prompts, and RAG systems;
  • Established quality assurance processes and documentation standards for maintaining technical advantages through research-backed approaches;
  • Successfully presented to VCs and prospects, helping secure initial funding and establish early customer relationships;
  • Transformed the product into a fully operational GenAI-based financial analysis tool with faster insights, reliable data aggregation, and an intuitive UX.
Project Tech stack:
LangChain
AI
AWS Lambda
Amazon S3
Cloud Computing
Computer Vision
Machine learning
Prompt engineering
Product management
Project management
Vector Databases
RAG
SQL
PyTorch
MLOps
Figma
Data visualization
Visual Studio Code
UI
UX
Agile
BERT
Deep Learning
CI
CD
CrewAI
Amazon EC2
GitHub
Hugging Face
OpenAI
OpenAI API
Claude LLM
Auth0
NLP
JSON Schema
Docker
Supabase
AI Engineer
Jan 2023 - Jul 20235 months
Project Overview

It's a personalized AI writing assistant that helps writers organize work, access their library, and receive tailored creative support with AI-powered features.

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Responsibilities:
  • Developed a proof-of-concept for a chat-with-your-data copilot to assist writers with personalized content retrieval and creative support;
  • Implemented an agent system architecture for specialized writing assistance tasks, including brainstorming, editing, and research;
  • Utilized advanced RAG techniques to enhance contextual understanding of user documents and writing style;
  • Integrated vector databases for efficient semantic search across personal document libraries and writing collections;
  • Leveraged LangChain and LlamaIndex frameworks to build modular, extensible components for document processing and conversation management;
  • Designed intelligent prompt engineering workflows to optimize agent responses based on user writing preferences and goals.
Project Tech stack:
LangChain
RAG
OpenAI API
OpenAI
Claude LLM
LLM
Mistral LLM
NLP
BERT
Pandas
Agile
Hugging Face
JSON Schema
Chat bots
Scikit-learn
Vector Databases
SQL
Supabase
Docker

Education

2019
Physics
Bachelor of Science
2025
Artificial Intelligence
Master of Science

Languages

Portuguese
Pre-intermediate
Spanish
Advanced
Italian
Advanced
Albanian
Advanced
English
Advanced

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