Daniel – Python, LLM, RAG, experts in Lemon.io

Daniel

From Brazil (UTC-3)flag

AI Engineer|Senior

Daniel – Python, LLM, RAG

Daniel is a Senior AI Engineer with ~10 years of Python experience and a strong production track record in conversational agents and applied LLM systems. He's built and shipped autonomous WhatsApp sales agents, RAG/GraphRAG pipelines, and eval harnesses in fintech and startup contexts — with measurable business outcomes (2× conversion over human agents). His earlier background spans data streaming (Kafka/Spark/Flink) and cloud-native infrastructure, giving him unusual depth across the full data and AI stack. Self-sufficient solo engineer who has hired and mentored other AI engineers; comfortable owning end-to-end from architecture to production observability.

11 years of commercial experience in
AI
Data analytics
Fintech
Enterprise software
SaaS
Main technologies
Python
10 years
LLM
4 years
RAG
4 years
AWS
5.5 years
Additional skills
LangChain
Grafana
Prometheus
LangGraph
MongoDB
FastAPI
RabbitMQ
OpenAI
Claude Code
Django
Neo4j
PostgreSQL
DigitalOcean
Jenkins
Apache Kafka
Docker
Terraform
Kubernetes
Apache Spark
Apache Flink
Machine learning
Vector Databases
Direct hire
Possible
Ready to get matched with vetted developers fast?
Let’s get started today!

Experience Highlights

Senior AI Engineer
Oct 2024 - Ongoing1 year 9 months
Project Overview

An autonomous conversational sales agent deployed over WhatsApp to qualify and close cold outbound leads for a public-servant loan product. The agent handles multi-product flows, simulates loan terms in-process, and hands off to human agents at the documentation stage. Achieved ~2× the human agent conversion rate (~5% → ~10%) in production.

Responsibilities:
  • Designed and deployed a production LangGraph-based conversational agent over a WhatsApp → RabbitMQ → AWS pipeline, with phone-number-keyed state checkpointing for stateful multi-turn conversations.
  • Implemented an intent router with hardcoded FAQ responses for high-frequency queries, avoiding LLM cost and latency on common turns and reducing per-conversation token spend.
  • Built in-process loan simulation tools to bypass a timeout-hostile async vendor API, enabling real-time product calculations mid-conversation.
  • Doubled cold-lead conversion rate from ~5% (human agents) to ~10% (AI agent) as the sole developer; instrumented funnel events to surface the delta to stakeholders.
  • Built a mixed eval harness — deterministic code assertions (e.g., scam-concern guardrail checks) plus LLM-as-judge for structured refusal quality — with CI integration and ~15-run pass-rate statistics per case.
  • Integrated Opik for end-to-end LLM tracing; applied prompt-prefix caching discipline (stable system prefix, variables appended) to control costs while validating model value.
  • Added Grafana dashboards tracking LLM response time by negotiation stage and error rate via Prometheus and OpenTelemetry.
  • Developed a custom Claude Code skill to automate eval generation, programmatically scaling test suites before each deployment.
  • Conducted a feasibility study on LLM fine-tuning, evaluating dataset volume requirements and use-case fit against RAG and prompt engineering alternatives.
Project Tech stack:
LangGraph
RabbitMQ
MongoDB
Claude Code
Grafana
Prometheus
AWS
OpenAI
FastAPI
Python
Full-Stack / AI Engineer
Jul 2023 - Oct 20241 year 3 months
Project Overview

A conversational AI assistant built on a full-stack Next.js and Django application. The system incorporated RAG and GraphRAG pipelines for document-grounded responses over a hybrid PostgreSQL/Neo4j knowledge store, plus TTS integration for voice output.

Responsibilities:
  • Architected RAG and GraphRAG pipelines using PostgreSQL (pgvector) and Neo4j, enabling both vector-similarity and graph-aware retrieval for document-grounded conversational responses.
  • Integrated TTS for voice output, extending the conversational interface beyond text interactions.
  • Built and deployed the full-stack application — Django REST backend, Next.js frontend — on AWS as the sole developer, from initial design through production deployment.
  • Drove AI feature decisions independently in a greenfield ambiguous environment, moving from research prototypes to integrated production features.
Project Tech stack:
RAG
OpenAI
PostgreSQL
Neo4j
Next.js
Django
AWS
Python
Full-Stack / AI Engineer
Feb 2021 - Jul 20232 years 5 months
Project Overview

An internal documentation chatbot built on RAG and a semantic search feature integrated into a live production application, developed within a software consultancy serving diverse global clients. Also included an ML regression model and a feasibility study on SLMs for on-device inference.

Responsibilities:
  • Built a semantic search capability for a live production application using OpenAI embeddings and similarity search; prototyped a RAG-based documentation chatbot over internal knowledge bases.
  • Conducted a feasibility study on small language models (SLMs) for on-device inference, evaluating latency and quality trade-offs against API-hosted LLMs.
  • Delivered a 61% improvement in predictive accuracy over the prior baseline with a machine learning regression model.
  • Owned full-stack development across React and Django — from feature implementation through production deployment on AWS and DigitalOcean, with CI via CircleCI.
Project Tech stack:
RAG
OpenAI
Django
React
AWS
PostgreSQL
DigitalOcean
CircleCI
Python
JavaScript
Software Engineer
Mar 2019 - Feb 20211 year 11 months
Project Overview

A cloud-native infrastructure platform and real-time event processing stack built within a large financial institution's innovation unit. Combined IaC-provisioned Kubernetes clusters with stream processing and Complex Event Processing (CEP) pipelines — an early-stage validation of patterns that predated mainstream cloud-native adoption.

Responsibilities:
  • Built real-time stream processing and CEP pipelines with Apache Kafka, Apache Flink, and Apache Spark to validate data-driven business hypotheses at banking scale.
  • Architected IaC-based provisioning and CI/CD pipelines using Terraform, Ansible, and Jenkins — adopted ahead of industry standardization.
  • Evaluated and integrated Prometheus, Grafana, and Elasticsearch for infrastructure and pipeline observability.
  • Turned high-level innovation mandates into working prototypes, bridging strategy and execution in an R&D-focused team.
Project Tech stack:
Apache Kafka
Docker
Kubernetes
Jenkins
Ansible
Prometheus
Grafana
Terraform
Python

Education

2015
Computer Engineering
Bachelor's

Languages

English
Advanced

Hire Daniel or someone with similar qualifications in days
All developers are ready for interview and are are just waiting for your requestdream dev illustration
Copyright © 2026 lemon.io. All rights reserved.