Jonas KlimaitisPT

São Paulo

github.com/Jklimaitis

I build Python APIs and automations with a focus on predictability and scale. My foundation comes from years inside CRM and MarTech operations: connecting legacy platforms, handling data inconsistencies and keeping critical processes running.

Today I apply that support and engineering background to design backend systems that are ready for the real world from the start — thinking about the database, the infrastructure and the whole flow of information.

years in tech
6

What I work with

Backend

Python APIs with token authentication and hashed passwords.

  • Python
  • FastAPI
  • Django
  • REST APIs
  • JWT with refresh
  • bcrypt with pepper

Architecture

Layered code, with business rules kept out of the entry layer.

  • Layered architecture
  • SOLID
  • Clean Code
  • Decoupled services

Data

Relational modelling and queries on PostgreSQL, MySQL and Oracle.

  • PostgreSQL
  • MySQL
  • Oracle
  • SQL
  • Relational modeling

Infrastructure and DevOps

Containerised services and Linux deploys behind a reverse proxy.

  • Docker
  • Linux (WSL and Ubuntu)
  • Git and GitHub
  • systemd
  • nginx
  • Proxmox

Testing and quality

Automated tests with pytest and verification by execution.

  • pytest
  • API testing
  • Code review
  • Verification by execution

Other languages

They come in when the task goes beyond the backend: interface, operations script or automation.

  • Java
  • JavaScript
  • Node.js
  • React
  • Bash

Automation and AI

Automated flows with LLMs used as an engineering tool.

  • Process automation
  • API integration
  • Agent orchestration
  • Multi-agent on Slack
  • LLM as an engineering tool
  • Hermes Agent

Learning

What I already use while building projects, with study and feasibility work as I learn.

  • OAuth2
  • MongoDB
  • AWS
  • Microservices
  • TDD
  • UiPath

Projects

monolith · web

Projeto Carros

Web application for registering and managing vehicles, built with Python and Django on the Model-View-Template architecture. Access control and authentication protect the administrative and operational routes. Dynamic filters search vehicles by several criteria, and file upload stores the photos. Persistence and business rules rely on the Django ORM and strictly validated forms.

Architecture

  1. Templates (HTML5/CSS)
  2. Django Views (MVT)
  3. ModelForms (validation)
  4. Django ORM
  5. Database (PostgreSQL)

Highlights

  • Python and Django backend with the MVT pattern, separating presentation from models and rules.
  • Native authentication flow that restricts access and protects the editing forms.
  • Static file upload and management tied to the model lifecycle.
  • Search and filtering backed by optimised Django ORM queries.

Technologies

  • Python
  • Django
  • Django ORM
  • ModelForms
  • HTML5
  • CSS3
  • PostgreSQL

Python · updated Sep 2026

rest api · data

home_shopper

Asynchronous catalogue and shopping intelligence API on FastAPI and PostgreSQL, organised in decoupled service layers. It processes raw data from Brazilian electronic fiscal receipts (NFC-e) into a cross-store price history. Pydantic schemas validate inbound contracts and serialise responses. A pytest suite keeps the data pipeline stable.

Architecture

  1. NFC-e payload
  2. FastAPI Routers
  3. Pydantic Schemas
  4. ETL service
  5. PostgreSQL

Highlights

  • Layered FastAPI architecture with asynchronous I/O operations.
  • Dedicated ETL pipeline for normalising, deduplicating and storing NFC-e receipts.
  • Inbound and outbound contracts typed and validated with Pydantic at the edge.
  • pytest suite covering endpoints and transformation rules.

Technologies

  • FastAPI
  • Python
  • PostgreSQL
  • Pydantic
  • pytest
  • ETL
  • AsyncIO

Python

public MIT-licensed version; main development in a private repository

rest api · AI

Pimp My Commander

Asynchronous FastAPI application for recommending and building Commander decks in Magic: The Gathering. It integrates the Scryfall, EDHREC and ManaBox APIs to map the player collection and find statistical card synergies. Language models analyse archetypes and justify card swaps with context. Everything runs in Docker containers, which keeps the environment reproducible.

Architecture

  1. FastAPI Routers
  2. ManaBox Parser
  3. Gateways (Scryfall / EDHREC)
  4. LLM engine
  5. Docker

Highlights

  • Resilient external integration with Scryfall, EDHREC and ManaBox exports.
  • LLM orchestration to analyse context and recommend card substitutions.
  • Response contracts validated end to end with Pydantic.
  • Containerised environment with Docker for local and production runs.

Technologies

  • Python
  • FastAPI
  • Pydantic
  • Docker
  • LLM
  • HTTPX
  • REST APIs

Python · updated Oct 2026

devops · support

Central de Operações

Local portal that centralises technical procedures, publishes reports and tracks operational incidents. Fast search, severity filters and indexing support technical teams in real time. Delivery goes through a reverse proxy on Nginx with access control via basic authentication. The interface uses plain HTML, CSS and JavaScript, avoiding heavy dependencies and prioritising immediate load during incidents.

Architecture

  1. Nginx (proxy and auth)
  2. Interface (HTML / CSS / JS)
  3. Python service
  4. Local parser and logs

Highlights

  • Edge and security layer on Nginx providing basic user authentication.
  • Plain JavaScript frontend built for speed during contingency.
  • Local search and reactive filters to find routines and reports quickly.
  • Python scripts that read and consolidate incident files.

Technologies

  • Python
  • Nginx
  • HTML5
  • CSS3
  • JavaScript
  • Basic authentication

Python

reusable template with no history; the running installation is private

GitHub activity

live data · GitHub API

—contributions in the last year

~/portfoliogit log -5

  1. 2eca448feat: terminal com o git log do site na secao GitHub10-21
  2. a77fd88style: titulo da abertura ocupa a coluna10-21
  3. ac5c414fix: grade de repositorios sem buraco na ultima linha10-21
  4. 3e473bcfeat: arte do nome na abertura em canvas10-21
  5. b3d7a43feat: abertura em dois paragrafos e coluna de 54rem10-21

The data below loads in the browser from the public GitHub APIs. Without JavaScript, open the profile through the link.View GitHub profile

Journey

  1. Automation Analyst

    Jan 2025 to May 2026

    Netbiis

    • Customer journeys and marketing automation with segmentation, personalization and campaign rules.
    • Communication channels: email, SMS, push notifications and social media.
    • Integrations with Customer Data Platforms (CDP) and CRM systems.
    • Worked with Marketing, CRM and Technology teams to organise customer data and campaign requirements.
  2. Ads Technical Support Specialist

    2023 to Oct 2024

    Atento Brasil

    • Specialized technical support for Meta Ads campaigns.
    • Campaign performance analysis based on data reports.
    • Tracking setup with the Meta Pixel.
    • Resolution of complex technical issues in ads and campaign implementation.
    • Translation of technical information for non-specialist users.

Courses

Languages

Contact

Connect with me on LinkedIn and explore my projects on GitHub.