Esref Ozturk, Developer in Berlin, Germany
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Esref Ozturk

Verified Expert  in Engineering

Software Developer

Berlin, Germany
Toptal Member Since
February 8, 2018

Esref has been programming for several years now and has previously worked at Udemy. He's completing his master's degree in computer engineering at METU. Esref is eager to learn new things and is excited to work on fantastic, cutting-edge projects. He joined Toptal because he wanted to work with a broader clientele on international projects.


Drive Buddy
Machine Learning, Angular, MySQL, Django REST Framework, Django, Objective-C...
Amazon Web Services (AWS), React, Angular, Django REST Framework, Elasticsearch...




Preferred Environment

Git, Vim Text Editor, Linux

The most amazing...

...thing I've built is a sleep-tracking system that detects a user's sleep states and disorders like apnea.

Work Experience


2017 - 2020
Drive Buddy
  • Implemented car accident detection using machine learning.
  • Developed the Android and iOS SDK for collecting sensor data.
  • Built the driver score dashboard with Angular.
  • Implemented driver data and Score API with DRF.
Technologies: Machine Learning, Angular, MySQL, Django REST Framework, Django, Objective-C, Swift, iOS, Java, Android

Software Engineer

2016 - 2017
  • Researched and developed a search functionality for
  • Designed and developed REST APIs.
  • Wrote unit and E2E tests.
  • Implemented Elasticsearch cluster provisioning.
  • Maintained the Django code running on CentOS.
Technologies: Amazon Web Services (AWS), React, Angular, Django REST Framework, Elasticsearch, Django, Python

Software Engineer

2016 - 2016
STM Defence Technologies & Engineering, Inc.
  • Researched and developed an automated hardening platform for many systems including various operating systems (Windows, Linux, FreeBSD), web servers, and mail servers.
Technologies: Django, Python

Software Developer

2014 - 2016
Cyber Warfare Lab, Labris Networks
  • Researched and developed Labris UTM, a CentOS-derived Linux distribution designed for unified thread management.
  • Patched a web content filtering program with C++.
  • Designed and developed configuration system for high availability using Python.
Technologies: PHP, Unified Threat Management (UTM), LDAP, CentOS, PostgreSQL, Bash, Python, C++

Software Engineer

2014 - 2014
  • Developed sample Hazelcast integration modules for Hibernate second level cache and Spring.
Technologies: Spring, Hibernate, Apache Derby, Hazelcast, Java

Software Developer

2014 - 2014
TUBITAK (The Scientific and Technological Research Council of Turkey)
  • Developed a kernel module that provides multiple clipboards for Debian-based operating systems.
  • Wrote a configuration management script with Python.
  • Set up kernel hooks for detecting keyboard shortcuts.
  • Stored multiple clipboard items on Linux.
Technologies: X11, Kernel, Python, C

Software Engineer

2013 - 2013
Kovan Research Lab
  • Developed a web application that lets instructors prepare exams according to their preferred criteria.
  • Created an automatic PDF generator which uses LaTeX.
Technologies: LaTeX, MySQL, Django, Python, Ubuntu

A web application for playing chess that runs GNUChess in the background.

Technology Stack: Python, Django, JavaScript, Socket.IO

Book Chapter: Software-defined Network Security
I have written a book chapter about software-defined network security.

Abstract: The future networks are expected to lead a hyper-connected society with the promise of high social and economic value. The goal is to solve today's network problems and provide adequate security. Thus, future networks require a flexible infrastructure that is secure against cyber attacks. Software-defined networking (SDN) can be considered as one of the building blocks of upcoming networking technologies.

In this chapter, the limitations of today's networks are first presented. Then, solutions to secure the networks with SDN components are given. This concept is referred to as “SDN for Security.” While SDN facilitates securing networks in general, it introduces additional challenges, mainly, the vulnerabilities of the SDN components such as the controller have to be addressed. Security for SDN aims at securing SDN assets and is discussed in the sequel. After reading this chapter, readers will obtain a comprehensive overview of the limitations of traditional networks, such as how SDN overcomes those limitations and the security issues thereof.

Nano Duel: Crypto Token-based Gambling Website

I developed both back-end and front-end of the website from scratch. I also set up a nano server by myself to handle transactions and developed a dedicated transaction system for this website which was basically a primitive coin exchange system.

Technologies: Python, Django, Nano, Vue.js, Semantic UI, MySQL

Content Management System for Hospital Screens

Here, I developed a system where hospital staff can manage the content displayed on the screen throughout the hospital. The system also had the capability to give directions to patients.

Technologies: Python, Django, Django REST Framework, Angular, PrimeNG, MySQL

Crypto Metrics Delivery Platform

I have worked on a project for creating Crypto Data APIs. Data includes chain metrics like circulating supply and exchange metrics like volume data.

Technologies: Python, AWS (Lambda, CloudWatch, Redshift, S3, Kinesis Firehose, EC2), Crypto Exchange APIs, Blockchain Nodes

Equine (Horse) Fitness Tracker

I've worked on the maintenance and redevelopment of existing Equine Fitness Tracker apps for iOS and Android.

Technologies: Android, iOS, Java, Objective-C

This is a personalized sleep tracking and analyzing system that focuses on optimizing people's sleep.

Technologies: Deep Learning, Machine Learning, Big Data, Python, Django, JavaScript, Android, Arduino, Raspberry Pi

Multiclip | Multiple Clipboards
This is a kernel module that provides multiple clipboard capabilities using X11 on Debian-based operating systems.

Technology Stack: C, Kernel Hooks, Python

Deep Learning Social Media Comment Classification
This classifies user comments in social media groups with opposing views. The goal of this project is classifying user comments into social media groups with opposing views. In the scope of this project, comments on Turkish and English pairs of Facebook pages are classified with decurrent neural networks and convolutional neural networks.

Technologies: Deep Learning, LSTM, CNN, Keras, Python, Django

Integrity and Origin Authentication of QR Codes
I added an authentication layer to QR code encoding and decoding parts. It prevents man-in-the-middle attacks.

Technologies: Python, Cryptography, Asymmetric Key Encryption, RSA

PDF AutoBookmarker Application

I developed an application for Windows and Mac OS to add the table of contents bookmarks to PDFs automatically. I also developed a packaging system for both Windows and Mac OS.

Technologies: Python, wxPython, PDFMiner, PyPDF2


I developed a mobile application, called Photicon that detects what emotion is on your face and filters your photo by adding related emojis. It also gives a score for the emotion showing on your face. You can get great filters with emojis that shows your current emotion.

You can see your dominant emotion emojis and the percentage of each emotion. It eight different emotion categories.

Photicon detects the following emotions: happiness, sadness, fear, anger, surprise, disgust, contempt, and neutrality.

Photicon lets you use photos that contain more than one face. Get a photo of a group of people and let the Photicon handle it.

Technologies: iOS, Swift, Microsoft Emotion API


Wubble is a movie-themed social network built for Android.

Wubble has a Twitter-like user interface, where you can follow other users, send Wubbles, and read their Wubbles. You can share your thoughts about a movie via Wubble. You can follow people, read, like, dislike their Wubbles. You can start a discussion about a movie by commenting one of your friends Wubbles and see movie scores from different websites such as IMDB, Rotten Tomatoes, and Metacritic.

Technologies: Android, Java, Parse, Rotten Tomatoes, TMDb, OMDb

Color Crunch

Color Crunch is the simplest but the hardest game. All you have to do is match the colors with their names in a limited amount of time.

Technologies: Android, Java

Cubix Game | Cube Catch

This is a casual arcade-type game. Tap the right colored buttons when the cubes are in the middle of the rectangle.

Technologies: iOS, Swift

Space Utilization Visualization

I developed a website that shows off a room's assets (chair, table, and so on) using visualizations. A lambda function gets raw data from AWS S3 bucket and returns visualization data which is used by the static web page.

Technologies: AWS, Python, HTML, CSS, JavaScript, PowerBI, AWS Lambda, AWS ELB, AWS S3

Device Management System

I developed a web page for companies to manage their devices (computers, monitors, and so on). They can import users from Google Suite, then assign devices to them. They can also easily track all operations of devices on a dashboard.

Technologies: AWS, Python, Django, DRF, React, Docker, PostgreSQL
2017 - 2018

Google Developer Challenge Scholarship in Android Development

Udacity - Online

2016 - 2018

Master's Degree in Computer Engineering

Middle East Technical University - Ankara, Turkey

2011 - 2016

Bachelor's Degree in Computer Engineering

Middle East Technical University - Ankara, Turkey

2014 - 2015

Certificate in MCNA - Network (Fast)

METU Continuous Education Center - Ankara, Turkey


Google Developer Challenge Scholarship



MCNA — Network (Fast)

Middle East Technical University — Continuous Education Center


REST APIs, Django ORM, Facebook Open Graph API, Alamofire, React, Azure Blob Storage API, Node.js, Vue, CocoaPods


Apache, Vim Text Editor, NGINX, Gradle, PyCharm, Android Studio, Xcode, wxPython, Crashlytics, Git, AWS SDK, LaTeX, Travis CI


Django REST Framework, Django, Angular, Spring, Hibernate, ASP.NET MVC


C++, C, SQL, Python, Java, PHP, HTML5, HTML, JavaScript, Swift, Bash, Objective-C


Object-oriented Programming (OOP), Object-relational Mapping (ORM), Agile, REST


iOS, Android, Linux, Ubuntu, Apache2, Azure, Blockchain, CentOS, Kernel, Amazon Web Services (AWS), MacOS


JSON, MySQLdb, Elasticsearch, PostgreSQL, MySQL, NoSQL, Azure Blobs, Relational Databases, Hazelcast, Apache Derby


APIs, Ubuntu Server, Blockchain Development, Data Visualization, Data, Machine Learning, Lambda Functions, X11, Ajax, SMTP, Python Performance, Unified Threat Management (UTM), LDAP, Asymmetric Encryption, RSA, Cryptography, Cryptocurrency, Encryption

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