Curriculum Vitae and are alternate addresses of this page.

Self-Employed Freelance Software Engineer | Full Stack | Front & Back Experienced (18 years) | Seeking remote work job opportunity

Cover Letter


I am a software engineer in Seoul, the Republic of Korea. With M.S. degree in Department of Computer Science, M.S. in Department of Business Administration and much experience using many languages and frameworks to develop software applications, I am confident I will be an asset to my organization.

I enjoy being challenged and working on projects that require me to work outside my comfort and knowledge set, as continuing to learn new languages and development techniques are important to me and the success of my organization.

I am interested in data mining and machine learning.

Please feel free to contact me if you have any questions or comments. My email address is jongha.ahn (at) mrlatte (dot) net or me (at) jonghaahn (dot) com. I read everything sent there. Thanks.

M.S. in Computer Science MBA Software Engineer Artificial intelligence Big data Blockchain Mobile Android Web iOS Back-end Front-end Full Stack

Qualification Summary

  • Highly skilled in designing, developing and testing software.
  • Thorough understanding of data structures and algorithms.
  • Knowledgeable of front-end and back-end development best practices.
  • Much software troubleshooting experience.
  • Much experience from design to launch software.
  • Much experience developing with many languages and frameworks.
  • Developed software for over 10 million users.

Personal Identification

Education and Training

  • March, 2019 - August, 2020 B.S. degree in Department of Social Welfare, Examination for Self-Education
  • March, 2019 - present B.S. degree candidate in Department of Data Science and Statistics, Korea National Open University
  • August, 2015 - 2018 B.S. Dropped out of school, Department of English Language and Literature, Korea National Open University
  • March, 2012 - August 2015 M.A. degree in Department of Business Administration, Korea National Open University
  • March, 2009 - August 2011 M.S. degree in Department of Computer Science, The Graduate School of Information, Chung-Ang University
  • March, 1999 - February 2008 B.S. degree in Department of Computer Software, Gachon University (Kyungwon University)

Work Experiences

  • October 18, 2016 - present Freelance Software Engineer

    As a full-stack freelance developer, I develop mobile clients, servers and web applications. Are you looking for a software engineer? Please contact me.

  • August 3, 2015 - December 28, 2016 Eazler. Software Engineer, Founding member

    Eazler is a startup software company that developed business messenger in Korea. We have messaging and video technologies and have built mobile and web applications based on this. We have been selling mobile messenger to government agencies overseas.

  • February 17, 2003 - June 12, 2015 Division of S/W, ESTsoft. Software Engineer, Lead Programmer

    Since its inception in 1993, ESTsoft has been acknowledged as an inno-vation leader in software industry. ESTsoft pours every bit of effort to enhance the life quality through software innovation. Providing essential software products as in ALTools and InternetDISK, we are very responsive to meet custom needs. More than 90% of the PC users in Korea are using our product, ALToos. groups of our business software product, InternetDISK. CABAL Online, an MMORPG, have gained excellent reputations in the US, Europe and Asia as well as in Korea. For our global presence, we’re currenty working on ESTsoft America After establishment of ESTsoft Japan in 2007. ESTsoft was enlisted in KOSDAQ on July, 2008.

  • January 20, 2001 - February 14, 2002 Division of System Integration, Media SI Team, Comcast. Software Engineer

    Comcast is an Internet broadcasting service company based in Korea. I created an Internet broadcasting solution for Windows and a web application for Internet broadcasting. I also created an inventory management solution for warehousing and a barcode application for Windows CE. Comcast was enlisted in the OTC market.




  • Anomaly Detection based on Compression Data using Clustering Algorithm

    Jong-Ha Ahn. M.S. Thesis, Depart. of Computer Science, The Graduate School of Information, Chung-Ang Univ., 2011.

Korean Articles


  • 창업학

    디지털 콘텐츠 대여 커피전문점 창업 계획 사례(사업계획서):337-358, 2013년 2월;박춘엽.

    보명Books, ISBN 978-89-6366-072-1



  • Karma


    I developed a mobile messenger. This app supports end to end encryption, timer messages to enhance security, and encrypts files and videos for transmission. And the app also supports video and audio calls.

    Karmalab Inc., June, 2020 - December, 2020
    mobile messenger android encryption security video voice

  • Oilnow


    Based on Big Data Analysis and Algorithm Application, the app automatically recommends the closest and cheapest gas station near my location. This app helps you save on fuel costs by analyzing oiling patterns.

    Puzzles Ventures, December, 2017 - October, 2020
    kotlin android mobile gas-station

  • Oilnow owner

    Oilnow ownerOilnow ownerOilnow owner

    This app can be used as a push notification to see price changes at nearby gas stations. The app is available for weekly price trend in the list.

    Puzzles Ventures, February, 2020 - October, 2020
    gas-station gas kotlin mobile android software

  • Selecs Partner

    Selecs PartnerSelecs PartnerSelecs Partner

  • Kakao Sync1 integration and bridge implementation
  • Commerce API implementation
  • CMS Customization
  • Order information synchronization
  • </ul>

    <small>Maeil Dairies Co.Ltd, July, 2020 - Auguest, 2020</small><br /><span class="badge badge-light">web</span> <span class="badge badge-light">kakaosync</span> <span class="badge badge-light">php</span> <span class="badge badge-light">api</span> 
    <div class="clearfix"></div>
    • Park Hyatt Seoul

      Park Hyatt SeoulPark Hyatt SeoulPark Hyatt SeoulPark Hyatt Seoul

      Park Hyatt Seoul, Jun, 2020 - Jun, 2020
      web pdf hotel apm

    • Oakwood Premier

      Oakwood PremierOakwood Premier

      This is the site of the Oakwood Premier Hotel. I did the maintenance, fix bugs and improve features of this site. And I added function to check personal information processing policy and telecommunication business operator laws in this site.

      Oakwood Premier, Jun, 2020 - Jun, 2020
      web pdf hotel

    • Rootimpact


  • Technical SEO1 audits
  • Backlink audits
  • Local SEO
  • Link building
  • Indexation analysis and repair
  • Google penalty recovery
  • Keyword research
  • </ul>

    <small>Root Impact, May, 2020 - May, 2020</small><br /><span class="badge badge-light">web</span> <span class="badge badge-light">seo</span> <span class="badge badge-light">search</span> <span class="badge badge-light">google</span> <span class="badge badge-light">analysis</span> 
    <div class="clearfix"></div>
    • Chago


      This app is a quote comparison service when purchasing a new car. I applied Adbrix1 and Facebook SDK2 to this project and worked on optimizing the app.

    <small>Chago, March, 2020 - April, 2020</small><br /><span class="badge badge-light">objective-c</span> <span class="badge badge-light">java</span> <span class="badge badge-light">android</span> <span class="badge badge-light">ios</span> <span class="badge badge-light">mobile</span> <span class="badge badge-light">software</span> 
    <div class="clearfix"></div>
    • Supyrocks


      It is about online shopping malls. I customized the skin making work based on the godo mall. This project worked on a design like Google’s main screen.

      supyrocks, March, 2020 - May, 2020
      godo commerce html css

    • Elradio


      It is online shopping malls. I customized the skin making work based on the godo mall.

      Partina Group Seoul, February, 2020 - February, 2020
      godo html css mobile desktop

    • Dimeclub


      Maintenance works for dating app. It’s an app currently used by over a million people. This app includes real-time chat and recommendation features.

      dimeclub, February, 2020 - April, 2020
      java android ios objective-c mobile dating

    • Sweetco


      Rental car price comparison web application and mobile app. Stabilization and upgrade works. Bulk push feature upgrades and many service bug fixes.

      Sweetco, December, 2019 - January, 2020
      java android ios objective-c php mobile web

    • is a football coaching brokerage platform. Anyone can get coaching from a famous coach through uploaded video. Anyone with coaching skills can sell their products, and players can get coaching from famous coaches online.

      LAUM GmbH, April, 2019 - December, 2019
      brokerage platform node.js express backend frontend mobile desktop web scss

    • Wegen Scan

      Wegen ScanWegen ScanWegen Scan

      Wegen is a cryptograph wallet based on a block chain system. It includes the activation function using 3D security label made with ultra-thin nano process.

      Wegen, April, 2019 - July, 2019
      blockchain wallet kotlin android mobile

    • Moongkl Works

      Moongkl WorksMoongkl Works

      This is markup and publishing for the building homepage.

      Moongkl Works, June, 2019 - June, 2019
      writing letter web html javascript publishing

    • Fivesense

      Apps that could host the application on a web-based with native code from Android(Java) and iOS(Swift and Objective-C), and registered it in the Google Play and Appstore.

      Fivesense, March, 2019 - June, 2019
      android ios java objective-c swift mobile

    • Jaro


      Smart tape measure application for Android. Work for CJ proposal. Troubleshoot upgrading from BLE 4.0 to BLE 4.2

      Julda, March, 2019 - March, 2019
      ble bluetooth java android mobile

    • CLET


      CLET is a powerful cryptocurrency wallet and an easy ICO platform. Blind investment for token sales and ICO is coming to an end. Now you can raise profit with judgements and investments based on practical information. It is important for ICO projects to attract new investors. Entry barriers for the new investors should be lowered to encourage investments. Join a community that provides reliable information and easy participation of ICO investment, at CLET!

      Daily Token, May, 2018 - March, 2019
      blockchain wallet kotlin ndk android mobile

    • ESM (Sales Management System)

      ESM (Sales Management System)ESM (Sales Management System)

      This project is a web based sales platform development for bidding and placing orders. I have designed a special bidding and ordering algorithm for this project. I was all involved in the design and development of the entire platform.

      ESTsoft, January, 2017 - December, 2018
      sales management web software java spring mysql

    • CoinupTV


      CoinopTV is a web service that supports educational content related to block chains. This service supports live streaming integrated with YouTube services. Users can subscribe to this service.

      Delicon, April, 2018 - October, 2018
      blockchain lecture video html5 javascript node.js web mobile

    • UUNIO


      UUNIO is a blockchain-based Social Media Contents Market Place platform with an actual reward system. Users are remunerated for the entirety of the value that they create inside UUNIO. UUNIO is created for the decentralisation of information and equitable redistribution of value created by user contents.

      Daily Token, March, 2018 - April, 2018
      blockchain token node.js ejs scss javascript web

    • Sendlike


      Developing a dating app that open patterns that users have given scores.

      GoldFactory, March, 2018 - May, 2018
      kotlin android mobile

    • FastOrder


      FastOrder is an online order service using a smartphone. It also supports application for tablets that can be used in stores. This service can manage customers more efficiently without significantly changing existing store ordering system. I participated in ideation of service, service planning, design concepts, and prototyping. I have experienced while developing the services of the design planning services and business models.

      Fastlink Corp., March, 2018 - July, 2018
      order kotlin android mobile

    • Myriels


      The network map for your mobile contacts. The network map would be a visual guideline on designing your contact map. I implemented wi-tag feature on the network map. A Wi-tag is an anonymous tag that helps you better understand people on your contact map.

      Bodhic, December, 2017 - February, 2018
      java android mobile

    • Megapatrol Management System

      Megapatrol Management SystemMegapatrol Management System

      RF Card management system development. (Windows Application). MegaPatrol is management device which can supervise human’s activities especially for security guards to check whether they fulfill the patrolling work according to certain plan and rules. It’s easy and effective to control and track security guards’ activities.

      BioRF, December, 2017 - December, 2017
      visual-basic desktop windows

    • RisingStar


      It is a personal broadcasting service that supports live streaming. It is implemented as Android native using Kotlin. I have experienced with live streaming back-end building and protocol integration through this service.

      Delicon, November, 2017 - December, 2018
      java kotlin android node.js wowza firebase cloud storage firestore node.js mobile

    • Aston KYC & Management pages

      Aston KYC & Management pagesAston KYC & Management pages

      This is a website that supports cryptocurrency investments related to ICO (Initial Coin Offering). KYC (Know Your Customer), user wallet address authentication etc included.

      CERTON, December, 2017 - February, 2018
      express node.js html5 javascript pug less jquery css3 kyc web

    • Fresh Gourmet

      Fresh GourmetFresh Gourmet

      Fresh Gourmet is a company that cooks and sells lunch boxes. This is a web page that sells lunchboxes online as they expand their offline business online.

      Fresh Gourmet, October, 2017 - October, 2017
      html5 javascript jquery css web

    • T-messenger


      It is a mobile messenger for business use by the Oman government. The project uses WebRTC technology. I did the optimization work on this project for various network environments.

      WADI International, September, 2017 - September, 2017
      java android mobile

    • Ready U

      Ready UReady UReady UReady U

      An Android application that connects with people going to ski resorts. This app includes matching people, chatting, bulletin boards, and skiing skills.

      Ready U, September, 2017 - November, 2017
      kotlin android project management mobile

    • CashFeed


      CashFeed is a mobile flyer service that analyzes user patterns based on your location and recommends nearby stores. This app allows users to redeem points when they see the ad. The user can accumulate points and exchange them for goods.

      Delicon, September, 2017 - March, 2018
      java kotlin android mobile

    • MeBuy


      An Android application that curates PPL videos for real purchasing. Implemented hybrid application technology, video and content management technology.

      Delicon, July, 2017 - September, 2017
      java kotlin android web jade scss html5 javascript mobile

    • Chuze


      This service is predicts and recommends clothes that fit well with your physical information before purchasing clothes. The service basically recommends the optimal size of clothes for small and medium-sized brands based on large-sized clothes that fit well.

      Julda, July, 2017 - September, 2017
      vue.js html html5 css javascript mobile

    • Salalee


      An Android application to meet new people, invite friends and chat. In particular, this app can only be signed by employees of a certified company.

      GoldFactory, June, 2017 - September, 2017
      kotlin android mobile

    • Sleek Project

      Sleek ProjectSleek ProjectSleek Project

      This is a mobile app and a web project. The web application allows the user to select, schedule and pay for fitness programs. The mobile app application is an O2O service. The app can connect with users and trainers.

      Buddies, March, 2017 - September, 2017
      kotlin android html scss less mobile web

    • OTT(Over The Top) Service; Mug

      OTT(Over The Top) Service; MugOTT(Over The Top) Service; MugOTT(Over The Top) Service; Mug

      This app is an Android application that watches movies and TV. This app can be viewed or streamed online. The app implemented location aware technology using Wifi and multi-format streaming video playback technology.

      Delicon, February, 2017 - July, 2017
      java kotlin android ott mobile

    • Sales Management System

      A Web application based Java that manage sales, and order within the company. The service included an algorithm for calculating the sales priority.

      ESTsoft, February, 2017 - May, 2019
      java html html5 css javascript web desktop back-end front-end

    • Smart Tape Management; Jenda

      Smart Tape Management; JendaSmart Tape Management; JendaSmart Tape Management; Jenda

      An Android application that manages measurement by communicating with Smart Tape via Bluetooth. The app can connect with smart tapes to view, organize and share size data. Dimension management, Body shape management and smart tape measure data calibration algorithm added in Phase 2.

      Julda, January, 2017 - June, 2017
      java android mobile

    • Modify the Groupware in intranet for the mobile environment

      Modify the Groupware in intranet for the mobile environment

      Porting legacy groupware to mobile environment. The groupware for KCC group with over 4,800 employees.

      KCC, October, 2016 - December, 2016
      java spring mybatis tiles oracle javascript linux groupware jquery mobile web desktop back-end front-end

    • Comgree


      A messaging application for teams. The service is available online or on a standalone. Implemented in Java a Messaging Application which performs real-time messaging and chat for team. Along with three other team members who wrote the server, iOS and web application.

      Eazler, March, 2016 - December, 2016
      java android mobile

    • T-messenger


      It is a mobile messenger for business use by the Oman government. The project uses WebRTC technology. I did the optimization work on this project for various network environments.

      Eazler, Auguest, 2015 - March, 2016
      java android mobile

    • Tellustech


      This web service supports calibration equipment certification and certification application services. This web service supports multiple languages such as Korean and Vietnamese.

      Tellustech, March, 2015 - May, 2015
      java spring mybatis thymeleaf postgresql javascript grunt less coffeescript linux web desktop mobile back-end front-end

    • Doctor Implant

      Doctor ImplantDoctor ImplantDoctor ImplantDoctor Implant

      Implemented in Node.js Back-end Service and Back Office which supports API and consults management. Implemented in Java an Application which performs chat and consultation with dentists. Lead engineer on this product.

      ESTsoft, January, 2015 - March, 2015
      node.js grunt jade stylus android java express project manager mobile desktop back-end front-end

    • SkinDoc


      Implemented in Node.js Back-end Service and Back-office which supports API and consults management. Implemented in Java an Application which performs chat and consultation with dermatologists. Lead engineer on this product.

      ESTsoft, September, 2014 - December, 2014
      node.js grunt jade stylus android java express project manager mobile web desktop back-end front-end

    • Works for KISA; ISMS Certification

      Establish and deploy policies for development. Development process rehabilitation including configuration management and development history. Perform security tasks. Establish a standard process for the development team.

      ESTsoft, February, 2014 - April, 2014

    • Common forum system for mobile applications

      Implemented in PHP, AngularJS, C# and JavaScript an Application which performs Bulletin board system for Mobile application. The project was included as a hybrid mobile app. I shipped this product to over 5,000,000 customers in Republic of Korea.

      ESTsoft, February, 2014 - April, 2014
      php codeigniter angularjs mysql c# javascript bootstrap3 jquery linux windows lead mobile

    • Synchronized song lyrics system redesign

      Synchronized song lyrics system redesign

      Implemented in Java an Application which performs Real-time lyrics from mp3 files. I released this product to over 10,000,000 customers in Republic of Korea. Participated in this project as a Technical Architect.

      ESTsoft, February, 2014 - April, 2014
      java spring mysql apache solr linux project manager desktop windows back-end

    • Fast zip code search engine

      Implemented in PHP an Application which performs find zip code by address. Changed system and wrote code to improve performance of this engine, by over 100% better than the legacy system.

      ESTsoft, January, 2014 - January, 2014
      php mongodb c# linux lead programmer web back-end front-end

    • Redmine Sticky Messages plugin

      Implemented in Ruby a plugin for whole over 100 employees.

      ESTsoft, December, 2013 - December, 2013
      ruby html javascript jquery linux lead programmer back-end

    • Automated statistics tools

      Implemented in Selenium an Application with collects statistical data from the web automatically. Made this Application to reduce over 8 working hours a month to collecting statistics.

      ESTsoft, November, 2013 - November, 2013
      python selenium windows desktop lead back-end front-end

    • Mobile advertise and statistics system

      Implemented in PHP, C#, JavaScript and Hadoop an Application which analytics to measure applications and advertisement data to gain business insights. Lead engineer on this product.

      ESTsoft, October, 2013 - December, 2013
      php c# javascript html hadoop pig bootstrap3 jquery linux windows mobile lead programmer back-end front-end

    • ALSee for Windows 8.1 App

      ALSee for Windows 8.1 AppALSee for Windows 8.1 AppALSee for Windows 8.1 App

      Implemented in JavaScript and HTML5 a Application which animations, transitions, node nesting, layering, filtering and caching for images.

      ESTsoft, September, 2013 - October, 2013
      javascript html5 team leader desktop front-end

    • Cloud storage service; ALCloud

      Cloud storage service; ALCloudCloud storage service; ALCloudCloud storage service; ALCloudCloud storage service; ALCloud

      Implemented in Java an Application which unifies storage from multiple Cloud Services or Social Networking Services. Lead engineer on this product.

      ESTsoft, January, 2013 - October, 2013
      java spring mybatis mysql jquery javascript node.js linux lead programmer web back-end front-end

    • Infra service for ALTools

      Implemented in C#, PHP and Python a Application. Developed and managed updates for products that banners, advertisements system for applications with over 10 million users. Lead engineer on this product.

      ESTsoft, January, 2010 - June, 2013 c# php python mysql sql oracle flash flex javascript jquery windows linux team leader back-end front-end

    • BizHard


      Cloud storage and business environment service. Implemented in C#, C++, Java, Python and many other languages an Application which performs a cloud storage service, mail hosting, messenger, forum and mobile for iOS and Android. Lead engineer on this product.

      ESTsoft, January, 2008 - January, 2010 c# oracle flash flex python prototype jquery javascript team leader web back-end front-end

    • Human resource management system

      Implemented in C# an Application which performs HRM (Human resource management) and electronic approval system used by over 300 employees for the company.

      ESTsoft, August, 2007 - January, 2008 c# mysql javascript jquery html5 flash windows web back-end front-end

    • Security mail service for national institute

      Development security mail solutions for government used by national agencies.

      3Rsoft, July, 2006 - August, 2006
      java oracle javascript linux software engineer data modeling back-end front-end

    • Web application for game; Cabal Online

      Implemented in C# an Application which performs Member, Payment, Community and Forum services for Game. Lead engineer on this product.

      ESTsoft, June, 2005 - February, 2006 c# sql javascript windows team leader web back-end front-end

    • Content provider site for DRM Service; ALX

      Implemented in C# an Application which performs DRM(Digital rights management), Payment and Member services development. Lead engineer on this product.

      ESTsoft, April, 2005 - June, 2005 c# sql server javascript windows team leader web desktop back-end front-end

    • Online storage solution; InternetDisk

      Web application development and data modeling for online storage solution.

      ESTsoft, January, 2005 - April, 2005
      php mysql javascript linux desktop back-end front-end

    • Online storage service; IDisk

      Web application development and data modeling for online storage solution. This service was provided by major portal of the Republic of Korea.

      ESTsoft, February, 2003 - January, 2005 c# oracle javascript windows desktop back-end front-end

    • Inventory management system; Octopus

      Inventory management system for warehouse.Barcode scan and manage application using Windows CE.

      Comcast, January, 2003 - February, 2003
      embedded visual c++ 4.0 windows ce 4.0 stl desktop front-end

    • Web services for internet broadcasting

      Web application development for internet broadcasting system. Deployed in many public institutions in the Republic of Korea.

      Comcast, August, 2002 - January, 2003
      asp php javascript windows desktop back-end front-end

    • Personal live internet broadcasting system; MyPandora

      Personal live internet broadcasting system; MyPandoraPersonal live internet broadcasting system; MyPandora

      Development for private broadcasting solution. Implemented in MFC an Application which performs live video or audio streaming.

      Comcast, February, 2002 - August, 2002
      visual c++ visual basic asp windows linux desktop back-end front-end


    With commercial projects experience. (Alphabetical order)



    • 사회복지사 2급, 보건복지부
    • 정보처리기사, 한국산업인력공단
    • 사무자동화산업기사, 한국산업인력공단
    • 리눅스마스터 1급, 한국정보통신산업협회
    • 정보기기운용기능사, 한국산업인력공단
    • 웹디자인 기능사, 한국산업인력공단
    • 워드프로세서 1급, 대한상공회의소
    • 컴퓨터 활용능력 1급, 대한상공회의소
    • 전자상거래관리사 2급, 대한상공회의소
    • MCAS Master, Microsoft
    • GTQ 1급, 한국생산성본부
    • 유비쿼터스지식능력, 한국 RFID USN협회
    • 인터넷 정보관리사 전문가, 한국정보통신산업협회

    Completion of Courses

    • 이더리움 기반 스마트 컨트랙트 개발 과정 (1차), 한국인터넷진흥원, February 22, 2018 - February 28, 2005 (40 hours)
    • Biblical Financial Study, 크라운제정사역, May 3, 2015 (10 weeks)
    • 리더십 스킬과 테크닉, 한국능률협회, March 5, 2012 - March 7, 2012 (20 hours)
    • MS Core 마케팅, 삼성SDS 멀티캠퍼스, October 1, 2007 - October 31, 2007
    • e-MBA 전략경영(ver.2.0), 삼성SDS 멀티캠퍼스, September 1, 2007 - September 30, 2007
    • 관리자능력향상(EMC), 한국생산성본부, September 12, 2005 - September 14, 2005 (20 hours)


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    This page was last modified on 08 Aug 2019.