Back to About
Fajar Image

Fajar Saputro Juliantoro

Designer / Front-End

Fajar Saputro Juliantoro is a Senior Front-End Engineer with over 6 years of experience building fast, scalable, and user-focused web applications.

Specializing in React.js, Next.js, and TypeScript, he has led front-end initiatives at companies like Kobi Education and Quipper, dramatically improving performance, scalability, and UX.

Currently at Duonout, Fajar focuses on deep design-to-code execution and sharing real-world front-end insights with the developer community.
EmailWhatsAppLinkedInGitHub

Work Experience

Senior Front-End Engineer

Oct 2023 - Present

Kobi Education

Developing and maintaining Kobieducation.com, LMS, and eBook platforms. Improved performance, scalability, and implemented advanced unit testing with over 90% coverage using React.js, TypeScript, and Next.js.

Lead Front-End Developer

Jan 2024 - Present

PT. Duonout Solusi Digital

Co-founded a web design and development agency. We build custom websites, focused on performance and tailored client needs.

Senior Front-End Engineer (Quipper)

May 2021 - Sep 2023

Quipper

Developed and maintained Quipper.com. Increased performance by 40% and created scalable front-end infrastructure using Ruby on Rails, React.js, TypeScript, and Next.js.

Front-End Engineer

Aug 2020 - May 2021

99.co

Engineered property platforms for Rumah123.com and 99.co. Implemented a mobile-first strategy resulting in a 30% SEO boost and 25% enhancement in website speed.

Front-End Developer

Jan 2019 - Jul 2020

Clapping Ape

Developed web apps like Gredu.asia and Ottopay.id. Boosted mobile traffic by 40% and improved performance by 25%.

Front-End Developer

Jul 2017 - Jan 2019

41studio

Designed and developed web applications like Triv.co.id and Boatflow.jp utilizing Ruby on Rails and React.js.

Selected Works

High-Throughput Fintech Pipeline

Microservices

Decoupled reporting engine from core transactional service for Fintech apps. Implemented event-driven architecture using Kafka, allowing real-time balance updates without database locks.

Scaling EdTech & Assessment Platform

Architecture Setup

Scaled Kobi Education and Quipper. Migrated video delivery to a CDN, implemented aggressive Redis caching, and offloaded submission processing to background queues (AWS SQS).

Real Estate Marketplace Optimization

Front-End Architecture

Optimization for 99.co and Rumah123. Achieving a 30% increase in SEO performance, 25% enhancement in website speed, and seamless integration of new Next.js architecture.

Bank Partner Integrations Engine

API Integration

Created scalable integrations between Bank Partners (BCA, BNI, CIMB, Mandiri) with Jurnal (Mekari Cashlink Bankfeeds) handling massive daily transaction syncs.

Credit Scoring & Financial Services

Financial Technology

Developed and maintained full-stack digital financial services for Kredivo Group, optimizing core microservices for rapid user onboarding and loan processing.