Backend Developer

Seoul (On-site) • Full-time

Infrastructure

Python

SQL

No-SQL

Back-end

Insights about this position

Visa sponsorship: No
The company cannot sponsor a Korean work visa for this role.
Korean language proficiency: Not required
No knowledge of Korean is required for this role.
Workplace type: On-site
Work is primarily performed at the office.

Hello, we are Retentics! We are an AI agent startup that helps US brands personalize their email marketing. Three weeks after our founding in December 2021, we secured seed investment from Kakao Ventures, and our total cumulative investment is 6 billion KRW.

After relocating our headquarters to the US in 2022 and going through several micro-pivot processes, we achieved remarkable results last year in 2025: average MRR growth of 30%, purchase conversion rate of 65%, and YoY customer retention rate of 99%. Our mission is to develop an AI Agent model that automates the entire customer lifecycle in the marketing space over the next 5 years.

What service does Retentics provide?

'Retentics' is a combination of 'Retention' and 'Analytics', and started as a customer churn analysis and management solution. We are now developing an AI agent model that automatically analyzes customer data to execute optimal timing and messaging in the email marketing space — the most widely used globally — and generates revenue without tedious operational work.

You can learn more about Retentics' services on the Retentics homepage.

We are looking for a Backend Developer to join Retentics. (4+ years of experience)

You will be responsible for stably operating Retentics' core SaaS product and handling scalability, efficiency, and optimization in line with our rapidly growing traffic and data environment.

Key Responsibilities

Design and operate data pipelines that stably process large-scale data
Develop and maintain backend services for web-based SaaS products
Optimize server environments so that machine learning models developed by data scientists run smoothly in production
Design and improve architecture with a focus on service stability and performance

Requirements

3+ years of backend development experience
Deep understanding of Python-based development and Docker (container environments)
Hands-on experience with key AWS services (Lambda, Step Functions, RDS, DynamoDB, ECS, S3, SNS, SQS, etc.)
Experience designing and building Serverless architecture
Experience designing and operating relational DBs (PostgreSQL, MySQL) and NoSQL (DynamoDB)
Experience building CI/CD pipelines based on GitHub Actions
Strong communication skills to collaborate with the team and solve problems
Ability to communicate in English for work purposes

Preferred Qualifications

Experience with e-commerce platform API (REST / GraphQL) integration such as Shopify, Cafe24, etc.
Experience using IaC tools such as Serverless Framework, Terraform, AWS CDK
Experience writing unit / integration / E2E tests using frameworks such as Pytest
Experience building and operating monitoring and logging systems such as AWS CloudWatch

Hiring Process

Document Screening → 1st English Interview (Skill Set) → 2nd Interview (Culture Fit) → Offer Meeting → Final Acceptance