Sr. Backend Engineer I - US Stocks

Founded to transform retail finance, Ajaib Group is an Indonesian fintech unicorn breaking barriers to financial access. Having recently secured a $270M Series C—the single largest funding round in Southeast Asia over the past four years—we are backed by premier global investors including Y Combinator, Ribbit Capital, SoftBank, and SBI Holdings.  

To build world-class products, we assemble world-class talent. Supported by our fully remote work arrangement, our team spans Eastern Europe, the Middle East, India, and Southeast Asia, allowing you to work with brilliant engineers and builders from around the globe from wherever you are. We operate with an impact-driven purpose where everyone is the owner of our customers' satisfaction. Driven by a growth mindset and a fierce will to win, we refuse to settle and constantly push engineering boundaries.

As a Sr. Backend Engineer I in the US Stocks team, you build and maintain the backend services that let Indonesian investors trade US stocks: orders, balances, market data, portfolio and corporate actions. You deliver well-defined features with high quality, grow quickly in system design, and help keep the platform accurate and reliable, including during US market hours. This role is designed for growth. You will be closely mentored by Tech Leads and Staff Engineers, with a clear trajectory toward Senior II, taking on increasingly complex architectural challenges and cross-team influence.

• Design, build and maintain backend services and APIs for US stock trading, funding and portfolio features.
• Deliver features from technical design to production, with tests, monitoring and alerting.
• Integrate with US brokerage and custody partners, and make those integrations handle failures, delays and duplicate messages safely.
• Make sure money, quantities, prices and currency conversion are handled accurately, with clear audit trails.
• Support reconciliation between our records and our partners' records, and help fix mismatches at the root.
• Write clean, well-tested code and take an active part in code reviews.
• Investigate production issues, find root causes and help ship lasting fixes.
• Work with Product, Operations and Compliance to turn requirements into reliable solutions.
• Learn to build and scale Smart Order Routing (SOR) logic, integrating with multiple Liquidity Providers (e.g., Alpaca) and handling complex order lifecycles and partial fills across different venues.
• Handle real-time market data streaming and manage strict rate limits across concurrent external partner APIs.

• Education: Bachelor's degree in Computer Science or equivalent practical experience.
• Experience: 4+ years of professional backend engineering, including running services in production.
• Languages: Strong in Java or Go
• System Design: Good understanding of microservices, REST/gRPC APIs, event-driven design and reliability basics.
• Data & Messaging: Hands-on with relational databases (query tuning), caching (Redis) and messaging (Kafka).
• Infrastructure: Experience with cloud platforms (GCP or AWS), containers and CI/CD.
• Mindset & Domain: Ownership mindset and clear communication. Experience in brokerage, trading, payments, cross-border money movement or another regulated environment is a strong plus.
• A fierce appetite for learning complex domain logic. Familiarity with modern API-first brokerages (e.g., Alpaca, DriveWealth) or the FIX protocol is a plus, but a proven ability to learn these systems quickly is required.