Senior Software Engineer, Custody

At Keystone AI , we’re redefining access to financial services in a digital world. By combining the cutting-edge power of blockchain technology with everyday simplicity, we make digital currencies accessible and usable for all. As the world's largest network of cryptocurrency kiosks with over 40,000 locations nationwide, we're breaking down barriers to crypto adoption through our seamless mobile app, secure digital wallet, and DeFi integrations. Beyond our consumer offerings, we're also the infrastructure powering the crypto revolution for businesses. Through our enterprise Crypto-as-a-Service (CaaS) platform, we enable businesses to launch crypto capabilities in weeks, not months. Our modular, API-first infrastructure provides everything from KYC and payment processing to liquidity and custody solutions—all fully licensed and compliant. We’re big enough to lead the charge in decentralized finance but small enough that your ideas will make waves. Every role at Keystone AI contributes to building a financial future where everyone has the tools to thrive. At Keystone AI , your growth fuels our mission. Together, we RISE. Senior Software Engineer, Custody Build the on-chain transaction infrastructure that powers Keystone AI 's crypto payment rails- including the fulfillment pipeline, wallet orchestration, and settlement systems that move real money across chains at scale. You will accomplish this by working alongside your engineering team to build software and integrations for accepting, disseminating, and liquidating funds needed to fulfill customer transactions, including capabilities to custody, send and receive crypto funds. What You’ll Be Working On (Your Impact): Design solutions for complex technical and business problems Develop software systems and components for our rapidly growing business Write performant, maintainable code while iterating and shipping rapidly Work within our backend architecture and technology stack based on: Java 17 or higher with Project Reactor (Reactive Java) Spring Boot Command and Query Responsibility Separation (CQRS) architecture and Event Sourcing (ES) Full microservice environment RESTful APIs for synchronous flows Event-driven design (powered by CQRS and ES) for async flows Webhooks and Server-sent events Axon Framework for intra-domain event-driven design Kafka for inter-domain event-driven design Kubernetes, Helm charts, Argo platform MySQL DB Mongo DB AWS solutions (EC2, RDS, etc.) Author and maintain unit and integration tests Work with your Scrum team to plan sprints and delivery of features Drive engineering excellence, operational stability and security into all layers of the platform Participate in design and architecture discussions and planning Drive the execution and delivery of features by collaborating with cross functional stakeholders Work with Engineering Leadership to drive best practices in software development, testing, and production operations What We’re Looking For: Bachelor's degree in Computer Science, Software Engineering, or equivalent experience 6+ years of experience as a software engineer Experience building or maintaining on-chain transaction infrastructure, including transaction signing, broadcasting, confirmation tracking, and error/retry handling Experience building scalable services and distributed systems in Java or similar object-oriented language Experience driving technical designs within a team Experience writing code that is readable, scalable, and instrumented Experience working in a fast-paced Agile development environment Experience in communicating with users, other technical teams, and product to understand requirements, describe software product features and technical designs Required technology skills Java & Spring Boot expertise Experience with a microservice environment Kafka, RabbitMQ, ActiveMQ or similar tech RESTful APIs for synchronous flows MySQL DB Mongo DB or similar NoSql database Experience with Kubernetes or any cloud development platforms Not Required, But Nice to Have: Experience with wallet orchestration platforms (e.g. Fireblocks) or multi-wallet/multi-signer architectures Familiarity with gas management, fee estimation, or transaction queuing for high-throughput environments Experience with stablecoin rails or multi-chain settlement flows Familiarity with KYC/AML data flows or transaction monitoring integrations Understanding of treasury operations or liquidity management in a crypto context Experience or working knowledge of CQRS architecture and Event Sourcing concepts Experience with Event-driven design Webhooks, Server-sent events, Websocket or any async notification technology Axon Framework Check out our Keystone AI -AI-Usage-Guidelines-for-Candidates-10.2025.pdf" rel="nofollow ugc noopener noreferrer" target="_blank">AI Usage Guidelines to understand how we approach AI tools during the hiring process. Originally posted on Himalayas