Senior Java Developer

Google Chrome Microsoft Edge Apple Safari Mozilla Firefox Senior Java DeveloperFull-timeCompany DescriptionJoin a project where scalability, resiliency, and real-time communication are at the core of the engineering challenge. We are looking for a Senior Java Developer to help build a high-load multi-channel communications platform used to deliver critical notifications to millions of users worldwide.As part of Sigma Software, you will work remotely in an international engineering environment and contribute to the development of distributed, event-driven systems with complex delivery pipelines and fault-tolerant architecture.We at Sigma Software offer the opportunity to influence architectural decisions, work on long-term product development, and collaborate with experienced engineering teams building modern cloud-native solutions.CUSTOMEROur customer is a leading EdTech company that uses AI and data-driven technologies to personalize learning experiences, optimize user engagement, and improve marketing effectiveness through advanced audience targeting and analytics.PROJECTThe project focuses on building a modern multi-channel communications platform capable of delivering critical notifications across email, SMS, voice, and push channels at massive scale. The system supports automated workflows, emergency broadcasts, consent management, reporting and analytics, provider failover strategies, and real-time event processing.Job DescriptionDesign and implement a scalable event-driven communications platformBuild highly reliable and fault-tolerant message delivery systemsManage large-scale real-time event processing pipelinesDesign and implement multi-channel delivery pipelines across email, SMS, voice, and push channelsHandle compliance requirements, consent management, and communication policiesSupport emergency and high-priority notification workflowsImplement provider failover and resiliency strategies to ensure delivery continuityBuild tracking systems for delivery status, retries, and engagement eventsDesign and implement observability, reporting, and analytics infrastructureDevelop event processing and message orchestration workflowsImplement provider integrations and external messaging service adaptersEnsure system scalability, throughput, and performance under high loadCollaborate with product and engineering teams on communication flows and requirementsContribute to architectural decisions and long-term platform evolutionEnsure operational stability, reliability, and maintainability of the systemQualificationsAt least 5 years of commercial software engineering experienceStrong experience in Java developmentProven experience designing and building high-scale messaging, notification, or communication platforms supporting email, SMS, push, or voice channelsStrong experience integrating with CPaaS and messaging providers such as Twilio, SendGrid, Amazon SES, SNS, Firebase/APNs, Braze, Iterable, or OneSignalSolid understanding of event-driven architectures using Kafka, Pub/Sub, Apache Beam, Kafka Streams, Flink, or similar technologiesStrong knowledge of message delivery semantics, including exactly-once or effectively-once processing, idempotency, deduplication, retries, and reconciliationExperience designing scalable streaming pipelines with support for backpressure, dead-letter queues, replay, ordering, and fault toleranceHands-on experience building reliable provider integration layers with failover, rate limiting, webhook processing, and delivery trackingStrong understanding of messaging compliance requirements, including TCPA, CAN-SPAM, 10DLC, opt-in/opt-out management, suppression lists, and sender reputationExperience designing systems that protect sensitive customer data and minimize PII exposureExperience building priority-based delivery architectures for high-volume messaging platformsStrong understanding of scheduling and time-based delivery logic, including time zones, quiet hours, recurring...