Senior Java Developer

Role Description

Join 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.

The 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.

• Design and implement a scalable event-driven communications platform
• Build highly reliable and fault-tolerant message delivery systems
• Manage large-scale real-time event processing pipelines
• Design and implement multi-channel delivery pipelines across email, SMS, voice, and push channels
• Handle compliance requirements, consent management, and communication policies
• Support emergency and high-priority notification workflows
• Implement provider failover and resiliency strategies to ensure delivery continuity
• Build tracking systems for delivery status, retries, and engagement events
• Design and implement observability, reporting, and analytics infrastructure
• Develop event processing and message orchestration workflows
• Implement provider integrations and external messaging service adapters
• Ensure system scalability, throughput, and performance under high load
• Collaborate with product and engineering teams on communication flows and requirements
• Contribute to architectural decisions and long-term platform evolution
• Ensure operational stability, reliability, and maintainability of the system

Qualifications

• At least 5 years of commercial software engineering experience
• Strong experience in Java development
• Proven experience designing and building high-scale messaging, notification, or communication platforms supporting email, SMS, push, or voice channels
• Strong experience integrating with CPaaS and messaging providers such as Twilio, SendGrid, Amazon SES, SNS, Firebase/APNs, Braze, Iterable, or OneSignal
• Solid understanding of event-driven architectures using Kafka, Pub/Sub, Apache Beam, Kafka Streams, Flink, or similar technologies
• Strong knowledge of message delivery semantics, including exactly-once or effectively-once processing, idempotency, deduplication, retries, and reconciliation
• Experience designing scalable streaming pipelines with support for backpressure, dead-letter queues, replay, ordering, and fault tolerance
• Hands-on experience building reliable provider integration layers with failover, rate limiting, webhook processing, and delivery tracking
• Strong understanding of messaging compliance requirements, including TCPA, CAN-SPAM, 10DLC, opt-in/opt-out management, suppression lists, and sender reputation
• Experience designing systems that protect sensitive customer data and minimize PII exposure
• Experience building priority-based delivery architectures for high-volume messaging platforms
• Strong understanding of scheduling and time-based delivery logic, including time zones, quiet hours, recurring schedules, and daylight saving time handling
• Experience implementing safeguards for large-scale messaging, including approval workflows, preview mechanisms, test modes, and blast-radius protection
• Experience designing delivery tracking, reporting, and analytics systems with accurate reconciliation across providers
• Strong knowledge of distributed systems, scalability, reliability, and high-availability architectures
• Excellent problem-solving skills with the ability to build highly reliable, fault-tolerant backend systems
• Upper-Intermediate or higher level of English

Requirements

• Experience with email/SMS deliverability and sender reputation management
• Understanding of A2P 10DLC registration and messaging compliance
• Experience with Voice & TTS solutions
• Knowledge of template management, content rendering, and localization pipelines
• Experience building scheduled or delayed delivery systems on cloud platforms (preferably GCP)
• Understanding of event schema design and idempotent event modeling
• Experience with BigQuery reporting and analytics
• Exposure to regulated environments (e.g., FERPA/COPPA, K-12, education)

Benefits

• Strong analytical and problem-solving skills
• Ability to work in distributed cross-functional teams
• Proactive approach to ownership and technical decision-making
• Strong communication and collaboration skills
• Ability to work in high-load, fast-paced environments
• Focus on reliability, scalability, and engineering quality