Job descriptionType:
6-Month Contract (targeted through September; extension possible but not guaranteed)
Location:
Downtown Toronto, ON
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Mon-Thurs Onsite (4 days/week), 37.5 hours/week
Collabera is seeking a
Senior Java Software Engineer
to support a large-scale
modernization initiative
focused on transforming legacy and third-party systems into scalable, cloud-based architectures.
This is a
high-impact, problem-driven role —not a ticket-based environment. The engineer will be expected to
own problem spaces end-to-end , contributing to system design, architecture decisions, and hands-on development.
The environment consists of a
fragmented ecosystem of 50+ legacy and internally built applications , requiring strong system thinking, data handling experience, and the ability to operate in ambiguity.
Day-to-Day Responsibilities
The Senior Java Engineer will focus on
designing and building scalable backend systems
while driving modernization efforts across a complex application landscape.
A significant portion of the role involves
analyzing, decomposing, and re-architecting legacy systems , including migrating workloads to AWS (EC2, RDS) and improving overall system performance, reliability, and maintainability.
They will build services responsible for
data ingestion, transformation, validation, and distribution , working with data-heavy workflows (including market data).
The engineer will also play a key role in
system design and architecture , making pragmatic tradeoffs (e.g., scalability vs simplicity) and ensuring solutions are production-ready.
Additional responsibilities include
troubleshooting complex production issues
(e.g., memory leaks, concurrency issues, latency bottlenecks), implementing
observability practices (logging, metrics, tracing) , and building
resilient systems
(retries, failure handling, circuit breakers).
The remaining portion of the role includes
collaborating with engineers and stakeholders , helping clarify ambiguous requirements, shaping solutions, and providing
technical leadership through code reviews and mentorship .
Must-Haves
8-10+ years of experience as a
Java Backend Engineer
Strong expertise in
Core Java
(collections, concurrency, JVM internals, memory model)
Experience with
performance tuning, garbage collection, and profiling
Hands-on experience with
Spring (Boot, MVC, Data)
and
Hibernate/JPA
Strong
system design and distributed systems knowledge
(caching, messaging, eventual consistency)
Experience with
AWS or cloud-based architectures
Strong
SQL and data handling experience
Proven ability to
troubleshoot complex production issues
Experience building systems
beyond simple CRUD APIs
(data pipelines, processing systems, etc.)
Ability to
operate in ambiguity and define solutions—not just execute tasks
Plusses
Experience with
data-intensive systems or data pipelines
Exposure to
microservices architecture
(Spring ecosystem)
Background in
capital markets / financial services
Experience
modernizing or replacing legacy systems at scale
Familiarity with
CI/CD pipelines and DevOps practices
We may use AI-enabled and/or automated tools to support parts of our recruitment process, including application screening, interview scheduling, and candidate communications. These tools are used to enhance consistency and efficiency. All hiring decisions involve human review and are not based solely on automated processing.
The Company offers a total rewards package in accordance with all applicable federal, provincial, and local laws and requirements. Benefit eligibility and offerings vary based on role, employment status, and work location. For contractor positions, benefits are limited to those entitlements and protections required by applicable law, which may include (as applicable) vacation pay, public holidays, leaves of absence, and other legally mandated benefits or payments.
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