👨🏻‍💻 postech.work

Junior Backend Developer - Java H/F

Lefty • 🌐 In Person

In Person Posted 1 week ago

Job Description

Context \& Mission

We are looking for a curious and rigorous

Junior Backend Engineer

to help design, build, and operate our

microservices

powering the Lefty platform. You’ll work primarily with

Java (21+)

and modern JVM tooling, build

gRPC/Protobuf

APIs consumed by our apps, and contribute to data-heavy services using

Elasticsearch

,

ScyllaDB

and

MariaDB

. You’ll collaborate with senior engineers, learn best practices, and take ownership of well-scoped features from design to production.

You’ll join an agile, ambitious team that values

technical excellence

,

observability

, and

reliability

. You’ll contribute to services that ingest and process large-scale social data, including features leveraging

open-source AI models

to enrich and classify content.

About the position

Design and implement services in Java:

Build well-structured, maintainable microservices with clean boundaries and clear domain models.

Define fast, typed APIs:

Ship and evolve

gRPC

services with

Protobuf

schemas. Keep contracts stable and backward compatible.

Search and storage at scale:

Model and query data effectively with

Elasticsearch

for search and

ScyllaDB

for high-throughput, low-latency workloads.

Quality and reliability:

Write unit and integration tests, participate in code reviews, and contribute to resilient, observable systems with logging, metrics, and tracing.

Operate what you build:

Help monitor production, debug incidents with teammates, and propose pragmatic improvements.

Collaborate cross-functionally:

Work closely with Product, Frontend, and Data to clarify requirements and deliver business value incrementally.

Build and test with Bazel:

Use

Bazel

as our build system for fast, reproducible, and scalable builds and CI. It’s a Google-grade toolchain that helps us keep builds hermetic and reliable.

Profile

We are looking for an engineer with

0–2 years of professional experience

in backend development.

Technical skills

Java fundamentals:

Solid understanding of modern Java features, concurrency basics, and the JVM ecosystem.

API development:

Experience building backend APIs.

Microservices basics:

Understanding of service boundaries, configuration, and inter-service communication.

Git:

Daily use of Git.

Soft skills \& mindset

Ownership / autonomy:

You follow through on your tasks, ask for help early, and care about the impact on users.

Learning mindset:

You’re eager to deepen your backend fundamentals and learn from reviews and pairing.

Pragmatism:

You balance iteration speed with system stability and maintainability.

Team spirit:

We’re a kind, supportive team that values a positive, energetic atmosphere. We help each other grow, celebrate wins together, and keep a good mood even when the problems are hard.

Nice to have

Exposure to

gRPC/Protobuf

.

Good knowledge of

SQL

and

Hibernate ORM

.

Datastores:

Familiarity with at least one of the following and readiness to learn both:

Elasticsearch, MariaDB

and

Cassandra/ScyllaDB

.

Testing:

Comfortable writing unit tests and basic integration tests.

CI:

Experience with CI pipelines.

Knowledge of

streaming

or

batch data processing

patterns.

Exposure to

AI/Open-source models

integration in backend services.

Interview process

HR call (10min)

Online coding test (\~30min)

Interview with CTO and a member of the tech team (\~1,5 hours)

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