Back End Engineer

Location:

Type:

secondhand, first choice.

AI-native resale platform

mid level back end engineer

What you’ll do

• Develop Core Backend Services

  : Design, develop, and maintain production-ready Java 21 microservices using Spring Boot 3.x (Web, Security, Validation) for high-performance and scalable application functionality.

• Implement Cloud Persistence

  : Engineer efficient and secure data models and CRUD operations utilizing Google Cloud Firestore as the primary NoSQL data store.

• Integrate Third-Party APIs

  : Implement complex integrations, focusing on Firebase Admin SDK for authentication/security and the Stripe Java SDK for critical flows like Identity Verification and secure webhook processing.

• Develop REST APIs for Mobile Client

  : Design, implement, and optimize robust, secure, and scalable RESTful APIs to support all features of the mobile application.

• Ensure Code Quality & CI/CD

  : Write comprehensive unit and integration tests (JUnit 5, Mockito, Testcontainers with Firestore Emulator) and maintain code quality standards (Spotless) enforced via GitHub Actions CI pipelines.

• Maintain Security Posture

  : Ensure all API endpoints are secured using the custom Firebase ID token filter, enforce Token UID match, and handle sensitive data/webhook signatures securely.

• Collaborate & Optimize

  : Work closely with (ex-Atlassian) founders, participating in code reviews and optimizing services for performance and reliability.

Must-have (4+ Years Experience)

• Backend Expertise:

  Strong proficiency in

  Java 21+

  and extensive experience developing robust, scalable APIs with

  Spring Boot 3.x

  and the Spring ecosystem (Security, Web, Data).

• Cloud Persistence:

  Hands-on experience with

  Google Cloud Firestore

  or other NoSQL databases, including indexing and query optimization.

• API Integration & Security:

  Proven ability to integrate and secure external services, particularly

  Firebase Authentication

  and/or complex payment/identity platforms like

  Stripe

  .

• Testing & CI/CD:

  Proficient with unit and integration testing frameworks (

  JUnit, Mockito, Testcontainers

  ) and familiarity with continuous integration tools (

  GitHub Actions, Gradle

  ).

• Development Principles:

  Strong grasp of software design patterns, RESTful API design (

  OpenAPI/Swagger

  ), and adhering to strict code style and quality standards.

• Curiosity + willingness to

  learn new stacks

  quickly.

Preferred

• Kotlin DSL/Gradle:

  Familiarity with

  Gradle

  for build management, especially using the

  Kotlin DSL

  .

• Testcontainers:

  Direct experience utilizing

  Testcontainers

  for local, reliable integration testing against real services/emulators (e.g., Firestore Emulator).

• Microservice Architecture:

  Experience working within a microservices environment and understanding concepts like service discovery, configuration management, and distributed tracing.

• Security Deep Dive:

  Experience implementing advanced security features like API rate limiting, robust input validation, and secure handling of webhook signatures.

• Cloud Deployment/Infrastructure

  : Experience with deploying and monitoring services on Google Cloud or equivalent.

Why join us?

• Founding team mindset

  → This is not just another contract gig. You’ll be building alongside the founders and early hires, shaping how Toka works from the ground up.

• Contract-first, core intent

  → We start flexible, but the goal is clear: grow into the founding engineering team. Equity and long-term ownership are on the table if it’s the right fit.

• Collaboration at the core

  → We believe the best work comes from tight collaboration — async-first, transparent, and with everyone thinking like an owner.

• Impact that matters

  → Resale furniture is a $50B+ vertical waiting to be reinvented. Your work will directly reduce waste and carbon emissions at scale.

Let’s build the future of resale. 🌍