Java Backend Developer Jobs

About Backblaze Backblaze provides reliable, high-availability cloud storage trusted by consumers, SMBs, enterprises, and developers in over 150 countries. Backblaze B2 Cloud Storage supports data-intensive workloads including backup, media, analytics, and modern AI pipelines. Our teams focus on building secure, durable, scalable systems with a strong emphasis on application security from day one and protecting customers to keep them safe. While there is a lot to celebrate in our past, there are greater opportunities ahead of us. About the Role We are seeking a Back-End Engineer for our Computer Backup Team. This team focuses on the services supporting our Computer Backup product. In this role, you will build and maintain systems to back up and restore exabytes of data. We are looking for an engineer who is excited to learn to develop high-performance, highly multithreaded architectures. We value versatility and are looking for someone comfortable designing and working across any technology as our needs evolve. Responsibilities Design and develop highly scalable, performant services and APIs in a Java ecosystem. Integrate AI coding agents and frameworks into your workflow to accelerate development, refactor legacy components, and improve code quality. Collaborate on the full technical lifecycle, including estimation, design, development, and delivery. Collaborate across the organization to ensure project success. You will often engage with QA, Data Centers, Marketing, Product Management, Support, Legal/Compliance, and Security to gather necessary context and requirements to implement solutions correctly, help customers, and solve problems. Diagnose complex issues and maintain the stability of large-scale production systems. Collaborate across functional teams and provide technical leadership to foster engineering excellence. Required Qualifications A broad track record of project deliveries and successfully shipping software systems. 3+ years of experience with Java

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Software Engineer or Senior Software Engineer to join the OEX Mobile Growth team in Singapore. The team operates at the intersection of mobile engineering, consumer growth, and product development. You will work closely with Product, Business Development, and regional market teams to build and improve growth initiatives that directly influence user acquisition, activation, conversion, and retention. This role is suited to an engineer who enjoys solving user-facing problems, working with data, and contributing ideas beyond implementation. You will have the opportunity to take ownership of projects from problem definition through launch, measurement, and iteration. What You'll Be Doing Design, build, test, and maintain reliable mobile growth features and supporting systems. Contribute across the full engineering lifecycle, from understanding business and user problems to implementation, launch, monitoring, and i

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About the Team The Exchange Middle Platform team develops the core modules of the exchange, including the matching engine, real-time market data streaming, and market data analysis. It is the backbone of our industry-leading trading product, used by millions of users. We are seeking highly motivated Java/C++ Engineers to join our cutting-edge team. In this role, you will design, develop, and optimize our systems, which are critical components of our technology stack. We leverage AI technologies to enhance efficiency and performance, offering a unique opportunity for individuals who are eager to learn and grow in a fast-paced, innovative environment. Candidates with prior experience in large internet companies will excel in this role, as they will bring valuable insights into building and maintaining high-performance, distributed systems. What You’ll Be Doing Design and implement innovative solutions for our full range of trading products including spot, future, perp

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity As a Technical Expert, you will own the core build-out of the Operations Automation & Cloud Management Platform, focusing on the unified management and intelligent orchestration of multi-cloud products . By integrating with cloud provider APIs (Aliyun, AWS, Azure), the role builds full-lifecycle management capabilities across compute, storage, network, database, and middleware resources—combined with CMDB, Event Center, orchestration engines, and AI / LLM capabilities—to evolve from manual operations toward intelligent control and automated change, continuously improving operational efficiency and stability. What You’ll Be Doing Design and develop the Operations Automation & Cloud Management Platform, building full-lifecycle management capabilities for multi-cloud resources across compute, storage, network, database, and middleware; Integrate with cloud provider APIs (Aliyun, AWS, Azure) and Terraform to enable unified on

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity As a Technical Expert, you will own the core build-out of the company's R&D Efficiency Platform, proactively identifying and eliminating risks across the delivery pipeline through CI/CD, DevSecOps, Change Management, and AI-Native upgrades—reducing delivery cost while improving quality and efficiency via platformization and automation. What You’ll Be Doing Build core capabilities of the R&D Efficiency Platform and onboard business systems to improve overall engineering efficiency and delivery quality; Design and optimize CI/CD pipelines (GitLab, Pipeline, ArgoCD), driving standardization, automation, and observability; Drive the AI-Native evolution of CI/CD , introducing AI Agent / LLM for intelligent code review, pipeline self-healing, smart test orchestration, and change-risk prediction; Build DevSecOps capabilities , embedding Shift-Left Security across the lifecycle with SAST, DAST, SCA, image/secret scanning, and sec

OKX will be prioritising applicants who have a current right to work in Hong Kong, and do not require OKX's sponsorship of a visa. Please note that Hong Kong is a group-level service hub, and OKX does not carry on a business of operating a virtual asset trading platform in Hong Kong. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Senior Staff Mobile Engineer to join our P2P & Fiat team, where you will own the mobile engineering for OKX’s peer-to-peer trading and fiat payment experiences across multiple markets. This is a high-ownership role sitting at the intersection of mobile engineering and cross-border payments—you will work closely with compliance, legal, and regional business teams to build localised, regulation-aware payment flows for users across Southeast Asia, LATAM, MENA, and beyond. You bring deep familiarity with P2P trading mechanics, cross-regional fiat payment integrations, and the compliance considerations that govern them. You are also fluent in AI-assisted development and bring the discipline to build, maintain, and continuously improve your own AI engineering workfl

OKX will be prioritising applicants who have a current right to work in Hong Kong, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Senior Staff Mobile Engineer to join our OEX Mobile Growth team — a pure mobile team sitting at the intersection of engineering rigour, consumer growth craft, and product instinct. This is not a feature delivery role. You will own the client-side architecture for new user acquisition, referral and virality mechanics, and the reward and conversion funnels that drive growth for millions of users. You bring deep expertise in mobile attribution — from MMP design and evolution through to anti-fraud, channel revenue sharing, and ROI evaluation — and you know how to turn attribution data into decisions. You are also fluent in AI-assisted development and bring the discipline to build, maintain, and continuously improve your own AI engineering workflows. What You'll Be Doing Own the client-side architecture for core growth conversion flows — new user acquisition, referral and virality loops, reward mechanics, and act

OKX will be prioritising applicants who have a current right to work in Hong Kong, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Senior Staff Mobile Engineer to join our Mobile Infrastructure team, the foundational engineering group that powers the OKX app for millions of daily active users. This is not a feature delivery role. You will work at the platform layer, building the tools, frameworks, and systems that enable product engineering teams to move faster, ship higher quality code, and scale reliably. You are deeply native in either iOS or Android, and confident contributing across both platforms leveraging AI coding tools to move fluidly between stacks. You care about engineering quality at the foundation level: architecture, performance, toolchain, and developer experience. What You'll Be Doing Build and maintain mobile infrastructure, tooling, and shared frameworks that improve engineering efficiency and developer experience across the organisation. Analyse and optimise application code at the UI and infrastructure layer, includi

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Senior Staff Mobile Engineer to join our Mobile Infrastructure team, the foundational engineering group that powers the OKX app for millions of daily active users. This is not a feature delivery role. You will work at the platform layer, building the tools, frameworks, and systems that enable product engineering teams to move faster, ship higher quality code, and scale reliably. You are deeply native in either iOS or Android, and confident contributing across both platforms leveraging AI coding tools to move fluidly between stacks. You care about engineering quality at the foundation level: architecture, performance, toolchain, and developer experience. What You'll Be Doing Build and maintain mobile infrastructure, tooling, and shared frameworks that improve engineering efficiency and developer experience across the organisation. Analyse and optimise application code at the UI and infrastructure layer, includi

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity We are looking for a Senior Staff Software Engineer to join the OEX Mobile Growth team — a pure mobile team sitting at the intersection of engineering rigour, consumer growth craft, and product instinct. This is not a feature delivery role. You will sit upstream of requirements, shape initiatives alongside product and business stakeholders, and own the engineering end-to-end on growth bets that move real metrics for millions of users. The ideal profile combines a solid engineering foundation, hands-on growth experience serving mobile users, and the conviction to bring proposals, not just execute them. What You'll Be Doing Own the full engineering lifecycle of mobile growth initiatives - from shaping the brief with product and business through to production launch and iteration. Build and optimise growth systems - including funnel instrumentation, referral mechanics, acquisition loops, and experiment frameworks — directly serving t

Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Opportunity The Compliance team's primary objective is to ensure that OKX operates in accordance with regulatory requirements while maintaining the highest ethical and moral standards. The team owns the full compliance engineering stack: KYC onboarding and refresh, sanctions / PEP / adverse-media screening, transaction monitoring (TM) and travel-rule enforcement, case management, and regulatory reporting. We achieve this by developing compliance service solutions, integrating with KYC & AML vendors, and enabling robust business growth, which ultimately strengthens user trust in our platform. Our ultimate goal is to create a culture of compliance excellence, where innovation and responsible business practices are seamlessly integrated. In compliance, a system that is mostly right is wrong — so every control we build must be deterministic in its enforcement, complete in its coverage, and explainable in its outcome. What You’ll Be Doing Formulate, select, and develop technical schemes for platform projects across the compliance domain — KYC onboarding flows, identity v

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About the team: OKX data team is responsible for the whole data scope of OKG, from techincal selection, architecture design, data ingestion, data storage, ETL, data visualization to business intelligence and data science. We are data engineers, data analysts and data scientists. The team has end-to-end ownership of most of the data at OKx throughout the whole data lifecycle including data ingestion, data ETL, data warehouse and data services. As a data engineer of the team, you will work with the team to leverage data technologies to empower evidence-based decision-making and improve the quality of the company's products and services. Responsibilities: Proficient in mainstream cloud computing and big data technologies such as Hadoop, Hive, Flink, YARN, Elasticsearch (ES), Kafka , etc. Expert in real-time big data processing using Flink , with solid experience in Flink SQL development . Build and optimize offline and real-time data pipeline

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa About OKX At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About the team The Growth Team at OKX is a dynamic group of professionals dedicated to accelerating OKX’s expansion through innovative strategies, data-driven insights, and continuous optimization. By tackling intricate business logic at scale, tapping into emerging DeFi growth opportunities, and addressing globalization and localization challenges, the team drives impactful user acquisition, engagement, and retention across global markets Responsibilities Collaborate with Product, Design, and Marketing teams to deliver rapid, cross-functional innovation Architect and maintain high-performance, highly available distributed services Explore emerging opportunities in DeFi to promote growth and bridge centralized and decentralized solutions Solve complex business logic challenges and drive improvements for global user experiences Provide guidance on best practices, conduct peer code reviews, and champion continuous improvement Requirements Bachelor’s degree in Science, Techn

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa About OKX At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me, Do the Right Thing, and Get Things Done. These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About the Opportunity The Trading Service team is the backbone of our exchange's industry-leading trading product, which is utilized by millions of users. We are responsible for the core order and position management systems, enabling a full spectrum of trading products, including manual, automatic, and social trading, as well as brokerage services. Our platform supports diverse financial instruments such as spot, margin, futures, options, and perpetuals. Join our elite Trading Service team as a Senior Staff Software Engineer, where you will be a pivotal technical leader shaping the future of our ultra-low latency, high-throughput trading platform. This is a highly impactful individual contributor role for an exceptional engineer with a deep passion for financial markets and cutting-edge technology. You will own and drive the architectural direction for critical system components, solve the most complex technical challenges across multiple teams, and significantly in

OKX will be prioritising applicants who have a current right to work in Singapore, and do not require OKX's sponsorship of a visa. Who We Are At OKX, we believe that the future will be reshaped by crypto, and ultimately contribute to every individual's freedom. OKX is a leading crypto exchange, and the developer of OKX Wallet, giving millions access to crypto trading and decentralized crypto applications (dApps). OKX is also a trusted brand by hundreds of large institutions seeking access to crypto markets. We are safe and reliable, backed by our Proof of Reserves. Across our multiple offices globally, we are united by our core principles: We Before Me , Do the Right Thing , and Get Things Done . These shared values drive our culture, shape our processes, and foster a friendly, rewarding, and diverse environment for every OK-er. OKX is part of OKG, a group that brings the value of Blockchain to users around the world, through our leading products OKX, OKX Wallet, OKLink and more. About The Team The Service Stability Engineering Team envisions service stability as one of the core competitive strengths of the company's products. By building end-to-end, link-level risk management capabilities, the team aims to achieve sustainable automatic identification and analysis of stability risks, transforming from "reactive governance" to "proactive governance." This approach shifts more stability-related matters forward and addresses them early, preventing issues before they arise and enhancing user experience. What You’ll Be Doing Identify system risks, and improve the end-to-end performance and stability for the company's products. Lead infrastructure optimization, streamline R&D processes, and implement platform-based solutions. Explore new technologies, tools, and architectural patterns to continuously enhance the stability framework. What We Look For In You Bachelor's degree or higher in Computer Science or a related field, with over 7 years