Вакансии Backend Developer

Blackthorn Vision is looking for a Junior Strong/Middle .NET Engineer. Our client, established in 2011 and based in Colorado, is a leading player in the U.S. application management market. We’ve had a successful partnership with this client and are seeking candidates who are eager to take ownership and improve a product already trusted by over 6,000 enterprises.

Requirements:

• 2+ years of commercial experience working on the backend as a .NET developer;
• Cloud systems development experience;
• Understanding of data access technologies, including Entity Framework and MongoDB;
• Experience with NoSQL databases;
• Experience with microservice-oriented architecture, parallel, and asynchronous programming design patterns;
• Experience with Kubernetes, Docker, and RabbitMQ;
• Proven experience with Azure technologies: Azure Entra id, Azure Storage accounts, Azure service bus, Azure container registry;
• Knowledge of design and architectural patterns.

Responsibilities:

• Develop and maintain high-quality software solutions using .NET 8.0;
• Take full ownership of delivering new features to end users, including designing architecture, implementing, testing, and onboarding the customer support team with new functionality;
• Collaborate with product owners, the support team, and end users to understand project requirements and deliver solutions;
• Participate in code reviews to enhance overall code quality;
• Ensure applications are high-performing, responsive, and of excellent quality;
• Troubleshoot and resolve technical issues and defects promptly;
• Create code documentation, technical specifications, and architecture diagrams for new features;
• Follow agile methodologies and participate in regular sprint planning and review meetings.

You are compatible with us if you:

• Have a proactive approach to taking ownership of decisions/features;
• Possess a strong, curiosity-driven mindset;
• Are comfortable with challenges;
• Have the ability to collaborate and build relationships with diverse personalities;
• Demonstrate customer-focused decision-making;
• Exhibit clear and timely communication;
• Are open to giving and receiving constructive feedback;
• Value the quality of your code;
• Are able to solve the required technical tasks and communicate throughout the process (for example, asking clarifying questions promptly).

Ciklum is looking for a Senior Python Developer to join our team full-time in Ukraine.
As a Senior Python Developer, become a part of a cross-functional development team engineering experiences of tomorrow.
Our Client is changing how organizations protect their data centers and clouds from advanced threats – and that starts with our people. Our team has some of the most talented experts in the field. We’re always looking for new people to challenge us, inspire us, and make us better. We solve a few of the most complex technological problems out there and build the market’s most comprehensive Data Centers cybersecurity solution. We work in small teams to allow each to make a real impact on our future product.
We are looking for a Senior Python Developer to join the Production Experience (ProdEx) team on a full-time based in Ukraine. Our excellent team is responsible for developing apps and pipelines to allow the client release faster and scale in the number of customers. We design, develop, maintain and deploy our tools to serve a wide range of needs. These tools can be used by internal users as well as by external customers generating an incredible impact in the whole organization.
Our tech stack consists of: Python, CircleCI, a variety of DBs, Jenkins, Kubernetes, Terraform, Ansible, public clouds and more. It’s a team that is facing the core challenges of our business today and keeps a fun and friendly atmosphere.

Responsibilities

• Design, develop, maintain and deploy our tools to serve a wide range of needs
• Develop products to allow faster-release and scale in the number of customers
• Manage integrations with the biggest cloud providers in the market
• Improve production reliability and maintainability

Requirements

• At least 4+ years of experience in Software development with Python. If you have experience with either Django/Flask/FastAPI, even better
• Experience with at least one cloud architecture such as GCP/AWS/Azure
• Experience with Docker
• Knowledge of Infrastructure as Code such as Terraform
• Knowledge of configuration management tools such as Ansible
• Basic knowledge of networking
• Excellent troubleshooting and problem-solving skills
• B.Sc in computer science or related degree – advantage

Our client is a crypto platform that enables institutions to participate in digital assets through custody, staking, trading, governance, settlement, and the industry’s leading security infrastructure.
Project stack: Golang, Docker, Kubernetes, GCP

Requirements:

• Proficient in Golang
• Experience with gRPC, Docker, Kubernetes, and GCP
• Strong understanding of wallet functionalities, including: how signing works and parameters needed to ensure validity on-chain (e.g., replay protection, fees, interactions with accounts/programs/coins)
• Node-based scanning processes for retrieving account info, balances, transactions, block events, and mapping these to balance changes
• Ability to navigate and understand open-source code, especially for protocol-level integrations.
• Skilled in writing efficient, isolated tests and familiar with CI/CD tools to ensure test pass rates

Responsibilities:

• Write clean, well-documented, and readable code
• Address feedback on pull requests efficiently
• Develop isolated tests and ensure code passes through CI/CD pipelines.
• Debug issues effectively to identify root causes across various environments.
• Ensure live systems and testing stages function as expected without regressions
• Work on wallet-related functionalities
• Implementing secure signing mechanisms
• Ensuring validity on-chain with replay protection and proper fee handling
• Direct scanning from nodes for account and transaction data
• Adapt integration strategies based on insights from open-source protocol code

We are looking for a part-time PHP developer.

About the project:

The Client is a card transaction processing company that provides services to banks and other state or commercial companies within Ukraine and abroad. The project offers payment solutions, such as money transfers, POS services, ATM monitoring services, etc.
The system accepts payments by payment cards and e-wallets and provides convenient tools for the development of e-commerce. Whatever business you have – online, offline, or on mobile – launch an online store or a mobile application, issue an invoice, or arrange for subscription services – the platform will help with any task. In addition, the team works on separate services for Merchant control, simplified flows to process the payments, etc.

Requirements:

• At least 2 years of experience;
• PHP 8.4;
• SQL;
• JavaScript;
• HTML/CSS;
• Experience with updating plugins.

Will be a plus:

• Experience with plugins development;
• At least Intermediate English.

Responsibilities:

• Update the payment plugin for Magento to 2.4.7;
• Update the payment plugin for Joomla to 5.1.0;
• Update the payment plugin for PrestaShop to 8.1.6.

We’re looking for a Senior Java Back End Engineer. Reporting to the Manager of Software Engineering, you’ll play a pivotal role in advancing the impact of our AdTech platform and delivering critical projects that bring significant value to operations. As a strong individual contributor, you will design and develop scalable systems, working directly with the architecture team and advising on broad technical decisions that impact our back-end tech stack. You will collaborate across technical pillars and provide expertise to guide junior team members, ensuring adherence to best practices through rigorous code and tech spec reviews.

About the project

illumin is a unique journey-based advertising platform that combines media planning and buying in an interactive and intuitive interface. It allows users to:

• Drag and drop audiences, creatives, and conditions onto a single-screen canvas
• Build campaigns across multiple channels, including Native, Display, Video, Connected TV, Audio, and social platforms like Facebook and Instagram
• Seamlessly sync first-party audiences with open web campaigns by connecting directly to email platforms
• Set alternative paths for unique audience segments
• Visualize and manage campaigns in real-time

How you will make an impact

• Be a key contributor. You will drive critical projects that deliver real value to our customers, contributing to platform and feature development on a large, distributed system that handles 1.5 million requests per second with 120ms response times. You will design and improve key components, focusing on performance and scalability, while monitoring code to ensure it meets user needs and business goals. You will tackle the most challenging production issues while being a role model for less experienced developers on the team.
• Guide technical decisions. You will lead decisions that shape the backend tech stack. You will work closely with stakeholders and senior engineers to solve technical challenges and optimize system performance. You will take ownership of projects, from planning to delivery, ensuring solutions address technical and business needs while tackling technical debt.
• Enhance Agile processes. You will participate actively in Agile Scrumban practices, breaking down tasks and collaborating in daily stand-ups. You will help the team navigate challenges, size efforts, identify improvements, and share insights that enhance project delivery from start to finish.
• Prioritize quality. You will participate in code reviews, analysis, and performance tuning. You will apply various automated testing methods in a continuous integration environment, resolving defects and bugs during pre-production, production, and post-release patches. You will directly influence the outcome quality by identifying process and behavioral gaps, suggesting and driving improvements to avoid, mitigate, or delegate risks.
• Mentor and grow the team. You will work with urgency, embrace mistakes, learn from them, and drive the team toward success. As a senior team member, you will offer guidance and coaching to junior developers and contribute to the team’s success at every opportunity. With time, you will also take part in the recruitment process of other engineers.

What you bring

• Technical expertise. You bring experience with Java and Spring, and have a deep understanding of building highly available, high-performance systems. You are skilled in optimizing web application performance across the stack, with hands-on experience in Kubernetes, Docker, and Microservices. You are comfortable working with relational databases and key-value stores, proficient in SQL, database schema design, and infrastructure, and familiar with NoSQL databases. Your expertise also extends to Unix/Linux environments, design patterns, and functional programming, with a working knowledge of networking, concurrency, and Big Data concepts (e.g., Hadoop, HDFS, or Druid).
• Experience. You are passionate about building technical solutions and thrive on simplifying complex challenges. You have worked closely with Product and Design teams to design, implement, and iterate on impactful end-to-end product experiences.
• Interpersonal skills. You take a collaborative approach and lead by example. You can translate complex technical details to non-technical audiences and build trusting relationships across teams, whether in-person or remotely. You adapt quickly when priorities shift, embrace feedback, and are comfortable navigating ambiguity. You value diverse experiences and perspectives.
• Growth mindset. You are naturally curious, eager to learn from others as well as independently. You acknowledge mistakes, learn from setbacks, and are resourceful in applying new knowledge to solve problems. You stay current with the latest tools and best practices, driven by a passion for continuous improvement.
• Language skills. English and Ukrainian languages at Upper Intermediate level or higher.

Brainence is looking for a Kotlin/Java Engineer! You’ll shape key technical decisions, refine the API stack, and mentor the team – all while building a top-tier journey-based ad platform. Bring 4+ years of Kotlin/Java, plus Spring Boot, Kubernetes, Docker, and Microservices experience.

About the project

illumin is a unique journey-based advertising platform that combines media planning and buying in an interactive and intuitive interface. It allows users to:

• Drag and drop audiences, creatives, and conditions onto a single-screen canvas
• Build campaigns across multiple channels, including Native, Display, Video, Connected TV, Audio, and social platforms like Facebook and Instagram
• Seamlessly sync first-party audiences with open web campaigns by connecting directly to email platforms
• Set alternative paths for unique audience segments
• Visualize and manage campaigns in real-time

Responsibilities

• Play a critical role in advising on technical decisions that will impact the entire API stack at illumin
• Сommunicate complex technical ideas both verbally and in technical design documents
• Collaborate with stakeholders and other senior engineers to identify and solve technical challenges
• Advise teams on consolidating technical debt while addressing business needs
• Mentor the team, uphold software development best practices, and conduct thorough code and technical spec reviews
• Contribute significantly to key projects that deliver value to customers

Requirements

• 4+ years of experience with Kotlin, Java, and frameworks like Spring and Spring Boot
• Experience with Swagger, Kubernetes, Docker, and microservices architecture
• Strong understanding of API design principles, distributed systems, and working with both relational and key-value data stores
• Demonstrated ability in logical thinking and problem-solving in technical and architectural contexts
• A strong desire to simplify complex processes
• English and Ukrainian languages at Upper Intermediate level or higher

We are looking for a skilled Senior Backend Developer (Golang, Typescript) to build and support high-performance backend services for a FinTech platform. The ideal candidate should have strong experience with TypeScript and Go (Golang), and a solid background in designing scalable, secure solutions within a cloud-native architecture.

Requirements

• Fluent in English with excellent communication skills.
• 6+ years of experience in developing and maintaining backend services using TypeScript and Go (Golang).
• Strong expertise in GraphQL (Apollo Server) and RESTful API development.
• Solid understanding of cloud-native architectures, particularly AWS serverless solutions (Lambda, API Gateway, DynamoDB, CloudFormation).
• Experience with NoSQL and SQL databases, with an emphasis on performance optimization.
• Strong knowledge of authentication, authorization, and security best practices.
• Exposure to DevOps practices, CI/CD pipelines, and infrastructure as code.
• Frontend experience is a plus: React, CSS, Next.js.
• Strong problem-solving skills and ability to work in a fast-paced environment.

Would be a plus

• Experience working in FinTech or other highly regulated industries.
• Knowledge of blockchain technologies and cryptographic security.
• Understanding of financial data processing, payment gateways, and transaction security.

Responsibilities

• Develop and maintain backend services using TypeScript and Go (Golang).
• Build and optimize GraphQL APIs with Apollo Server and REST APIs using Koa.js (or equivalent in Go).
• Integrate with third-party APIs and external services.
• Design and manage AWS serverless architectures including Lambda, API Gateway, DynamoDB.
• Ensure security, authentication, and data protection using JWT, OAuth.
• Optimize API performance, caching strategies (Redis), and database queries.
• Implement CI/CD pipelines and Infrastructure as Code (IaC) using CloudFormation.
• Handle error logging and monitoring using AWS CloudWatch.
• Optimize database queries and indexing for high-volume transaction processing.
• Write and maintain unit, integration, and end-to-end tests using Jest (or relevant testing frameworks in Go).
• Collaborate with frontend teams, product managers, and designers to ensure seamless integration.
• Mentor junior developers and review code for best practices.
• Maintain API documentation and system architecture.
• Adhere to industry standards for FinTech and implement best practices.

On behalf of our Client from the UK, Mobilunity is looking for a Lead WordPress developer.
Our client is a digital product, customer experience, and engineering agency specializing in creating impactful digital solutions for businesses. They offer a full range of services, including digital strategy, UX/UI design, brand development, backend and frontend engineering, CMS and API integration, SEO and PPC optimization, as well as print media design and ongoing support. Their expertise spans from eCommerce development to A/B testing and service design, ensuring seamless and effective customer experiences.
They are looking for an experienced Lead WordPress Developer to take ownership of their development projects from start to finish. This role requires a well-rounded professional who can build and maintain WordPress websites, manage small-scale support tasks, and occasionally interact with clients. The ideal candidate should be comfortable balancing development work with light project management responsibilities.

Responsibilities:

• Develop, maintain, and optimize WordPress websites, including custom themes and plugins.
• Handle support requests via a ticketing system, troubleshooting issues related to websites, hosting, emails, and DNS when needed.
• Work closely with the technical director to deliver projects and improve workflow efficiency.
• Engage in client interactions, including video calls, to discuss technical aspects of projects when required.
• Collaborate with potential outsourced developers and oversee small-scale project management tasks.
• Maintain version control using Git and follow best coding practices.

Requirements:

• Strong experience in WordPress development, including custom themes, plugins, and troubleshooting.
• Experience working with hosting environments, DNS, and email configurations.
• Knowledge of version control systems (Git) and deployment best practices.
• Excellent time management skills, with the ability to balance large-scale projects and daily support tasks.
• Strong communication skills with the ability to interact with clients professionally.
• Ability to work independently and take ownership of projects while collaborating with the team.
• Experience with ClickUp or similar project management tools is a plus but not required.
• Level of English – Upper-Intermediate and higher

Preferred qualifications:

• Experience in leading development projects and mentoring junior developers.
• Some exposure to project management, including task prioritization and delegation.
• Familiarity with QA processes to ensure high-quality deliverables.

On behalf of our Client, a well-established financial institution from the Caribbean region Mobilunity is looking for a Java Developer.
Our Client is the largest bank in the Caribbean region that serves 14 countries/territories. The aim is to make this organization from a traditional bank into a new era of fintech, working on the edge of what current fintech may offer.

Responsibilities:

• Develop and maintain scalable and efficient backend services.
• Write clean, maintainable, and efficient code, adhering to best practices and coding standards.
• Develop and maintain RESTful APIs for integration with front-end services and external services.
• Integrate third-party services and maintain data integrity.
• Implement unit and integration tests to ensure robustness and reliability of backend services.
• Optimize applications for speed, scalability, and data security

Requirements:

• Proficiency in Java and corresponding frameworks.
• Strong knowledge of database technologies and web server technologies (e.g., Apache, Nginx).
• Familiarity with version control tools such as Git and experience with RESTful API development.
• Excellent problem-solving skills, communication skills, and attention to detail.
• Bachelor’s degree in computer science, Software Engineering, or related field.
• Level of English – Upper-Intermediate and higher.