Jobs Backend

Key responsibilities:
 

• Design and develop backend services and internal systems.
• Integrate with external services and APIs.
• Contribute to the architecture of new products and services.
• Analyze business requirements and translate them into technical solutions.
• Break down tasks, estimate complexity, and plan implementation.
• Work with databases and optimize their performance.
• Develop and maintain REST APIs.

Requirements:

• Strong proficiency in Python.
• Experience designing and developing services and distributed systems.
• Understanding of HTTP, REST APIs, and client-server architecture principles.
• Basic understanding of computer networks and networking protocols.
• Experience integrating with third-party services and APIs.
• Experience working with Docker.
• Proficiency with Git.
• Ability to independently define technical solutions, decompose requirements, and build implementation plans.
• Strong systems thinking and solid engineering practices.

We offer:

• Opportunity to work on cutting-edge defense technologies with real-world impact.
• Professional growth opportunities in a rapidly expanding international company.
• A chance to contribute to products used in mission-critical environments.
• Collaborative team of highly skilled engineers and innovators.
• Flexible and dynamic working environment.
• Competitive compensation package evaluated on a individual basis
• Medical insurance after the probation period.

About Flamingo

Flamingo is revolutionizing the Managed Service Provider (MSP) industry with an AI-driven, open-source platform for IT and security. Our goal is to empower MSPs with automation, optimization, and scalability tools to enhance their operations. 

Role Overview

As a Senior Back-end Engineer (Java) at Flamingo, you will design and develop scalable, high-performance back-end services and APIs using Java and Spring Boot. You will be responsible for implementing event-driven microservices, optimizing system performance, and ensuring high availability as we scale our platform. Your expertise in processing high-volume logs and integrating multiple data sources will be critical to building a robust and efficient system.

Key Responsibilities

• Design and develop scalable backend services and APIs using Java (Spring Boot).
• Architect and implement event-driven microservices with Kafka and RabbitMQ.
• Process and analyze high-volume logs efficiently to ensure scalability and real-time insights.
• Integrate and manage multiple data sources, including SQL, NoSQL, and streaming data.
• Optimize database performance using PostgreSQL, Redis, and Elasticsearch.
• Implement authentication and authorization mechanisms with OAuth, JWT, and Keycloak.
• Collaborate with front-end and DevOps teams to build a seamless and resilient system.
• Ensure code quality through automated testing, CI/CD pipelines, and best engineering practices.

Qualifications

Must-Have:

• 5+ years of experience in backend development with Java and Spring Boot.
• Experience in microservices architecture, including event-driven systems (Kafka, RabbitMQ).
• Strong knowledge of RESTful APIs, GraphQL, and WebSockets.
• Experience processing high-volume logs and working with log management tools (ELK stack, Loki, Fluentd, OpenTelemetry).
• Experience working with multiple data sources, including relational (PostgreSQL) and non-relational (Redis, Elasticsearch) databases
• Experience with containerization (Docker, Kubernetes) and cloud platforms (AWS/GCP).
• Understanding of security best practices in backend development.

Nice-to-Have:

• Experience with functional programming in Java or Scala.
• Familiarity with distributed tracing (e.g., Jaeger, Zipkin) for microservices.
• Knowledge of cloud-native architectures and serverless frameworks.
• Exposure to message queues and event sourcing.

Why Join Flamingo?

• High-impact role: As a back-end engineer, your contributions will directly shape Flamingo’s product and technology.
• Innovative Tech Stack: Work with cutting-edge open-source technologies in AI, automation, and security.
• Remote-first Culture: Flexibility to work from anywhere while collaborating with a top-tier team.
• Mission-Driven Company: Join a team passionate about disrupting the MSP industry and making enterprise-grade security and IT automation accessible to all.

Our client is the leader in the Early Childhood Education (ECE) sector, providing the most widely used developmental assessment and curriculum system in the US. They are looking for a talented, innovative, and experienced Senior Backend (Go) Software Engineer to join their established product team responsible for building and enhancing key platform capabilities, working on software that supports millions of daily users.

Their Software Engineering team is responsible for building SaaS solutions used by educational organizations across the globe. The team works on a wide variety of projects, solving existing problems while enabling new business objectives. They believe that great technology experts are also software generalists who are unafraid to jump up and down the stack to solve the challenges that come their way. If you enjoy working in a collaborative, fast-paced environment, are curious about how products work, and love building scalable software, this opportunity is for you.

As a Senior Backend (Go) Software Engineer, you will:

• Develop new features, components, and modules to support organizational growth;
• Build and maintain robust backend services and APIs powering a high-traffic SaaS platform;
• Participate in planning, analysis, and design of new software solutions;
• Investigate, troubleshoot, and resolve performance bottlenecks across the application;
• Design and build scalable, reliable backend solutions using modern software architecture principles;
• Learn new technologies and stay up to date with both established and emerging best practices;

• Work independently while collaborating closely with cross-functional team members to ensure successful project delivery.

   

Qualifications:

• 8+ years of production experience in software engineering and SaaS product development;
• Senior-level knowledge of Golang;
• Experience designing and building scalable distributed systems;
• Strong understanding of modern software architecture, including SOA and microservices;
• Strong knowledge of relational databases (e.g. PostgreSQL);
• Working knowledge of AWS and familiarity with services such as Kubernetes, Redis, and SQS/SNS;
• Excellent debugging, testing, and problem-solving skills;
• Strong communication and listening skills, with the ability to explain complex technical challenges, perform root cause analysis, and propose effective solutions;
• Curiosity to understand how products work and a genuine interest in technology;
• Experience working in Agile development environments;
• Commitment to security, accessibility, and performance best practices;
• Self-starter with a strong sense of collaboration, teamwork, and accountability;
• Experience using AI developer tools (e.g. Codex);
• Familiarity with LLM/AI APIs and prompt-based workflows;
• Databricks experience is considered a plus, but is not required.

Job Description

• 5+ years of development experience
• .Net Development with WinForm
• Solid understanding of OOP, design patterns, software development principles and best practices
• Experience with Azure Cloud Solutions
• Unit testing
• Good communication and task management skills
• English level - Advanced

Job Responsibilities

• Design, develop, and maintain scalable, API-driven backend services
• Troubleshoot complex technical issues and optimize performance of applications.
• Unit testing
• Collaborate with engineering, product, and design teams to ensure seamless integration across the broader data platform.

Department/Project Description

Client is a leading global Contract Research Organization (CRO) that provides Phase I-IV clinical trial management, market access, and technology solutions with over 30 years of experience.

Ось професійний англомовний переклад вакансії:

About Us

Altum is a Ukrainian IT software development house providing technical expertise to digital agencies and startups across the US and Western Europe. We focus on innovation, scalability, and quality to help businesses grow.

DevOut Labs, part of Altum, is a white-label WordPress development team building high-quality websites for US marketing agencies. Although the hiring process is managed by Altum, this position is open specifically within the DevOut Labs team.

Learn more about us: devoutlabs.com

Job Overview

As a WordPress Developer, you will be responsible for developing, customizing, and maintaining WordPress websites for our clients. You will work closely with design and development teams to create functional, visually appealing web resources that align with client goals. This remote position offers the opportunity to work on engaging projects for a diverse range of clients.

Responsibilities:

• Develop custom WordPress themes and plugins based on client requirements and design specifications.
• Customize existing WordPress themes and plugins to enhance site functionality and user experience (UX).
• Optimize websites for speed, performance, and responsiveness across all devices.
• Collaborate closely with designers and fellow developers to implement designs and website functionality.
• Communicate effectively with project managers and clients to provide status updates and gather feedback.

Requirements:

• Proven experience as a WordPress Developer, backed by a strong portfolio of past projects.
• Proficiency in HTML, CSS, JavaScript, PHP, and MySQL.
• Deep understanding of WordPress architecture, theme creation (theming), and plugin development.
• Experience working with popular WordPress plugins and frameworks.
• Ability to work independently and efficiently in a remote work environment.

Nice to Have:

• Experience with ACF Pro.
• Hands-on experience with Webflow or Shopify.
• Experience with front-end frameworks (e.g., Bootstrap or Foundation).
• Knowledge of basic SEO principles and accessibility standards.
• Experience with other CMS platforms (e.g., Drupal, Joomla) is a plus.

We are looking for a Senior Python/Django Architect to join a long-term project for a Norwegian client in the financial sector.

👥 Team: 10 people — Backend, Frontend, Full-Stack, BA, UX & DevOps

📍 Location: Poland / CET

⏰ Engagement: Full-time, starting in September

✈️ Occasional travel to Norway  may be possible

💼 Project

A specialized cloud-based practice management and workflow platform for accounting firms and financial professionals. The solution centralizes task management, client communication and compliance processes such as AML/KYC.

👤 What we're looking for

A strongly technical Architect who can not only design solutions, but also challenge existing approaches, advise the client, set technical direction and solve complex problems.

🎯 Key requirements:

• Strong expertise in Python & Django (4.2)

• Django REST Framework, Django Filters, Celery

• Django ORM & data modelling

• Strong PostgreSQL & Redis experience

• Proven experience with performance & scalability

• Experience scaling existing Django systems without a "big-bang rewrite"

• Technical & architecture assessments

• Database optimisation

• Experience designing architecture for complex systems

• Good understanding of microservices

• AWS / AWS Fargate

• CI/CD — CircleCI is a plus

• Git / GitHub

• Strong communication with technical & non-technical stakeholders

• Ability to explain architectural decisions, trade-offs and risks

• Client-facing / technical advisory experience

• English C1

🛠 Tech stack:

Python · Django 4.2 · DRF · Django Filters · Celery · PostgreSQL · Redis · AWS Fargate · Angular 21 · TypeScript · RxJS · CircleCI · GitHub

📌 Responsibilities:

• Define and evolve the overall system architecture

• Translate business needs into technical direction

• Drive architectural decisions and technical priorities

• Identify risks and scalability challenges

• Guide engineering teams and provide technical mentorship

• Solve complex technical problems

• Contribute to technical roadmaps

• Work closely with the client and other stakeholders

• Ensure scalability, consistency and quality across the system

Creatio is an AI CRM and workflow platform where people and AI agents work together - with no limits on users, agents, or scale. We help midsize and large organizations run customer workflows in the AI era. With a global team and a large ecosystem of partners, Creatio serves thousands of customers in over 100 countries and automates tens of millions of workflows daily. Genuine care for our clients and partners is at the heart of our DNA.

We’re proud to be recognized by top industry analysts as a Leader and Strong Performer in multiple Gartner and Forrester reports.

In 2025, Creatio was named to Inc.’s Best Workplaces list, recognizing our commitment to employee wellbeing and a strong workplace culture.

Who We’re Looking For

We are looking for an AI Software Engineer to design, build, evaluate, and operate AI-powered capabilities within the Creatio platform.

You will join the AI teams building the agent platform that enables AI agents to safely perform real work in the product: call tools and APIs, read and write data, maintain context, follow permissions, and escalate to humans when needed.

The team also owns the core infrastructure for testing, monitoring, logging, observability, and cost/performance control, ensuring AI agents are reliable, scalable, secure, and production-ready.

This role combines strong software engineering expertise with hands-on AI engineering experience. You will work on enterprise-grade AI solutions, including assistants, copilots, knowledge systems, semantic search, RAG-based capabilities, and agentic workflows.

Responsibilities:

• Design and implement AI-powered product features within the Creatio platform.
• Build assistants, copilots, agentic workflows, knowledge systems, RAG, and semantic search capabilities.
• Integrate LLM providers, tools, enterprise data sources, and MCP-based solutions.
• Develop and maintain backend services using C# and .NET.
• Build evaluation frameworks, quality gates, and observability practices for AI solutions.
• Monitor and improve the quality, latency, cost, reliability, and security of AI capabilities.
• Apply AI coding assistants and engineering agents as part of the daily development workflow.

Requirements:

• Strong experience with C# and .NET.
• Hands-on experience with LLMs, prompt engineering, function calling, and structured outputs.
• Understanding of agent architectures, MCP, RAG, embeddings, vector search, and semantic search.
• Experience with AI evaluation, observability, security, and Responsible AI practices.
• Solid understanding of API design, distributed systems, and software architecture.
• Experience with SQL databases, testing, CI/CD, and cloud-native development.
• DevOps fundamentals, including Docker containerization and basic Kubernetes knowledge.
• Strong knowledge of engineering best practices and production-grade software development.

What to expect from us:

• Growth & Development: Clear career paths, mentorship opportunities, and access to continuous learning to help you reach your full potential.
• Flexibility & Well-Being: We provide flexible work arrangements and initiatives that empower you to manage your schedule effectively, stay productive, and thrive both personally and professionally.
• Recognition & Impact: A culture that celebrates achievements, values your ideas, and empowers you to make real contributions from day one.
• Innovative Culture: Be part of a company that embraces new ideas, modern technologies, and bold thinking to stay ahead of the curve.
• Benefits & Rewards Package: We provide competitive compensation and benefits designed to support you and your family. Our rewards approach goes beyond salary, recognizing your contributions and commitment. The exact package may vary depending on your country of residence and employment type.

Inforce is a Software Development Company that provides a full range of top-quality IT services. Our mission is to develop first-class applications and Websites to provide our clients with the best solutions for maximizing their profits and converting their ideas into reality.

Requirements:

• Knowledge of Golang.
• Understanding of REST APIs and databases.
• Willingness to learn and grow as a developer.
• Good English reading and writing skills (B1 level).
• Ability to work remotely and manage your time.

Responsibilities:

• Learn and write clean, simple Go code.
• Help develop and test backend services.
• Work with databases and APIs.
• Fix bugs and support existing projects.
• Take part in code reviews and daily team meetings.
  
   

We offer:

• Competitive salary
• Interesting and challenging projects
• Future career growth opportunities
• Paid sick leave and working day vacation
• A friendly team of professionals
• The company covers 50% of the cost of courses you need
• Exciting team-building activities and corporate parties

Our Client is a leading VC-backed defense technology company founded to bridge the decades-old gap between modern technology and critical national security requirements.

Today, we are building the necessary infrastructure to bring together sensors, autonomy, and operators with our technologies deployed in active operations around the world.

About this position

We are seeking a Senior Software Engineer to join our Legion Platform team. You will design, build, and deploy high-performance, scalable server systems and integration tools that connect hardware and software systems across environments and levels of command. As part of the Legion team, your expertise will be critical to solving complex system challenges and developing a robust platform that is deployed for real-world military missions. This role requires continuous innovation and is a good fit for an engineer who thrives under pressure and demands that their work have an immediate, tangible impact on national security.

Responsibilities

• Design, develop, and implement high-performance, scalable backend systems that form the foundation of the Legion platform.
• Create and maintain integration tools that ensure reliable connectivity between hardware and software systems at all levels of management and in different environments.
• Apply expertise in the development of distributed systems, data pipelines, and real-time information processing solutions.
• Solve complex system architecture problems to continuously improve and increase the reliability of the platform used for military missions.
• Actively work with relational databases (in particular, PostgreSQL), object storage (e.g., S3, MinIO), and geospatial tools.
• Ensure high engineering standards when developing HTTP APIs (REST, gRPC, or GraphQL) and implement reliable authentication and authorization models.
• Work closely with end customers to gather requirements, develop, and deliver software that has immediate and tangible impact.

Requirements

• 5+ years of hands-on backend engineering experience in fast-paced, production environments using either Go, Python, Rust, C/C++, TypeScript, or similar languages.
• Strong background in APIs, distributed systems, data pipelines, or real-time processing.
• Deep experience with relational databases (e.g., PostgreSQL), object stores (e.g., S3, MinIO), and geospatial tools.
• Strong grasp of HTTP APIs (REST, gRPC or GraphQL) and authentication/authorization models.

Will be a plus

• Experience working with Ukrainian Ministry of Defence, and/or NATO members.
• Exposure to Ukrainian military C2 platforms, including Delta, Kretchet, Oreanda, etc.
• Experience supporting Golang-based applications in production.
• Experience building plugins or integrations for common military command-and-control (C2) platforms (e.g. TAK, Maven, Lattice).

Company offer

• Meaningful stock options
• Full health, dental, and vision coverage
• Relocation assistance
• Unlimited PTO (two-week minimum) and all paid Ukrainian public holidays
• Paid parental leave for both parents

Location Kyiv

Our Client is an engineering-focused startup that combines data analytics with software development. It operates in three main areas: investigative analytics, crypto market research, and cybersecurity. It specializes in developing custom software solutions that handle large-scale data analytics and investigative workflows. Join the team and help build the foundation for a safer digital future

Responsibilities

• Active Technical Leadership (60% Tech / 40% Lead): You will lead by example. You are expected to write high-quality, production-ready Python code while conducting rigorous, constructive code reviews to maintain elite standards.
• System Architecture: You will view every project through an architectural lens, ensuring that our systems are not just functional, but secure, scalable, and resilient.
• Product Ownership & Stakeholder Management: You will wear the PO hat when necessary—translating high-level business requirements into actionable technical tasks, managing the backlog, and ensuring the “why” behind the code is clear to everyone.
• Agile Orchestration: We move fast. You will manage multiple projects simultaneously using Agile methodologies, ensuring the team stays focused, unblocked, and on track across different delivery cycles.
• Cybersecurity Stewardship: Leverage your domain expertise to bake security into the Software Development Life Cycle. You will guide the team in building tools that handle sensitive data, perform complex analysis, and resist exploitation.

Requirements

• 7+ years of experience in back-end or full-stack development with at least 1+ years in a Lead or 2+ Senior role
• One who can translate technical goals into high-quality, scalable, and robust infrastructure.
• Cybersecurity domain knowledge
• Crystal Clear Communication: You are the antidote to “fluff.” You communicate technical complexities in a direct, actionable way to both engineers and non-technical stakeholders.
• Multitasking Prowess: You thrive in a “Startup-Plus” environment. You can switch contexts between three different projects without losing sight of the quality or the deadline.
• Upper-Intermediate English communication skills, both written and verbal (daily communication with clients and team)

Will be a plus

• Familiarity with Crypto/Blockchain
• Experience coordinating with offshore development teams.
• Exposure to large-scale data processing or Big Data technologies.
• Previous experience working with AI-assisted development tools;

Company offer

• Health Insurance
• Professional English Lessons
• Energy Resilience Budget

Location

Kyiv (partially remote)

We are looking for a Middle .NET Developer to join our team and work on an exciting FinTech project. You'll collaborate with experienced engineers to build scalable, secure, and high-performance backend solutions.

Responsibilities:

• Develop and maintain backend services using C# and .NET.
• Design and implement RESTful APIs.
• Participate in architecture discussions and code reviews.
• Collaborate with cross-functional teams to deliver high-quality software.
• Write clean, maintainable, and well-tested code.
   

Requirements:

• 3+ years of commercial experience with C#/.NET.
• Strong knowledge of .NET Core / .NET 6+ and ASP.NET Core.
• Experience with REST APIs.
• Solid understanding of SQL databases (MS SQL Server or PostgreSQL).
• Experience with Entity Framework Core.
• Knowledge of OOP, SOLID principles, and design patterns.

Nice to Have:

• Docker and Kubernetes.
• Azure or AWS.
• Experience with microservices.
• Previous experience in the FinTech domain.

We Offer:

• Remote work and flexible working hours.
• Legal support.
• Paid sick leaves.
• Paid vacations.
• Medical insurance. 
• Free English classes.

ScenAI Data Science Inc

We are a U.S.-based fintech startup operating in the investment and financial services space. Our distributed teams work across Poland, the United States, and Ireland, collaborating on technology-driven solutions related to stocks and investments.

Security, compliance, and the responsible handling of sensitive financial data are central to how we operate, as we build scalable products in a regulated environment.

General

❖ 4–10 years in automation engineering

❖ Strong C# and OOP expertise

❖ Experience with Windows UI Automation (UIA2/UIA3)

❖ Prior hands-on with Silk Test (mandatory)

❖ Experience automating DevExpress WinForms apps

Legacy Experience (Critical)

❖ Experience working on .NET Framework 3.5 / 4.x applications

❖ Automation in thick-client enterprise systems

❖ Handling unstable UI identifiers

❖ Working with limited documentation

Framework & Design

❖ Build frameworks from scratch

❖ Implement POM / Component Object Model

❖ Logging, retry policies, custom wait strategies

Initial contract duration: 9 months with the possibility of extension based on the skill set

Hourly remuneration: 28-35 usd/hour

Engagement: full time

Time zone: Poland

Working language: English

Please read carefully before applying:

The client is building a product in the bank/investment/brokerage systems niche, and their investors have strict security and compliance requirements, where every person will go through a background check.

Why Poland?

For background check — you must be a taxpayer in Poland for 2+ years.

Our startup is growing fast, and we already have real clients using and testing the product. That is why we are looking for a strong Python Backend Developer with practical experience in AI solutions, agents development, vector databases, graph databases who wants to join us at an early stage and become part of building a real technology company.

English B1-B2 is required, as English is the main language of communication within our international team.
You will not be joining the project alone — our development team already includes two Middle Python Developers, one Senior Python Developer, one Frontend Developer. You will work closely with them, share technical decisions, and help us continue building and improving the product together.
 

What We Are Looking For

• Strong practical experience with Python backend development
• Hands-on experience with vector databases
• Experience with graph databases / knowledge graphs
• Practical experience integrating AI / LLM / ML solutions into real products
• Good understanding of backend architecture, APIs, databases, and data processing
• English B1–B2

What We Offer

• Full remote work
• Flexible schedule
• Opportunity to join an active startup at an early stage
• Real influence on product architecture and technical decisions
• Small team without unnecessary bureaucracy
• Direct impact on the future of the company
• Opportunity to receive company equity

Important

We are looking not just for a developer, but for an engineer who has already worked with AI and modern data technologies in practice.

When applying, please include examples of real projects where you worked with Python backend development, AI integrations, vector or graph databases, knowledge graphs, RAG, or other data-intensive systems.

We are especially interested in what you personally built and what technical problems you solved.

Overview: Algoseek is seeking a proactive, technically adept Algorithmic Support Engineer to provide first-line support to our institutional clients for our intraday market data feeds for quantitative and algorithmic trading data systems. This role bridges finance, market data and technology — requiring both hands-on technical troubleshooting and a deep understanding of trading concepts, market data, and systematic strategies.

This position serves as an entry point into Algoseek, offering strong performers a pathway to grow into development, data, or quantitative analysis roles.

Role Details:

• Location: 100% Remote (Global Team)
• Job Type: Full-time
• Compensation: Competitive with bonuses and education/technical allowance

Responsibilities:

• Provide responsive technical and functional support for Algoseek’s market data clients using real-time intraday datasets.
• Diagnose and resolve incidents related to market data feeds, APIs, and algorithmic trading infrastructure.
• Communicate complex issues clearly to both technical and non-technical users.
• Collaborate closely with developers, data engineers, and product leads to escalate and troubleshoot system issues.
• Analyze  reported data anomalies and communicate with client.
• Maintain accurate documentation of support procedures, recurring issues, and resolution steps.
• Identify improvement areas and propose automation or analytics-driven enhancements to support operations.

Essential Requirements:

• Strong grasp of systematic, algorithmic, and quantitative trading workflows (ideally intraday).
• Knowledge of US equities, options, or futures markets OR experience with cryptocurrencies / digital assets trading environments.
• Hands-on technical ability: scripting in Python, familiarity with SQL / data analysis.
• Excellent English communication skills, written and spoken.
• Analytical mindset; strong problem-solving and troubleshooting ability.
• Demonstrated curiosity and motivation to learn — this role suits those aiming to move beyond support into deeper technical or quantitative tracks.

Desirable Requirements:

• Experience supporting trading systems, data platforms, or market data vendors.
• Exposure to FIX protocol, market data APIs, or cloud environments (AWS preferred).
• Bachelor’s degree in Computer Science, Engineering, Finance, or a related field.

Work Hours:

• 100% Remote
• Overlap required with US EST morning hours (typically 9 AM – 2 PM EST)

What Success Looks Like

• Accurately resolves 90% of first-level support tickets without escalation.
• Demonstrates consistent improvement in understanding client trading workflows.
• Proactively proposes or implements process improvements that enhance system reliability and client satisfaction.

Why Join Algoseek?

• Work with a leading provider of high-quality market data and trading solutions.
• Collaborate with world-class engineers, researchers, and financial experts.
• Drive innovation in automated trading systems and distributed market data solutions.
• Be part of a remote-first, globally distributed team with a culture of ownership and excellence.

What We Offer:

• Competitive monthly compensation aligned with experience and responsibilities.
• A 100% remote work setup with flexibility for work-life balance.
• An opportunity to contribute to the growth of an innovative, fast-paced market data company.
• Professional development opportunities to help you grow into higher leadership roles.

If you’re a skilled finance professional ready to take the next step in your career, we’d love to hear from you!

Job Title:

Block-Builder Engineer

Who we are:

Adaptiq is a technology hub specializing in building, scaling, and supporting R&D teams for high-end, fast-growing product companies in a wide range of industries.

About the Product:

An advanced block construction platform operating on the Ethereum mainnet that processes order flow, transaction bundles, and submits finalized blocks through relay networks in real time. It addresses neutral and efficient block building to unlock new decentralized finance capabilities, including intrablock lending and execution extensions. The system handles high-throughput data pipelines and strict latency requirements, backed by comprehensive observability and analytics to drive iterative improvements based on live production metrics. Strong engineers are essential to maintain system health under real-time load, verify data-driven hypotheses, and innovate on core protocol logic.

About the Role:

The Block-Builder Engineer will join an experienced team in Kraków or Warsaw to develop and maintain a next-generation Ethereum block construction system. You will own pipeline components that ingest order flow and transaction bundles, manage relay submission paths, and ensure stable performance under real-time load. Your work will include building and refining observability platforms, conducting controlled A/B experiments, and driving reliability improvements such as panic mitigation and latency regression detection. As you ramp, you will contribute to optimization-driven block building logic, on-chain intrablock lending protocols, and an execution extension, gaining autonomy and deep technical ownership across the core stack.

Key Responsibilities:

- Integrate and process order-flow ingestion, bundle and transaction handling, back-pressure management, and reintegration of data for block inputs.

- Develop and maintain relay submission paths to ensure end-to-end block delivery under production load.

- Build and enhance telemetry and dashboards using Grafana, Prometheus, Loki and SQL to provide trusted observability.

- Diagnose and correct measurement issues—broken counters, misleading dashboards, and erroneous denominators—to maintain metric accuracy.

- Design, execute and analyze controlled A/B experiments in production, reporting findings objectively, including inconclusive results.

- Identify and resolve system panics, dropped messages, and latency regressions, with automated tests to prevent recurrence.

- Optimize data pipelines and processing systems for high-throughput, low-latency performance.

- Contribute to the development of intrablock lending protocols and associated trusted-execution components.

- Collaborate on an execution extension (BEX) and future protocol and exchange-layer enhancements.

Required Competence and Skills:

- 2–4 years of professional software engineering experience shipping and operating production systems.

- Minimum 2 years working on Ethereum or other EVM-compatible blockchains.

- Proficiency in Rust or strong systems experience in Go, C++ or Java with eagerness to adopt Rust.

- Solid understanding of concurrent and real-time code within large, existing codebases.

- Strong SQL skills and practical experience with Python for data analysis and tooling.

- Familiarity with monitoring and analytics tooling and a drive to ensure metric correctness.

- Rigorous engineering habits, including comprehensive testing and clear distinction between verified and assumed behavior.

- Data-driven mindset with a habit of querying logs and databases to validate change impact.

Nice to Have:

- Exposure to Ethereum block-building protocols (PBS/MEV), smart contract interactions, or trading systems.

- Experience with high-throughput data pipelines, time-series databases, or large-scale analytics.

- Familiarity with Ethereum client internals (reth, geth, revm) or deploying services on Kubernetes and Docker.

Why Us:

We provide 20 days of vacation leave per calendar year (plus official national holidays of a country you are based in).

We provide full accounting and legal support in all countries we operate.

We utilize a fully remote work model with a powerful workstation and co-working space in case you need it.

We offer a highly competitive package with yearly performance and compensation reviews.