Kozak Agency

What we're looking for
We’re looking for a Full Stack Engineer who enjoys building real-time, interactive systems that
go beyond traditional web applications.
This is not a typical CRUD-focused role. You’ll be working on a product that combines rendering, input systems, video, and backend services into a single performance-sensitive
experience.

You should be comfortable operating in a fast-moving startup environment where requirements evolve quickly. We value engineers who take ownership, think creatively, and are comfortable
solving problems without fully defined specifications.

Who we are
we are venture-backed startup building patented technology that enables anyone to turn video into interactive games instantly, with no code.
We are creating a new category of interactive gaming content, combining real-time rendering, video, and game mechanics across mobile and web.

What you'll do You’ll work across the full stack, building both frontend interactive systems and backend
services that power them.
You’ll be responsible for optimizing the browser-side rendering and interaction layer, working with the DOM, Canvas 2D, WebGL, and browser APIs, and interfacing with our WebAssembly-based game engine.

On the backend and platform side:
● Design and build scalable Node.js services and APIs
● Model and manage data in MongoDB for real-time and user-generated content systems
● Develop systems that support gameplay state, media, and interactive features
● Ensure reliable communication between frontend systems and backend services
● Contribute to system architecture, performance optimization, and scalability decisions

On the frontend and rendering side:
● Collaborate with cross-platform engineers to integrate our WebAssembly-based game
engine into the browser environment
● Build video playback integrations that synchronize tightly with a real-time game loop
● Implement input handling systems such as touch, pointer events, and device orientation
with low-latency feedback
● Optimizing a high-performance rendering pipeline using Canvas 2D and WebGL to
achieve consistent performance and smooth frame rates on mobile browsers

Across the stack:
● Write unit, integration, and browser-based tests to ensure reliability
● Contribute to technical documentation and internal tooling
● Work closely with product, design, and engineering teams to ship features end-to-end

Core requirements
● Strong experience with Node.js, React, and MongoDB
● Solid JavaScript or TypeScript fundamentals
● Understanding of browser performance, including render loops, repaint behavior,
memory usage, and input latency

Nice to have
● Experience with Kotlin Multiplatform and WebAssembly
● Experience with Canvas 2D and WebGL in production or advanced projects
● Experience with game development or real-time interactive systems
● Experience with graphics, animation systems, or media-heavy applications
 

A Senior Java Backend Developer is required to work on a large-scale video streaming platform with DRM, OTT services, and distributed architecture.

The role is focused on backend development, system design, and building reliable, high-load services.

What the role involves
Backend services are designed and developed as the core of the platform, handling users, content, security, and communication between multiple systems

The work directly impacts how video content is securely delivered to users across web, mobile, and TV devices.

Main responsibilities
Design and development of backend services using Java (primary language)
Development and support of REST APIs and microservices
Implementation of authentication, authorization, and access control logic
Work with high-load systems and distributed architecture
Design and optimization of database structures and data replication
Integration with DRM systems and content protection services
Implementation of content lifecycle logic (VOD, live streams, catch-up, user rights)
Ensuring scalability, fault tolerance, and performance
Implementation of monitoring, logging, and system health checks
Collaboration with frontend and infrastructure teams
Tech stack (focus)
Java (Spring / Spring Boot preferred)
REST APIs, microservices
SQL / NoSQL databases
Distributed systems and data replication
Linux-based environments

Nice to have (big advantage)
Experience with video streaming platforms (OTT, IPTV)
Knowledge of DRM technologies (Widevine, PlayReady, FairPlay)
Understanding of HLS / MPEG-DASH streaming
Experience with CDN / media delivery systems
Kotlin experience (optional)
What makes the role interesting
Work on a complex, real-world high-load system
Solving scaling and performance challenges
Building systems combining backend, security, and media streaming
Opportunity to contribute to architecture-level decisions

Candidate profile
Strong experience in Java backend development
Good understanding of system design and microservices
Experience with high-load or distributed systems
Ability to work with complex technical domains
Focus on clean, maintainable, and scalable code
Additional requirements
English proficiency at B2 level or higher (written and spoken)

FTE: Full time (40 h per week)
Timeline: 3-6 months (tbd)
Start: ASAP
English: B2
Recruitment process: a tech check with us, then an interview with the client

Requirements:
A Full-Stack Craftsman: You are an expert in Ruby on Rails and TypeScript, capable of building everything from complex dashboards and billing UIs to sleek documentation platforms.

The "DevEx" Champion: You have a natural empathy for other developers. You’ll develop deep knowledge of our platform (Pub/Sub, Chat, LiveSync) and use the product yourself to gain a first-hand understanding of the developer experience.

Comfortable with Ambiguity: You thrive in high-level vagueness. You can take a feature from a loose concept to a shipped product with minimal hand-holding, identifying problems and proposing solutions independently rather than waiting for a roadmap.

Accountable & Reliable: You take pride in high-quality, well-tested code. You meet your delivery commitments, provide realistic estimates based on technical complexity, and communicate proactively if a timeline is ever at risk.

An Owner: You monitor what you build in production and take personal ownership of quality issues. You see a feature through its entire lifecycle, from the first line of code to the final metric.

English: Intermediate+

Requirements:

• 4+ years in backend/fullstack development
• Strong experience with Node.js + TypeScript (NestJS preferred)
• Solid experience with PostgreSQL and relational DB design
• Experience building scalable REST APIs
• Experience with Redis (caching, queues)
• Experience with React / Next.js for admin panels / CMS
• Experience with role-based access control and permissions
• Experience with media/content platforms is a plus
• Experience with AWS or similar cloud (S3, CDN, compute)
• Understanding of video/audio streaming integrations (HLS, RTMP) is a plus
• Experience with analytics, subscriptions, and content gating logic is a plus

Project context:
* Building a streaming platform (audio + video + live + podcasts)
* Mobile apps (Flutter) + Web CMS
* Custom backend required (API + admin panel)
* Client provides hosting & streaming infra
* Need scalable architecture and clean implementation

Main responsibilities:
* Design and implement backend architecture (NestJS)
* Build REST API for mobile apps and CMS
* Design PostgreSQL schema
* Implement CMS (React / Next.js)
* Integrate streaming layer (as orchestration, not from scratch)
* Implement subscriptions, content gating, analytics
* Collaborate with mobile team

Work likely through UpWork !!!

Senior DevOps / MLOps Engineer to support an early-stage startup building a machine learning platform on Google Cloud.

Location: any
Start: ASAP
Duration: mid-long term
Engagement:  Part-time
English: B2+

We are looking for a Senior DevOps / MLOps Engineer to support an early-stage startup building a machine learning platform on Google Cloud.

The role focuses on designing and maintaining cloud infrastructure and deployment pipelines for ML workloads, with a strong emphasis on Kubernetes (GKE) and Infrastructure as Code (OpenTofu/Terraform).

Required Experience

• 5+ years in DevOps / Platform Engineering
• Strong hands-on experience with:
  • GCP (production environments)
  • Kubernetes (preferably Google Kubernetes Engine)
  • Infrastructure as Code (Terraform or OpenTofu)
• Experience deploying and operating ML workloads in production
  • model inference (required)
  • training pipelines (basic familiarity expected)
• CI/CD experience (e.g. GitHub Actions)
• Strong understanding of:
  • containerization (Docker)
  • networking (VPC, IAM)
  • environment isolation (dev / staging / prod)

Nice to Have

• Experience with Vertex AI or similar ML platforms
• Experience with ML orchestration tools (Kubeflow, Airflow, etc.)
• Hands-on experience with GPU workloads on Kubernetes
• Familiarity with model lifecycle (versioning, artifacts, deployment)
• Experience in early-stage or fast-moving startup environments

Not a Fit If

• DevOps background without experience supporting ML workloads in production environments
• Experience limited to managed/serverless platforms without Kubernetes
• No hands-on experience with Infrastructure as Code

We are looking for a strong senior C++ / systems engineer for a difficult refactoring project in a production real-time AI vision system.
Current stack / context includes:
* modern C++
* real-time video / panorama processing
* computer vision / detections
* GPU-related components such as CUDA / TensorRT
* renderer / geometry / camera-behavior related logic
* legacy code that needs structured refactoring, not a rewrite

We already have internal AI / model / post-processing ownership. What we are missing is strong C++ / systems / architecture support.

We are looking for someone with:
* very strong C++
* experience refactoring legacy production systems
* real-time / low-latency systems thinking
* strong ownership / data flow / architectural judgment
* ideally some exposure to CUDA, TensorRT, OpenCV, video or rendering-related systems

Project Overview
The project focuses on building a production-ready enterprise AI chatbot on SAP BTP Kyma, leveraging modern AI and backend technologies such as SAP Joule, Node.js/TypeScript, NestJS, mastra AI, OpenSearch, and SAP HANA.

The platform emphasizes AI architecture, reliability, and scalability, enabling advanced RAG pipelines, agent-based capabilities, and secure enterprise integrations. Strong engineering practices, observability, and AI quality evaluation are key success factors.


Role Responsibilities
As an AI Developer, the consultant will:

• Design and implement agentic AI capabilities, including tool/function calling, planning, memory/state handling, safety guardrails, and failure recovery
• Build and optimize advanced RAG pipelines on OpenSearch (hybrid retrieval, embeddings, rerankers, query rewriting, retrieval evaluation)
• Develop and maintain API and MCP integrations, including MCP servers/clients, capability manifests, and clean, versioned REST/WebSocket APIs
• Create and iterate prompt strategies, including tool-aware prompting, structured outputs (JSON), and prompt governance
• Establish AI quality evaluation and testing, using tools such as RAGAS and/or DeepEval, including regression testing and red-teaming
• Implement secure and performant data access with SAP HANA using TypeORM
• Ensure observability and performance monitoring using Dynatrace (latency, cost, quality, SLIs/SLOs)
• Build and maintain CI/CD pipelines for Kyma/Kubernetes environments

Collaborate closely with product and architecture teams, document designs, and participate in technical reviews

Mandatory Skills and Experience — MUST HAVE !!!

• Proven production AI adoption, including agentic or advanced RAG solutions with measurable impact
• Strong experience with advanced RAG on OpenSearch (vector and hybrid search, indexing strategies, retrieval evaluation)
• Experience with agent frameworks and patterns (multi-step planning, tool integration, memory/state, guardrails)
• Hands-on experience with AI evaluation and testing (RAGAS, DeepEval, or similar)
• Strong Node.js and TypeScript skills; solid API engineering (REST/WebSockets, OpenAPI, versioning)
• NestJS experience in enterprise-grade services
• Experience with MCP integrations in production or strong evidence of rapid ramp-up capability
• Strong experience with SAP HANA and TypeORM
• CI/CD experience for containerized applications on Kyma/Kubernetes
• Dynatrace experience for observability and performance monitoring
• Security-first mindset (OAuth2/OIDC, JWT, RBAC, secure secrets handling)
• Ability to learn quickly and work within complex enterprise architectures
• Fluent English
  
  
  Nice to Have
• SAP ecosystem knowledge; SAP Joule experience is a plus
• Experience with mastra AI or similar AI orchestration frameworks
• Advanced prompt engineering skills and prompt governance workflows
• Experience integrating AI into web frontends (streaming responses, SSE, rate/cost controls)
• Experience with multiple LLM providers and routing strategies
• Knowledge of data privacy and compliance (e.g. GDPR-aware AI design)

Project Details
Start: ASAP
Duration: Until 31.10.2026 (extensions possible)
Estimated Effort: 960 hours
Location: Fully remote
Language: English
Candidate Location: EU

We have received an initial inquiry regarding Elixir developers. At this stage, there are no specific project details — the request is exploratory, aiming to understand whether we have suitable candidates available.
 

We are looking to identify:

Elixir developers (mid-level and senior)
Availability for both full-time and part-time engagement

Please share any relevant candidates along with:

CV/resume
Current availability (including notice period, if applicable)
Preferred engagement type (full-time or part-time)

We are looking for an Senior Android Platform / C++ Engineer (AOSP) to join a project related to the virtualization of Android phones and using RDP (Remote Desktop Protocol) on Android smartphones.

Requirements:
- Solid experience with Android platform development (AOSP)
- Good knowledge of C/C++ and system-level programming
- Strong understanding of Android architecture (framework, services, user space)
- Experience with inter-process communication (Binder, sockets, shared memory)
- Hands-on experience modifying init.rc, sepolicy, system services
- Experience with debugging tools (logcat, strace, gdb, perf, etc.)
- Familiarity with Linux environment and fundamentals

Nice to Have
- Experience with HAL / HIDL / AIDL / JNI
- Knowledge of Android networking stack, Wi-Fi, GPS
- Familiarity with Linux kernel internals
- Experience in reverse engineering
- Solid experience with Android platform development (AOSP)
- Good knowledge of C/C++ and system-level programming
- Strong understanding of Android architecture (framework, services, user space)
- Experience with inter-process communication (Binder, sockets, shared memory)
- Hands-on experience modifying init.rc, sepolicy, system services
- Experience with debugging tools (logcat, strace, gdb, perf, etc.)
- Familiarity with Linux environment and fundamentals

Requirements:
• Strong experience in data modeling (logical & physical) with scalable design
• Hands-on experience with Snowflake and dbt
• Familiarity with AWS data services in a cloud environment
• Experience working with HR data and/or Workday structures
• Understanding of semantic layers and data governance practices
• Ability to translate business needs into structured data models
• Strong knowledge of data quality, validation, and compliance

Nice to have:
• Experience with Workday API integrations
• Background in HR data transformation projects
• Exposure to AI-driven data solutions or automation workflows
• Experience collaborating with cross-functional teams (Data / AI / HR)

• Location: Remote (with 4h overlap with New York)
• Duration: 3–6 months

Searching for an Ember Developer with experience in JavaScript (ES6+), TypeScript, HTML5, and CSS3.

English: B2
Location: Ukraine & Europe

We offer:

• Cooperation with a stable company with well-established processes and a positive atmosphere
• Experience in project management of different levels of complexity, methodology, and approaches
• Flexible schedule: Mon-Fri (8 hours a day)
• 18 days of paid vacation; 15 days sick leave
• A decent level of remuneration with regular reviews of the results of cooperation
• Extensive loyalty program 

Requirements:

• 7 years total
• 3+ yrs - Next.js
• 5+ yrs - Node.js (Nest), Typescript
• 1+ year of experience with AI domain
• Experience with Clickhouse preferable

An AI platform for YouTube creators that analyzes channels and competitors, searches for viral ideas, generates video scripts and engaging thumbnails, prepares SEO-optimized titles and descriptions, analyzes retention and CTR, provides detailed channel analytics, offers AI agents for content creation, includes a Telegram bot and web app for management, and facilitates content planning.

Core responsibilities:

• Support and development of the ClickHouse scraping pipeline,
• Monitoring core platform logs,
• Improving the current architecture,
• Developing new features.

Work directly with CEO and CTO with no project managers, well defined tasks - tasks are set in chat Strong ownership; knowledge of architecture patterns.

This is a hands-on engineering role focused on building a fast, reliable, and user-friendly interface for DeFi workflows. You will work closely with backend engineers and product stakeholders to deliver production-ready features for real users.

Responsibilities:
Frontend Development

• Own and maintain the frontend application built with Next.js, React, and TypeScript
• Build scalable and high-performance interfaces for DeFi workflows, dashboards, and portfolio views
• Implement wallet connectivity and transaction flows
• Maintain strong standards for code quality, performance, testing, and maintainability

Web3 & Data Integration

• Translate complex on-chain data into clear user-facing product experiences
• Integrate blockchain data from RPC endpoints, event logs, indexed sources, and subgraphs
• Work with DeFi protocols and yield-related products
• Ensure correct handling of token decimals, pricing logic, balances, APY calculations, and other financial data

Product Development

• Build features such as portfolio tracking, transaction history, yield opportunities, delegation flows, and dashboard analytics
• Collaborate on product decisions and help shape intuitive UX for complex blockchain functionality
• Improve real-time data handling and frontend performance

Collaboration

• Work closely with backend engineers on APIs, data models, and system design
• Participate in code reviews, technical discussions, and architecture decisions
• Contribute to scalability and long-term engineering standards

Tech Stack

• Frontend: Next.js, React, TypeScript
• Blockchain: Viem, Ethers, smart wallet integrations
• Database: PostgreSQL, Prisma
• UI / Styling: Tailwind CSS, charting libraries
• Data Fetching: SWR
• Infrastructure: GitHub Actions, Docker, cloud hosting
• Blockchain Scope: EVM-compatible chains
• Protocol Integrations: Lending, swapping, yield, and routing protocols

Requirements

• 4+ years of experience building Web3 or crypto-native products
• Strong experience shipping production applications used by real users
• Strong proficiency in TypeScript, React, and Next.js
• Experience working with on-chain data, including RPC, logs, subgraphs, and multicall
• Strong understanding of wallet integrations, transaction lifecycle, gas mechanics, and token standards
• Familiarity with DeFi primitives such as lending, liquidity pools, swaps, vaults, and yield strategies
• Ability to turn complex blockchain data into intuitive product experiences
• Strong ownership mindset and ability to work independently in a fast-moving environment

Nice to Have

• Experience working at a DeFi, crypto infrastructure, analytics, or exchange product
• Familiarity with smart wallet infrastructure
• Experience with typed signing standards such as EIP-712
• Experience building financial dashboards or real-time data-heavy applications
• Contributions to Web3 open-source projects

What Success Looks Like

• A stable and high-quality frontend application that makes complex DeFi workflows easy to use
• Accurate and reliable presentation of on-chain portfolio and yield data
• Smooth wallet and transaction UX across multiple EVM chains
• Strong collaboration with backend and product stakeholders to deliver production-ready features quickly

Requirements:
• 6+ years of software development experience, including 5+ years in AI/ML or LLM-focused roles
• Strong Python skills
• Hands-on experience with LibreChat (deployment, customization, integrations) !!!
• Experience with LLMs (OpenAI, Google Gemini, etc.)
• Strong knowledge of RAG architecture, prompt engineering, and agent workflows
• Experience with LangChain, LlamaIndex or similar frameworks
• Experience with Vector DB (pgvector/PostgreSQL) and MongoDB
• Experience with Docker, Kubernetes (GKE), CI/CD
• Experience with Microsoft 365 integrations (Teams, Outlook, SharePoint, Graph API)
• Strong system design and architecture skills
• Good communication skills