Jobs at Djinni

OmiSoft is seeking a motivated Junior UI/UX Designer with a genuine passion for design, structured thinking, and a desire to grow within our team!

Requirements:
— 0,5-1+ year of commercial experience in UI/UX Design
— Experience designing websites and landing pages; experience with mobile applications will be a plus
— Solid understanding of user-centered design principles and methodologies
— A current portfolio showcasing strong visual design skills
— Upper-Intermediate level of English (written and spoken)
— Strong communication, collaboration, and problem-solving skills

Nice to have:
— Completed courses in graphic, visual, or UI/UX design
— Experience with AI-driven UX research tools and methodologies
— Experience designing marketing materials and presentations

Responsibilities:
— UI/UX development for web (preferably) and mobile products
— Creating visual materials and design assets to support the sales team (presentations, landing pages, marketing materials)
— Analyzing usability and proposing creative solutions to improve UX
— Present and explain to clients design decisions in English
— Actively participate in multiple projects across the company and voice your ideas on design improvements

Why Join Us:
— Flexible Work Environment: Benefit from remote work options and a work-life balance that suits your lifestyle
— Collaborative Culture: Join a team that values open communication, teamwork, and continuous learning
— Professional Growth: Support your growth with covered professional courses, ongoing learning opportunities, and clear paths for career development
— Technological Expertise: Our technical team is always keeping up with new technologies, so we are open to experiments and new approaches
— Generous Benefits: Take advantage of paid vacation, sick leaves, and holidays to recharge and maintain your well-being
— Global Exposure: Work on exciting projects with an international focus, primarily serving the Western European and USA markets

Recruitment stages: Intro call with Recruiter — Test Task — Technical interview — Job offer

If you are motivated by design, challenges, and real impact on projects, we would be happy to meet you and tell you more about the team!

Project Description:

We are looking for a Senior Java Developer to help design and build a cutting-edge application for investors to create, manage, and share client portfolios, along with executing trades. This role involves working on high-performance, scalable systems that support real-time investment decision-making. You will be responsible for architecting, developing, and optimizing core backend functionalities while collaborating with global teams to deliver a seamless investor experience.

Responsibilities:

- Design, develop, and enhance Java applications for portfolio creation, trade execution, and sharing functionalities.
- Optimize system performance to ensure real-time data processing and seamless user interactions.
- Develop and integrate APIs to connect with market data providers and trading platforms.
- Ensure data consistency and security in multi-threaded environments.
- Translate business requirements into scalable technical solutions.
- Collaborate with global teams to align development with business objectives.
- Support production rollouts and provide ongoing system maintenance.

Mandatory Skills Description:

- 5+ years of Java development experience, with expertise in designing scalable applications.
- At least 3 years expertise in React
- Azure Cloud Services
- Working knowledge of Spring Framework, RESTful APIs, and microservices architecture
- Strong knowledge of multi-threading, concurrency, and high-performance computing.
- Proficiency in object-oriented design, SOLID principles, and functional programming.
- Experience with messaging systems (e.g., Kafka) and data serialization (e.g., AVRO).
- Familiarity with Agile methodologies and CI/CD pipelines.
- Strong analytical skills and the ability to work in a fast-paced financial environment.
- Excellent communication skills, with the ability to explain technical concepts to business stakeholders.

Nice-to-Have Skills Description:

- Experience with low-latency systems and real-time market data processing.
- Knowledge of financial markets and investment products.
- Experience with trading platforms (e.g., Bloomberg, Tradeweb).
- Proficiency in automated testing and CI/CD best practices.
- Exposure to Python or other scripting languages.

We’re on the hunt for a talented and imaginative Senior Copywriter who knows how to turn ideas into compelling words. If you love crafting stories, creating engaging content, and bringing brands to life through language, we’d love to hear from you.

What you’ll do

• Create content for social media (LinkedIn, Instagram, Facebook, Twitter/X, YouTube) with a strong sense of tone and storytelling, and contribute visual ideas for designers
• Craft stories for the Evoplay Media insights section and develop new content formats
• Write website copy for various projects
• Support marketing and product teams with ad-hoc writing tasks
• Participate in creative ideation sessions for campaigns, product launches, and industry events
• Bring new ideas, formats, inspirations, and creative references

Types of content you’ll create

• Social media storytelling
• Product launch narratives
• Industry insight articles
• Campaign copy
• Website storytelling
• Scripts for videos and media content

• Event storytelling and partner communication

   

What we’re looking for

• Excellent written English — fluent, expressive, a feel for how things should sound
• A varied portfolio — multiple tones and formats that show an impressive range
• Love for exploration — you enjoy searching for a perfect form to express your thoughts and vision
• Talent to approach B2B content, making copy sound more human and relatable
• Deep understanding of storytelling
• Think in concepts, not just sentences
• Notice the difference between good writing and memorable writing
• Niche taste for word choices and aesthetics

• Experience in B2B Marketing

   

Would be a plus

• Experience in iGaming
• AI visuals generation skills
• Experience with targeted ads

We are looking for a CRM & Retention Manager to join an iGaming product team.

In this role you will be responsible for building retention strategy, managing player segmentation and launching CRM campaigns to increase LTV and reduce churn.

Responsibilities:
• Own segmentation strategy and the full retention lifecycle
• Build onboarding, upsell, reactivation and churn-prevention journeys
• Design and manage bonus mechanics (reloads, cashback, freespins, missions)
• Execute multi-channel communication: Email, SMS, Push, WhatsApp, onsite pop-ups
• Run A/B tests for content, cadence and bonus strategies
• Analyze retention metrics (LTV, churn, cohort analysis)
• Work closely with Casino Manager, VIP and Marketing teams

Requirements:
• 2+ years of experience in CRM / Retention
• Experience in iGaming or high-risk e-commerce will be a strong advantage
• English level B1+
• Experience with CRM platforms (FastTrack, Optimove, Smartico, Exponea or similar)
• Strong analytical mindset
• Experience working with retention metrics and A/B testing
• Experience running multi-channel CRM campaigns

Nice to have:
• Spanish language
• Previous experience in gambling / iGaming projects

What we offer:
• Remote work format
• Product environment in the iGaming industry
• Experienced international team

We are seeking a Data Scientist with a strong foundation in physics, control theory, and mathematical modeling to join our team working on cutting-edge autonomous systems. The ideal candidate combines analytical rigor with practical experience in modeling, simulation, and algorithm development for autonomous platforms.

Levels: Middle and Senior (responsibilities and scope will be adjusted accordingly).

Key Responsibilities

• Develop and validate mathematical models for autonomous systems and dynamic environments.
• Apply data-driven approaches for system identification, optimization, and predictive control.
• Analyze large datasets from sensors and simulations to extract insights and improve system performance.
• Design and implement algorithms for control, navigation, and decision-making.
• Collaborate with cross-functional teams to integrate models into real-world autonomous platforms.

Required Qualifications

• 3+ years in R&D or applied data science/software development.
• Strong background in mathematical modeling, system identification, and control theory.
• Proficiency in Matlab/Simulink for modeling and simulation.
• Experience in signal processing and data analysis.
• Programming skills in Python and C++.
• Ability to quickly research and apply recent trends in control theory, autonomous systems, and data-driven modeling.
• Relevant work experience or education in STEM field

Nice to Have

• Knowledge of aerodynamics fundamentals.
• Experience with Machine Learning (e.g., reinforcement learning, predictive modeling).
• Familiarity with simulation tools such as Gazebo, AirSim.
• Hands-on experience with SITL/HITL testing.
• Exposure to flight control stacks like PX4, Betaflight, ArduPilot.

About Us:
Difmark is a P2P platform where users can buy or sell digital goods (game keys, gift cards, top-up cards, software), game accounts, currency (MMO), additional services, and other gaming products without additional fees and intermediaries that are usually involved in such transactions.

The Purpose for the Role:
The Quality Assurance Engineer will ensure the delivery of high-quality, reliable software for Difmark's platform.The role involves testing new features, identifying bugs, and ensuring that the platform provides seamless functionality and a superior user experience.

Probation Period:
The probation period is 3 months, during which the candidate's technical skills, adaptability to the team, and contribution to product quality will be assessed.

Key Tasks and Role:

• Develop and execute test plans, test cases to identify software issues.
• Conduct manual testing of web application.
• Work closely with developers, designers, and project manager to understand requirements and identify potential risks.
• Document and track issues using bug tracking tools, ensuring timely resolution.
• Participate in Agile/Scrum meetings to provide QA insights and updates.
• Perform regression testing to ensure platform stability after updates.
• Continuously improve QA processes and contribute to best practices for software quality.

Requirements:

At least 1.5 years of commercial experience as QA for web-based application.
Solid understanding of testing processes, software development life cycle, and bug tracking.
Proficiency with web testing tools: Chrome DevTools, Postman (or similar).
Knowledge of basic client-server architecture and HTTP(S) protocol.
Experience testing responsive interfaces (desktop, mobile, tablet).
Ability to identify UI/UX issues and describe them effectively.
Experience with bug tracking tools like JIRA.
Basic knowledge of HTML, CSS, JavaScript
Experience with databases (basic SQL query execution)

Soft Skills:
Strong attention to detail and analytical thinking.
Excellent communication and collaboration skills.
Ability to work in a fast-paced, dynamic environment.

Nice to Have:
Experience in the e-commerce industry.
Familiarity with continuous integration and deployment (CI/CD) pipelines.
ISTQB certification or equivalent.

Our recruitment process typically follows these stages:

1. Application screening
2. Interview Stages:
   • Prescreening call (30 min)
   • Technical Interview (60 min)
   • Job Offer
3. Referrals: Employment and Background Check

Our Customer:

A global technology company developing real-time video augmentation and rendering infrastructure for broadcast and streaming environments.
 

Responsibilities:

• Design and implement a native video playback extension that augments HLS streams at runtime across platforms such as Android (ExoPlayer), webOS, Roku, and others;
• Build and maintain a cross-platform rendering layer using OpenGL for real-time video frame processing and compositing;
• Integrate GPU-based overlays and visual transformations directly into the playback pipeline with strict frame-accurate synchronization;
• Develop device-aware architecture to handle platform-specific decoding, rendering surfaces, hardware acceleration constraints, and performance tuning;
• Integrate external SDKs and APIs alongside an internal AR/graphics processing pipeline;
• Optimize rendering performance, memory usage, and latency under real-time streaming constraints;
• Collaborate with QA and Product teams to validate rendering accuracy, synchronization precision, and cross-device stability.
   

Required experience and skills:

• Strong experience with Kotlin;
• Strong hands-on experience with OpenGL (mandatory, core skill), including shader programming and GPU pipeline understanding;
• Solid knowledge of real-time rendering concepts (frame buffers, textures, shaders, synchronization, GPU/CPU interaction);
• Experience integrating OpenGL with native video playback surfaces;
• Practical experience with HLS streaming internals and playback customization;
• Strong understanding of video decoding/rendering pipelines and frame timing control;
• Experience with native video players on at least one of the following platforms: Android (ExoPlayer), webOS, RokuTV;
• Experience implementing low-latency video overlays and graphical composition;
• Understanding of hardware acceleration and performance optimization on embedded/TV devices;
• Proven background in full-cycle software engineering (integration, profiling, debugging, optimization);
• English — Upper-Intermediate+.
   

Working conditions

5-day working week, 8-hour working day;

All UA public holidays are days off;

Vacation and sick leave are covered by the company;

Remote work.

Our Customer:

Our client is a fast-growing cybersecurity technology company developing a large-scale platform for simulating cyberattacks and assessing security posture. The product includes complex web interfaces, high-load backend services, and cloud-native components.
 

Your Tasks:

• Design, develop, and maintain advanced frontend features using React and modern JavaScript (ES6+).
• Build complex UI components, interactive dashboards, and scalable, reusable component libraries (including Storybook).
• Own and evolve the frontend architecture, ensuring high performance, maintainability, and a consistent user experience across the platform.
• Optimize rendering behavior and application performance, minimizing unnecessary re-renders and improving perceived UI responsiveness.
• Collaborate closely with product managers, designers, and backend engineers to deliver high-quality features end to end.
• Participate in technical discussions, frontend architecture decisions, and code reviews.
• Integrate frontend applications with backend APIs (Node.js-based services).
• Work with Git-based workflows and CI/CD pipelines to ensure smooth delivery and deployment.
• Ensure clean, testable, and well-documented code following frontend best practices.
   

Required Experience & Skills:

• 5+ years of professional experience in frontend or web development.
• Senior-level expertise in React and the modern frontend ecosystem.
• Excellent command of JavaScript, with a deep understanding of how the language works (execution context, async behavior, data handling).
• Strong experience designing and maintaining reusable UI components and design systems (Storybook or similar).
• Solid understanding of frontend application architecture, state management strategies, and data flow patterns.
• Experience optimizing React applications for performance and scalability.
• Working knowledge of backend integration (REST APIs, Node.js services).
• Experience working with relational and/or NoSQL databases (e.g., PostgreSQL, MongoDB) at an integration level.
• Familiarity with CI/CD pipelines and modern development workflows.
• Strong focus on code quality, testing, and maintainability.
• English — Upper-Intermediate+ (written and spoken).
   

Working conditions

5-day working week, 8-hour working day;

All UA public holidays are days off;

Vacation and sick leave are covered by the company;

Remote work.

We are looking for a motivated Sales Development Representative to join a B2B sales team working with international markets. This is a junior-to-mid level role that offers hands-on experience in global B2B sales, real responsibility, and clear impact on business growth. The position is well suited for early-career professionals with a strong interest in sales, startups, and business development.

Who This Role Is For

• 2+ years of experience as an SDR or BDR in a B2B sales environment
• Strong interest in sales, business, and startup ecosystems
• Native or near-native English proficiency (written and spoken)
• Ability to create clear, persuasive outbound messages
• Highly organized, self-motivated, and comfortable working with KPIs
• Strong communication and stakeholder management skills

Role Details

• Full-time position
• Fast-paced startup-style environment with ownership and accountability
• Direct exposure to international customers and global markets

Nice to Have

• Experience selling B2B SaaS or technology products
• Familiarity with CRM systems and outbound sales tools
• Educational background in Business, Economics, or a related field

📍 Location: Remote

🕐 Schedule: Full-time, Sunday to Thursday

🌍 Company: A fast-growing affiliate marketing network connecting advertisers with high-quality leads

We’re looking for a detail-oriented and reliable Billing and Payment Collection Specialist to join our finance team. This is a great opportunity for someone who wants to grow in a remote-friendly, performance-driven environment.

🔧 Responsibilities:

• Assist in managing billing operations, ensuring accurate billing calculations and on-time payments from affiliates and advertisers;
• Maintain and update billing records using Google Sheets;
• Coordinate with advertiser managers and finance teams to capture all costs and revenues accurately;
• Work closely with the sales and finance teams to ensure accurate cost and revenue tracking;
• Handle client billing inquiries (affiliates and advertisers);
• Support in preparing financial reports and analysis;
• Contribute to improving billing workflows and overall team efficiency.

✅ Requirements:

• Experience in finance, billing, accounting, or related roles;
• Strong knowledge of Google Sheets;
• Excellent attention to detail and organization;
• English level: B1 or higher;
• Self-starter with the ability to stay organized and deliver results remotely.

We are looking for PHP (Laravel) developers to join a team working on the maintenance and modernization of an existing care-management platform.

The current system is built with PHP, and the next phase focuses on modernizing the architecture and gradually migrating the platform to Laravel.

The team will work on both maintaining the existing solution and actively contributing to the redevelopment effort.

Responsibilities

• Maintain and enhance the existing PHP-based platform
• Participate in the architectural redesign and migration to Laravel
• Implement new features and improve system stability
• Refactor legacy code and contribute to modernization initiatives
• Collaborate with the internal team (Project Manager and Architect)
• Communicate with stakeholders in English

Requirements

• Strong experience with PHP
• Solid knowledge of Laravel
• Experience with maintenance, refactoring, or modernization of existing systems
• Ability to work effectively in a distributed team
• English B2+ for daily communication

Our team provides quality assurance for mobile games developed by the company. We work closely with game designers, developers, and product stakeholders to ensure high quality, stability, and an engaging player experience across different mobile devices and operating system versions.

We continuously improve our QA processes step by step, focusing on efficient testing practices and product quality.

We are looking for a strong junior Manual QA team member who can perform manual testing of mobile games across different devices and operating system versions.

We work remotely, with formal meetings kept to a minimum — one weekly stand-up, and the rest scheduled based on work needs.

Our focus is on maintaining a balance between game quality and business goals to ensure long-term project sustainability and a positive team atmosphere.

We strive to deliver games that we can truly be proud of :)

Requirements

• 1+ year of experience in Manual QA (experience in iGaming / slot games will be a strong advantage);
• Technical education background (required);
• Experience testing mobile applications or games (real devices/emulators);
• Understanding of slot game mechanics (reels, paylines, bonus features, payouts) or experience testing casino products;
• Good analytical and debugging skills, ability to investigate and clearly describe issues;
• Familiarity with Agile development processes;
• Experience working with Jira, TestRail, Confluence, and Postman;
• Basic knowledge of Unix / command line;
• Understanding of CI/CD processes (nice to have);
• Basic knowledge of Docker/containerization is a plus;

• English — Intermediate or higher;

   

Responsibilities

• Communicate with product owners and developers to ensure alignment with project goals;
• Participate in product development activities from early stages, providing QA feedback;
• Identify, document, and track bugs throughout the development process;
• Develop and maintain test cases, checklists, and bug reports;
• Test the product across different mobile devices and operating system versions;
• Collaborate effectively within the team, maintaining a proactive and results-driven approach;
• Ensure accuracy, responsibility, and attention to detail in all testing activities.

Benefits

Why Join Us?

🎰 Be part of the international iGaming industry – Work with a top European solution provider and shape the future of online gaming;

💕 A Collaborative Culture – Join a supportive and understanding team;

💰 Competitive salary and bonus system – Enjoy additional rewards on top of your base salary;

📆 Unlimited vacation & sick leave – Because we prioritize your well-being;

📈 Professional Development – Access a dedicated budget for self-development and learning;

🏥 Healthcare coverage – Available for employees in Ukraine and compensation across the EU;

🫂 Mental health support – Free consultations with a corporate psychologist;

🇬🇧 Language learning support – We cover the cost of foreign language courses;

🎁 Celebrating Your Milestones – Special gifts for life’s important moments;

⏳ Flexible working hours – Start your day anytime between 9:00-11:00 AM;

🏢 Flexible Work Arrangements – Choose between remote, office, or hybrid work;

🖥 Modern Tech Setup – Get the tools you need to perform at your best;

🚚 Relocation support – Assistance provided if you move to one of our hubs.

Billease is seeking a Deputy Chief Technology Officer (Deputy CTO) who will serve as a senior technical authority and a trusted partner to the CTO. This role requires deep hands-on expertise, a strong theoretical foundation, and proven experience designing, building, and operating complex systems within a fintech environment.

The Deputy CTO will independently drive architectural decisions, ensure platform stability, security, and scalability, and effectively bridge engineering execution with business and regulatory requirements. 

Architecture & Technical Leadership

• Design, evolve, and govern scalable, secure, and highly available architectures.
• Strong experience with microservices, event-driven systems, and modular monoliths, with clear trade-off analysis.
• Deep grounding in design patterns, SOLID principles, and Clean Architecture.
• Lead architecture and code reviews, technical due diligence, and major design decisions.
• Own and maintain architecture documentation (C4, ADRs, diagrams).

Platform, Cloud & Infrastructure

• Hands-on leadership of production Kubernetes environments (EKS/GKE).
• Strong knowledge of Helm, ingress controllers, autoscaling (HPA/VPA), and zero-downtime deployment strategies (blue-green, canary, rolling).
• Deep experience with AWS (VPC, EC2, EKS, RDS, S3, Route53, Load Balancers) and working knowledge of GCP (GKE, Pub/Sub, Cloud SQL).
• Design secure, highly available, cost-efficient multi-AZ cloud architectures.
• Strong understanding of IAM, backups, disaster recovery, and cost governance.

Security & Reliability

• Strong information security mindset aligned with financial-grade standards.
• Experience with encryption (in transit/at rest), key management, secrets storage, VPNs, and secure networking.
• Solid networking fundamentals: TCP/IP, routing, firewalls, DNS, and load balancing.
• Ownership of observability and reliability practices using Prometheus, Grafana, Victoria Metrics, logs, metrics, traces, alerts, and SLOs.

Backend, Data & Messaging

• Strong hands-on experience with Python (FastAPI/Flask/Django) and Golang for high-performance services.
• Deep understanding of Linux and Docker (multi-stage builds, runtime security).
• Experience with messaging and streaming platforms (Kafka, RabbitMQ), including retries, DLQs, and delivery semantics.
• Strong database expertise: PostgreSQL, MySQL, ClickHouse, SQL optimization, and familiarity with NoSQL systems.
• Experience with logging/search stacks (ELK).
• Solid understanding of data warehousing and pipelines (Redshift, Airflow, ETL/ELT, data quality).

Fintech, Payments & Domain Knowledge (Mandatory)

• Proven experience working in a fintech company.
• Strong understanding of regulatory and compliance constraints, risk management, and security requirements.
• Hands-on knowledge of card payment systems (authorization, clearing, settlement), PCI-DSS, payment gateways, and 3-D Secure.
• Understanding of end-to-end transaction flows, reconciliation, and financial reporting.
• Experience supporting collections systems or workflows is a strong advantage.

Mobile & Integrations

• Ability to review and guide high-scale mobile applications (Android: Kotlin/Java, iOS: Swift).
• Experience collaborating with mobile teams on API design, security, performance, and release coordination.
• Strong experience designing and debugging integrations using standard internet protocols (HTTPS, SMTP, SFTP).

Leadership & Ways of Working

• Proven experience leading senior engineering teams and acting as a technical authority.
• Ability to mentor engineers, provide structured feedback, and drive execution.
• Experience hiring and onboarding senior engineers is a plus.
• Strong Agile and delivery management skills (Scrum/Kanban), including backlog prioritization, release planning, risk management, and stakeholder communication.
• Strong Git and CI/CD practices.

We are looking for a Sales / Business Development Manager focused on new business development and account expansion within the digital / marketing services domain.

The role requires a proactive hunter mindset, strong B2B sales experience, and the ability to align client commitments with actual delivery capabilities.

Key Responsibilities

• Drive new business acquisition through outbound and lead generation activities
• Conduct first communication, qualification, and pitching
• Work with cold leads and build a sustainable pipeline
• Identify client pain points and convert them into closed deals
• Ensure alignment between client expectations and delivery capabilities
• Maintain high CRM discipline: forecasting, documentation, reporting
• Collaborate closely with internal delivery teams
   

Requirements

• 2+ years of experience in B2B sales
• Experience working in digital / marketing agencies (Digital services, IT products for B2B)
• Proven experience working in an International  environment (B2+ level or higher)
• Strong lead generation and cold outreach experience
• Negotiation skills
• Strong understanding of delivery capabilities and technical feasibility
• Experience working with CRM systems
   

Nice to Have

• High-ticket sales experience (retainers, long-term contracts)
• Deal closing ownership
• German language
• Continuous professional development and training participation
   

Interview Process

• Recruiter screen (30–45 min)
• Interview with Hiring Manager (30 min)
• CASE Interview (~60 min)
• Reference check
• Offer call

What you’ll do

• Plan and execute test cycles for Android POS app versions: smoke, regression, and exploratory
• Verify releases end-to-end: changelog validation, build sanity, OTA/update flows, and final sign-off
• Perform ticket verification: reproduce, validate fixes, and close with clear evidence and test notes
• Test on physical POS devices (e.g., K6-class terminals): peripherals (printers, scanners, card readers), EMV/NFC, receipts
• Validate critical POS user flows: checkout, refunds/voids, settlements, offline/poor-network scenarios
• Manage device/OS matrix: Android versions, form factors, firmware, and compatibility impacts
• Design, author, and maintain high-quality test cases and edge-case scenarios for core flows
• Design and execute API tests for POS-related backend services: validate request/response payloads, error handling, and contracts that support mobile flows
• Capture diagnostics for defects: logs, screenshots, videos, ADB traces; provide precise repro steps
• Collaborate with engineering/product to define acceptance criteria and improve testability
• Track quality signals and risks; prioritize test coverage based on impact and usage

What you’ll bring

• Strong POS domain expertise: payments flows, EMV/contactless, peripherals, and store operations
• Hands-on experience testing Android apps on dedicated POS hardware
• Proven history executing version testing: feature, regression, and hotfix validation across releases
• Solid test case design skills (boundary, risk-based, negative paths) and meticulous documentation
• Proficiency with Android test tooling basics: ADB, logcat, device settings, and network conditioning
• Comfortable verifying tickets end-to-end: reproducing issues, validating fixes, and closing with evidence
• Attention to detail, ownership of release quality, and clear communication with cross-functional teams
• Familiarity with test management tools like Testrail, practical API testing knowledge (e.g., REST/JSON, status codes, basic contract validation), and CI acceptance checks