Senior QA Engineer

Wallex is a FinTech company providing a secure cryptocurrency exchange platform and digital asset payment solutions.

With a vision to become a leading global FinTech enterprise, Wallex is recognized as one of the largest cryptocurrency exchange platforms in Iran, supporting the online trading of over 130 cryptocurrencies.

We are seeking a Senior QA Engineer to join our Blockchain team and help ensure the reliability, security, and correctness of our blockchain-related services and integrations.

In this role, you will work closely with Backend Engineers, Blockchain Engineers, DevOps, Product, and other QA Engineers to validate complex systems involving blockchain networks, wallets, transactions, deposits, withdrawals, and internal financial services. We are looking for someone with a strong Quality Engineering background, solid API and backend testing experience, hands-on automation skills, and the ability to investigate complex blockchain-related workflows at a technical level.

Responsibilities:

• Design, review, and execute comprehensive test scenarios for blockchain-related services and financial workflows.
• Perform manual, API, integration, regression, exploratory, and end-to-end testing across backend services and supporting applications.
• Validate blockchain transaction flows, including deposits, withdrawals, confirmations, failed or rejected transactions, pending transactions, network delays, reorganizations, and other blockchain-specific edge cases.
• Test wallet functionality, address generation, transaction tracking, and balance synchronization.
• Validate integrations with blockchain nodes, RPC providers, third-party blockchain services, internal microservices, and databases.
• Verify data consistency across blockchain networks, internal services, databases, and user balances.
• Design, implement, and maintain scalable automated tests for APIs, backend services, integration flows, and user-facing functionality where applicable.
• Write clear and maintainable test scenarios and acceptance criteria using Gherkin / BDD syntax.
• Analyze technical requirements to identify missing scenarios, edge cases, potential failures, and quality risks before implementation.
• Validate REST APIs, RPC interfaces, WebSocket-based services, asynchronous processes, and event-driven workflows.
• Investigate staging and production issues using logs, databases, blockchain explorers, monitoring tools, and service responses.
• Reproduce complex defects and provide engineers with detailed technical information to support root cause analysis and debugging.
• Participate in code reviews and test reviews from a quality and testability perspective.
• Review test coverage before releases and ensure critical blockchain and financial scenarios are properly validated.
• Contribute to CI/CD pipelines, automated quality gates, and the stability and maintainability of the automation suite.
• Collaborate with engineering teams to improve system observability, testability, and overall software quality.
• Mentor other QA Engineers and contribute to defining QA standards and best practices within the team.

Requirements:

• Strong professional experience in Software Quality Assurance or Quality Engineering.
• Strong hands-on experience with API and backend testing.
• Good understanding of REST APIs, HTTP, JSON, authentication mechanisms, status codes, headers, and client-server architecture.
• Hands-on experience with API testing tools such as Postman, Swagger/OpenAPI tools, or equivalent solutions.
• Experience designing and implementing test automation using at least one programming or scripting language.
• Experience with UI automation tools such as Selenium, Playwright, Cypress, or similar frameworks.
• Ability to design maintainable, reusable, and scalable automated test suites.
• Experience writing test scenarios and acceptance criteria using Gherkin / BDD.
• Strong knowledge of functional, integration, regression, exploratory, and end-to-end testing.
• Good understanding of asynchronous systems, distributed architectures, and event-driven workflows.
• Experience validating data using SQL databases and backend systems.
• Experience with Git, CI/CD pipelines, and modern software development workflows.
• Ability to independently investigate complex technical issues and identify root causes.
• Strong analytical thinking, attention to detail, communication, and cross-functional collaboration skills.
• Good understanding of blockchain fundamentals, including transaction lifecycle, blocks and confirmations, wallets and addresses, network fees, nodes and RPC interfaces, Mainnet and Testnet environments, token and native asset transfers, transaction hashes, and blockchain explorers.
• Understanding of pending, confirmed, failed, and dropped transactions, as well as blockchain network latency and temporary consistency issues.
• Conceptual understanding of public and private keys and the ability to investigate blockchain-related issues without requiring deep blockchain development experience.

Nice to Have:

• Previous experience working with cryptocurrency exchanges, FinTech platforms, wallets, or blockchain products.
• Experience testing integrations with networks such as Bitcoin, Ethereum, TRON, or similar blockchains.
• Experience working directly with blockchain RPC APIs and familiarity with Web3 concepts and tools.
• Experience with TypeScript, JavaScript, or Node.js for test automation.
• Experience with Selenium, Playwright, Jest, or similar testing frameworks.
• Experience testing microservice-based, asynchronous, and event-driven systems.
• Familiarity with message brokers such as Kafka or RabbitMQ.
• Experience with Redis or NoSQL databases.
• Familiarity with Docker and Kubernetes.
• Experience with performance and load testing.
• Familiarity with monitoring and observability tools such as Grafana, Kibana, or similar platforms.
• Basic understanding of smart contracts and token standards such as ERC-20.

We build, not watch — This is where you belong!