Thunes Software Engineer interview questions & guide 2026

The following questions are representative of what you will encounter during the Thunes selection process. They are compiled from real candidate experiences across global offices and are designed to test your core technical knowledge, architectural thinking, and alignment with the company's engineering standards.

API Design & System Architecture

This category evaluates your ability to design scalable, secure, and resilient web services, which is a core daily responsibility for engineers at Thunes.

• How would you design a highly available mobile wallet solution that supports real-time transactions?
• Explain the differences between various HTTP methods (GET, POST, PUT, DELETE, PATCH) and when you would use each in an API design.

To succeed in the Thunes interview process, you must demonstrate a unique blend of deep technical execution and structured problem-solving. Interviewers look for clean code, robust architectural patterns, and a solid understanding of how financial data flows securely.

API Design & Architecture – You must be able to design RESTful APIs that are clean, intuitive, and highly secure. Be prepared to explain your choices regarding HTTP status codes, payload structures, authentication, and rate limiting.

Golang & Technical Proficiency – If you are interviewing for a Go-focused role, expect deep dives into Go internals, concurrency primitives, and memory management. You should show that you can write idiomatic, high-performance code that handles high throughput.

Agile Collaboration & Code Quality – At Thunes, engineers own their code. You will need to show a strong commitment to Agile methodologies, Test-Driven Development (TDD), and Continuous Integration/Continuous Deployment (CI/CD) pipelines.

Resilience & Communication – The interview process can be challenging and sometimes requires managing long timelines or heavy technical assignments. Demonstrating clear communication, patience, and proactive follow-up is highly valued.

The interview process at Thunes is designed to evaluate both your practical coding skills and your high-level architectural thinking. It typically spans several weeks and involves multiple touchpoints with both recruiters and senior technical leadership, including Tech Leads, the Head of Architecture, or even the CTO.

The journey begins with an initial screening call with a recruiter to discuss your background, motivations, and overall experience. For some roles, this may be accompanied or followed by a brief video recording or a short technical screening focusing on basic web concepts and security. Once you pass the initial screen, you will move into the core technical evaluation phases.

The defining characteristic of the Thunes technical pipeline is a comprehensive take-home coding assignment. This challenge typically requires you to build a functional API or microservice (such as a mobile wallet or transaction engine) using Golang or your language of choice. Following a successful review of your code, you will participate in deep-dive technical interviews, which may include a presentation of your assignment, live screen-share coding sessions, algorithm tests, and system design discussions with architecture leads.

The timeline above outlines the typical progression from the initial recruiter contact to the final decision. While the stages are structured to ensure a thorough evaluation, candidates should note that the overall process can sometimes take several weeks to complete due to the thorough review of the take-home assignment by multiple team members. Use this timeline to pace your preparation, focusing heavily on API design and Go fundamentals before receiving the take-home challenge.

API Design and Event-Driven Architecture

At Thunes, you will build services that process millions of transactions. Your ability to design resilient, decoupled APIs and handle asynchronous communication is critical to maintaining network reliability.

Be ready to go over:

• RESTful API Best Practices – Designing consistent endpoints, proper utilization of HTTP methods, handling pagination, and structured error responses.
• Message Brokers – Implementing event-driven patterns using AWS SNS/SQS, Apache Kafka, or RabbitMQ to decouple microservices.

As a Software Engineer at Thunes, your daily work directly supports the continuous expansion of the global payment network. You will be responsible for developing, deploying, and maintaining highly available services that interface with hundreds of financial partners worldwide.

You will collaborate closely with a diverse, global team of engineers, product managers, and system architects spread across 14 locations. Your role requires a strong sense of ownership over the entire software development lifecycle. You will not just write code; you will also design the architecture, write tests, configure CI/CD pipelines, and monitor your services in production to ensure they meet strict Service Level Agreements (SLAs).

Typical initiatives you will drive include integrating new payment methods (such as mobile wallets or local card networks), optimizing the performance of the core SmartX Treasury System, and enhancing the security features of the Fortress Compliance Platform. You will also participate actively in Agile ceremonies, contributing to daily stand-ups, sprint planning, and constructive peer code reviews.

To be competitive for a Software Engineer position at Thunes, you must demonstrate a strong technical foundation and a collaborative, growth-oriented mindset.

• Must-have skills – Proficient in Golang (or a strong background in backend languages like Java/C++ with a proven ability to transition), solid experience designing RESTful APIs, and deep familiarity with relational databases (PostgreSQL or MySQL).
• Nice-to-have skills – Experience with Event-Driven Architecture (AWS SNS/SQS, Kafka, RabbitMQ), familiarity with cloud environments (AWS), and previous exposure to the fintech or payments industry.
• Experience level – Typically 3+ years of professional backend engineering experience for mid-level roles, and 5+ years with a track record of architectural leadership for senior roles.
• Soft skills – Strong communication skills to collaborate across global time zones, a curious and self-motivated learning attitude, and a commitment to clean code and Agile practices.

Q: What is the most challenging part of the Thunes interview process? A: Most candidates find the take-home technical assignment to be the most demanding stage. It requires a significant time investment to build a fully functional, production-ready service. Ensuring your code is modular, well-tested, and clearly documented is key to advancing.

Q: Does Thunes allow remote or hybrid working? A: Yes, Thunes supports a flexible and hybrid working policy, allowing you to balance working from their modern offices (such as the Barcelona office near Sagrada Familia) with working from home.

Q: How long does the entire interview process typically take? A: The timeline can vary depending on the location and team availability. It typically takes between 3 to 6 weeks from the initial screen to the final offer, though some candidates have experienced longer timelines. Staying proactive with your recruiter is highly recommended.

Q: What differentiates a successful candidate from one who gets rejected? A: Successful candidates demonstrate strong code ownership, clean architectural practices in their take-home test, and clear communication. Candidates who fail often submit rushed code lacking tests or fail to follow up effectively during the multi-stage process.

• Proactively manage your application status: Because the hiring process involves multiple stakeholders across different regions, communication can sometimes experience delays. If you do not hear back within a few days of submitting your take-home assignment, send a polite follow-up email to your recruiter.

• Brush up on financial transaction concepts: You do not need to be a fintech expert, but understanding basic payment flows, ledger systems, double-entry bookkeeping, and transaction states will give you a significant advantage during system design discussions.

• Optimize for readability over cleverness: During live coding or in your take-home test, prioritize clean, readable, and idiomatic code over overly complex algorithms. Thunes values maintainability and ease of collaboration above all.

Preparing for a Software Engineer role at Thunes requires a dedicated focus on building secure, scalable, and highly performant backend systems. By mastering Golang fundamentals, refining your API design skills, and preparing a stellar take-home assignment, you can set yourself apart as a top-tier candidate.

Remember that Thunes is looking for engineers who are excited to take ownership of their work and contribute to a global financial revolution. Approach each stage of the interview with confidence, clarity, and a collaborative mindset.

The salary range shown above reflects the broad global footprint of Thunes, spanning multiple markets from Europe to Asia. Your final compensation package will be tailored to your specific location, experience level, and local market standards, and typically includes competitive performance bonuses and comprehensive health benefits.

To gain more insights, practice real interview scenarios, and connect with other candidates who have gone through the process, explore the extensive resources available on Dataford. Good luck with your preparation!