Fast Software Engineer Interview Questions + Guide in 2025

Fast is a cutting-edge technology company focused on streamlining online transactions and enhancing user experiences through innovative software solutions.

As a Software Engineer at Fast, you will be responsible for designing, developing, and maintaining high-performance software applications that drive the company's core business objectives. Key responsibilities include collaborating with cross-functional teams to gather requirements, implementing efficient algorithms, and ensuring code quality through rigorous testing and documentation. You will leverage your expertise in programming languages such as Java, Python, or JavaScript, and utilize databases to support various applications. A strong understanding of object-oriented programming principles and software development methodologies is essential, along with a passion for problem-solving and delivering user-centric solutions.

Given Fast's emphasis on teamwork and a positive company culture, traits such as adaptability, effective communication, and a willingness to learn new technologies will significantly enhance your fit for the role. Your ability to explain complex technical concepts to non-technical stakeholders will also be valuable, as you may need to guide clients through software integrations and solutions.

This guide aims to equip you with the knowledge and insights to confidently navigate the interview process at Fast, helping you stand out as a candidate who aligns well with the company's mission and values.

The interview process for a Software Engineer at Fast is structured and designed to assess both technical skills and cultural fit. It typically consists of several key stages that candidates can expect.

1. Initial Phone Interview

The process begins with a 25-30 minute phone interview, usually conducted by a recruiter. This initial conversation focuses on getting to know the candidate, discussing their background, and understanding their motivations for wanting to work at Fast. Expect a mix of behavioral questions and a few basic technical inquiries, such as concepts related to object-oriented programming and Java.

2. Technical Assessment

Following the initial screen, candidates may be invited to complete a technical assessment. This can take the form of a live coding session or a logic quiz, where candidates are asked to solve problems using pseudocode or answer logic puzzles. The goal is to evaluate problem-solving abilities and coding proficiency. Candidates should be prepared to explain their thought process as they work through the problems.

3. Technical Interview

Candidates who perform well in the technical assessment will typically move on to a more in-depth technical interview. This interview often lasts about an hour and may involve one or more software engineers. Expect questions that cover a range of topics, including data structures, algorithms, and specific programming languages. Candidates may also be asked to write code on a shared screen or whiteboard, demonstrating their coding skills in real-time.

4. Behavioral and Cultural Fit Interview

In addition to technical skills, Fast places a strong emphasis on cultural fit. Candidates may have a separate interview focused on behavioral questions and situational scenarios. This part of the process assesses how well candidates align with the company's values and work environment. Questions may involve hypothetical situations or past experiences that reveal how candidates handle challenges and collaborate with others.

5. Final Interview

The final stage may involve a wrap-up interview with HR or senior management. This interview often covers logistical aspects such as relocation, work preferences, and any remaining questions the candidate may have about the role or the company. It’s also an opportunity for candidates to express their enthusiasm for the position and clarify any details about the job.

As you prepare for your interview, consider the types of questions that may arise during each stage of the process.

Here are some tips to help you excel in your interview.

Understand the Company Culture

Fast values a respectful and organized interview process, so approach your interview with professionalism and courtesy. Familiarize yourself with the company's mission and values, and be prepared to articulate why you want to work there. Reflect on how your personal values align with those of Fast, as this will resonate well with your interviewers.

Prepare for Technical Questions

While the technical questions may not be overly complex, you should still be ready to demonstrate your coding skills and understanding of fundamental concepts. Brush up on Java basics, including the differences between JRE and JVM, as well as object-oriented programming principles like inheritance and polymorphism. Practice writing pseudocode and solving simple coding problems, as these are common in interviews.

Emphasize Problem-Solving Skills

Interviewers at Fast appreciate candidates who can think critically and articulate their thought processes. When faced with coding or logic problems, take your time to explain your approach. This not only showcases your technical skills but also your ability to communicate effectively, which is crucial in a collaborative environment.

Be Ready for Behavioral Questions

Expect a mix of technical and behavioral questions. Prepare to discuss your past experiences, strengths, and weaknesses. Use the STAR (Situation, Task, Action, Result) method to structure your responses, ensuring you provide clear and concise examples that highlight your problem-solving abilities and teamwork.

Show Willingness to Relocate

Fast often requires employees to move for projects, so be prepared to discuss your flexibility regarding relocation. If you have any preferences or concerns, address them openly during the interview. This will demonstrate your willingness to adapt and your commitment to the role.

Ask Insightful Questions

At the end of the interview, you will likely have the opportunity to ask questions. Use this time to inquire about team dynamics, project expectations, and growth opportunities within the company. This not only shows your interest in the role but also helps you gauge if Fast is the right fit for you.

Follow Up

After your interview, send a thank-you email to express your appreciation for the opportunity. This is a chance to reiterate your interest in the position and reflect on any key points discussed during the interview. A thoughtful follow-up can leave a lasting impression and set you apart from other candidates.

By preparing thoroughly and approaching the interview with confidence and authenticity, you can position yourself as a strong candidate for the Software Engineer role at Fast. Good luck!

In this section, we’ll review the various interview questions that might be asked during a Software Engineer interview at Fast. The interview process will likely assess your technical skills, problem-solving abilities, and cultural fit within the company. Be prepared to discuss your experience with programming languages, algorithms, and software development principles, as well as your approach to teamwork and communication.

Technical Knowledge

1. What is the difference between JRE and JVM?

Understanding the Java Runtime Environment (JRE) and Java Virtual Machine (JVM) is crucial for any software engineer working with Java.

How to Answer

Explain the roles of JRE and JVM in the Java ecosystem, emphasizing how JRE provides the libraries and components necessary for running Java applications, while JVM is responsible for executing the bytecode.

Example

“JRE is the Java Runtime Environment that provides the necessary libraries and components to run Java applications, while JVM is the Java Virtual Machine that executes the bytecode generated by the Java compiler. Essentially, JRE is the environment in which Java programs run, and JVM is the engine that drives the execution.”

2. Can you explain the concept of inheritance in object-oriented programming?

Inheritance is a fundamental concept in OOP, and being able to articulate it clearly is important.

How to Answer

Define inheritance and provide a simple example to illustrate how it allows a class to inherit properties and methods from another class.

Example

“Inheritance is a mechanism in object-oriented programming that allows one class to inherit the properties and methods of another class. For instance, if we have a base class called ‘Animal’ and a derived class called ‘Dog,’ the ‘Dog’ class can inherit characteristics like ‘bark’ from the ‘Animal’ class.”

3. Describe polymorphism in simple terms.

Polymorphism is another key OOP concept that you should be able to explain clearly.

How to Answer

Discuss how polymorphism allows methods to do different things based on the object that it is acting upon, and provide a relatable analogy.

Example

“Polymorphism allows methods to perform different functions based on the object that invokes them. For example, if we have a method called ‘makeSound’ in both ‘Dog’ and ‘Cat’ classes, calling ‘makeSound’ on a ‘Dog’ object would return ‘bark,’ while on a ‘Cat’ object, it would return ‘meow.’”

4. What are the different types of loops in programming?

Being familiar with control structures is essential for any software engineer.

How to Answer

List the common types of loops and briefly describe their use cases.

Example

“The main types of loops in programming are ‘for’ loops, ‘while’ loops, and ‘do-while’ loops. A ‘for’ loop is typically used when the number of iterations is known, while a ‘while’ loop continues until a specified condition is false. A ‘do-while’ loop is similar but guarantees at least one iteration.”

Problem Solving

5. Write a function to multiply two integers without using the multiplication operator.

This question tests your problem-solving skills and understanding of basic algorithms.

How to Answer

Discuss your thought process and approach to solving the problem, focusing on using addition in a loop or recursion.

Example

“To multiply two integers without using the multiplication operator, I would use a loop to add one integer to itself repeatedly based on the value of the other integer. For instance, if we want to multiply 3 by 4, I would add 3 a total of 4 times, resulting in 12.”

6. How would you explain the concept of passing by value and passing by reference?

Understanding how data is passed in programming languages is crucial for effective coding.

How to Answer

Define both concepts and explain the implications of each on data manipulation.

Example

“Passing by value means that a copy of the variable is passed to the function, so changes made to the parameter do not affect the original variable. In contrast, passing by reference means that a reference to the original variable is passed, allowing the function to modify the original variable directly.”

Logic and Analytical Thinking

7. If you have 25 horses and can only race 5 at a time, how do you determine the three fastest horses in 7 races?

This question assesses your logical reasoning and problem-solving skills.

How to Answer

Outline a systematic approach to solving the problem, focusing on elimination and comparison.

Example

“To determine the three fastest horses, I would first race the 25 horses in 5 groups of 5, which gives me the top horse from each group. Then, I would race the top horses from each group to find the fastest overall. From there, I can determine the second and third fastest by comparing the horses that finished closely behind the top horse in the previous races.”

8. You have a 4-minute and a 7-minute hourglass. How do you count to 9 minutes exactly?

This question tests your ability to think outside the box and use available resources creatively.

How to Answer

Explain the steps you would take to measure the time accurately using the hourglasses.

Example

“To measure 9 minutes, I would start both hourglasses at the same time. When the 4-minute hourglass runs out, I flip it immediately. When the 7-minute hourglass runs out, I flip it as well. When the 4-minute hourglass runs out again, 8 minutes will have passed, and I can then wait for 1 more minute to reach a total of 9 minutes.”

Behavioral and Cultural Fit

9. What about Fast makes you want to work here?

This question assesses your motivation and alignment with the company’s values.

How to Answer

Discuss specific aspects of the company culture, mission, or projects that resonate with you.

Example

“I am drawn to Fast because of its commitment to innovation and collaboration. I appreciate the emphasis on teamwork and the opportunity to work on impactful projects that enhance user experiences. The company’s values align with my own, and I am excited about the potential to contribute to a forward-thinking team.”

10. Describe a time when you had to convince a client or team member to see things your way.

This question evaluates your communication and persuasion skills.

How to Answer

Provide a specific example that highlights your ability to articulate your ideas and influence others.

Example

“In a previous project, I had to convince my team to adopt a new technology that I believed would improve our workflow. I presented data on its benefits, demonstrated its ease of use, and addressed their concerns. By showing how it aligned with our goals, I was able to gain their support and successfully implement the technology.”