1. What is a Software Engineer at AvidXchange?

As a Software Engineer at AvidXchange, you are at the forefront of transforming how middle-market companies manage their accounts payable and B2B payments. AvidXchange operates a massive, highly secure SaaS platform that processes millions of transactions, making engineering excellence a fundamental requirement for the business. In this role, you are not just writing code; you are building the financial infrastructure that thousands of businesses rely on daily.

Your impact will span across developing robust backend services, optimizing complex database queries, and ensuring seamless user experiences. Because the platform handles sensitive financial data at scale, your work directly influences the security, reliability, and efficiency of the core product. You will collaborate closely with cross-functional teams, including product managers and operations, to translate intricate business requirements into scalable technical solutions.

Expect a role that challenges you to balance rapid feature delivery with uncompromising systemic stability. The engineering culture at AvidXchange values strong foundational knowledge, operational awareness, and the ability to navigate complex domain logic. If you thrive in environments where your technical decisions have an immediate, measurable impact on business operations, this role will be deeply rewarding.

2. Common Interview Questions

The following questions represent the types of challenges you will face during the AvidXchange interview process. They are drawn from patterns observed in past candidate experiences and are designed to test the specific areas AvidXchange values most.

Data Structures and Algorithms (Karat Round)

This category tests your ability to write clean, efficient code under time pressure. Expect to solve 2-3 questions in 45 minutes.

• Implement a Depth-First Search (DFS) algorithm to find a specific node in a graph.
• Given a string, find the longest substring without repeating characters.
• Write a function to determine if a given graph is bipartite.
• Given an array of integers, return the indices of the two numbers that add up to a specific target.
• Traverse a matrix to calculate the maximum path sum from the top-left to the bottom-right.

System and API Design

These questions, often asked in quick succession, test your architectural intuition and ability to handle ambiguous requirements.

• Given a scenario where an application needs to securely process daily batch files, how would you design the system?
• Design a RESTful API for a user management system. What HTTP methods and status codes would you use?
• If an API request requires fetching data from three different microservices, how do you handle partial failures?
• How would you structure the database schema for a multi-tenant SaaS application?

Core Technologies and SQL

These questions appear in the final rounds with AvidXchange engineers and test your practical, on-the-job knowledge.

• Write a SQL query to retrieve specific relational data without using any aggregate functions (e.g., no SUM, COUNT, MAX).
• Explain the concept of indexing in SQL. How does it work, and when would you avoid using it?
• Walk me through how asynchronous programming and Promises work in JavaScript.
• Explain the four pillars of Object-Oriented Programming and provide an example of how you use them in .NET.
• What DevOps principles do you follow to ensure your code is safely deployed to production?

Behavioral and Cultural Fit

These questions assess your alignment with AvidXchange's environment and your professional background.

• What do you know about AvidXchange, and why do you want to work here?
• Tell me about a time you had to explain a complex technical concept to a non-technical stakeholder.
• Describe a project on your resume where you had to overcome a significant technical hurdle.
• How do you handle a situation where the requirements for a feature are vague or constantly changing?

3. Getting Ready for Your Interviews

Preparing for the Software Engineer interview at AvidXchange requires a strategic approach. The evaluation process is designed to test both your foundational computer science knowledge and your practical, on-the-job engineering skills.

To succeed, you must demonstrate proficiency across the following key evaluation criteria:

• Algorithmic Problem Solving – You must be able to write clean, optimized code under time constraints. Interviewers evaluate your ability to identify the right data structures and algorithms, particularly in high-pressure, standardized testing environments.
• System and API Design – AvidXchange relies heavily on interconnected services. You will be assessed on how you architect solutions, design clean APIs, and handle ambiguous scenarios by asking the right clarifying questions.
• Domain-Specific Technical Depth – Your practical knowledge of core technologies is heavily scrutinized. Interviewers look for deep understanding of SQL optimization, object-oriented programming (OOP) principles, JavaScript asynchronous behavior, and .NET fundamentals.
• Operational Excellence and DevOps – Beyond writing code, you are evaluated on your understanding of how software is deployed, monitored, and maintained. Demonstrating knowledge of DevOps principles shows you understand the full software lifecycle.
• Culture Fit and Adaptability – Interviewers want to see how you handle feedback, communicate your thought process, and align with the mission of AvidXchange. Your ability to remain calm and structured, even when faced with poorly defined problems, is critical.

4. Interview Process Overview

The interview process for a Software Engineer at AvidXchange is structured to efficiently filter candidates through a blend of internal behavioral screening and standardized, third-party technical assessments. You will typically begin with an initial phone screen with an internal recruiter. This conversation is focused on your background, your interest in AvidXchange, and high-level technical alignment. While mostly behavioral, be prepared for recruiters to ask basic technical trivia and take exact notes on your answers.

Following the initial screen, the technical heavy lifting begins with an outsourced technical interview conducted by Karat. This is a highly structured, one-hour session split between scenario-based API design questions and Leetcode-style coding challenges. Because this round is conducted by a third party, it can feel scripted and impersonal. Your goal here is to play by the rules of the standardized test: communicate clearly, ask clarifying questions, and write functional code swiftly.

If you pass the Karat screen, you will move to the final rounds, which consist of technical and behavioral interviews with AvidXchange engineers and engineering managers. These sessions are much more conversational and dive deep into your resume, your understanding of core technologies like SQL and .NET, and your cultural fit within the team.

This visual timeline outlines the typical progression from the initial recruiter screen to the final panel interviews. Use this to pace your preparation, focusing heavily on standard Data Structures and Algorithms (DSA) for the middle stage, and pivoting to deep, domain-specific trivia and system architecture for the final rounds. Note that timelines can occasionally stretch, so patience and proactive follow-ups are beneficial.

5. Deep Dive into Evaluation Areas

To excel in the AvidXchange interview process, you must be prepared to navigate distinct technical and behavioral evaluation areas. The process is bifurcated between standardized algorithmic testing and practical, domain-specific engineering discussions.

Data Structures and Algorithms (The Karat Interview)

The most critical hurdle for many candidates is the outsourced Karat interview. This area tests your raw coding speed, accuracy, and foundational computer science knowledge. Strong performance means solving at least two, ideally three, problems within a strict 45-minute window.

Be ready to go over:

• Graph Traversal – Deep understanding of Depth-First Search (DFS) and Breadth-First Search (BFS) is frequently tested.
• String and Array Manipulation – Core algorithmic patterns like sliding window or two-pointer techniques.
• Time and Space Complexity – You must be able to articulate the Big O notation for every solution you write.
• Advanced concepts (less common) – Dynamic programming or complex tree balancing, though these appear less frequently than standard graph problems.

Example questions or scenarios:

• "Given a grid representing a map, use DFS to find the number of distinct islands."
• "Write a function to determine if a directed graph contains a cycle."
• "Implement an algorithm to traverse a nested data structure and return a flattened array."

System and API Design

During the first 15 minutes of the Karat interview, and later in discussions with AvidXchange engineers, you will be evaluated on your system design intuition. This area tests how you structure data and endpoints for scalability and usability. Strong candidates do not just answer the prompt; they clarify the context before designing.

Be ready to go over:

• RESTful API Design – Best practices for routing, HTTP methods, and status codes.
• Data Modeling – How to structure database tables to support the proposed API.
• Handling Ambiguity – Navigating poorly phrased or context-lacking scenarios by asking targeted questions.
• Advanced concepts (less common) – Microservices communication, rate limiting, and caching strategies.

Example questions or scenarios:

• "Given a scenario where users need to upload and process large invoices, how would you design the API endpoints?"
• "Design a schema and API for a system that tracks user permissions across multiple organizations."
• "How would you handle a scenario where an API request fails halfway through a database transaction?"

Core Technologies: SQL, JavaScript, and .NET

Once you reach the internal AvidXchange interviews, the focus shifts dramatically to the practical technologies used on the job. Interviewers want to ensure you can contribute to their specific stack immediately. Strong performance here requires moving beyond surface-level knowledge and demonstrating a deep understanding of how these languages operate under the hood.

Be ready to go over:

• Advanced SQL – Deep knowledge of indexing, query optimization, and complex joins. You will be asked to write queries under specific constraints.
• JavaScript Fundamentals – Deep dive into asynchronous programming, Promises, and the event loop.
• OOP and .NET – Core object-oriented principles (Encapsulation, Inheritance, Polymorphism, Abstraction) and .NET framework fundamentals.
• Advanced concepts (less common) – CI/CD pipelines, containerization, and specific DevOps practices.

Example questions or scenarios:

• "Write a SQL query to find the second highest salary in a department, but you are absolutely not allowed to use any aggregate functions (like MAX or COUNT)."
• "Explain how Promises work in JavaScript and how you would handle multiple asynchronous API calls."
• "Discuss how you apply SOLID principles in a .NET application to ensure maintainability."

6. Key Responsibilities

As a Software Engineer at AvidXchange, your day-to-day work is centered around building, optimizing, and maintaining the systems that power B2B payment automation. You will be responsible for developing scalable backend services, frequently utilizing C# and .NET, while also managing frontend components using modern JavaScript frameworks.

A significant portion of your time will be spent interacting with databases. You will write, review, and optimize complex SQL queries to ensure that large volumes of financial data are retrieved and processed efficiently. Because performance is critical in financial technology, you will constantly monitor system health and refactor legacy code to improve execution speed and reduce technical debt.

Collaboration is a daily requirement. You will work alongside product managers to understand new feature requirements, coordinate with QA engineers to ensure robust test coverage, and partner with DevOps teams to streamline deployment pipelines. You will also participate in daily stand-ups, architecture review meetings, and code reviews, ensuring that all code adheres to AvidXchange's strict security and quality standards.

7. Role Requirements & Qualifications

To be a competitive candidate for the Software Engineer position at AvidXchange, you must possess a blend of strong algorithmic thinking and practical, stack-specific experience. The company looks for engineers who can hit the ground running while adapting to their established engineering culture.

• Must-have technical skills – Deep proficiency in SQL (especially complex querying and indexing), strong foundational knowledge of Object-Oriented Programming (OOP), and hands-on experience with either .NET/C# or JavaScript (specifically asynchronous programming).
• Must-have problem-solving skills – Demonstrated ability to pass rigorous Data Structures and Algorithms assessments (Leetcode easy/medium) and design logical RESTful APIs.
• Nice-to-have skills – Experience with DevOps principles, CI/CD pipelines, cloud infrastructure (Azure/AWS), and a background in SaaS or financial technology (FinTech).
• Experience level – Typically requires a Bachelor's degree in Computer Science or a related field, with experience ranging from strong entry-level candidates to mid-level engineers, depending on the specific team's needs.
• Soft skills – Excellent communication skills, the ability to advocate for your technical decisions, and the patience to navigate complex, sometimes ambiguous interview scenarios and organizational processes.

8. Frequently Asked Questions

Q: How difficult is the Karat technical interview? The Karat interview is generally considered to be of average difficulty, consisting of Leetcode easy to medium questions. The real challenge is the pace; you are expected to complete up to three questions in 45 minutes, meaning you must write working code quickly and efficiently.

Q: Why does AvidXchange outsource their initial technical screen? Outsourcing to Karat allows AvidXchange to standardize the technical evaluation process, ensuring every candidate is tested on a baseline of algorithmic and API design skills before utilizing internal engineering hours. It is by design highly scripted and objective.

Q: I haven't heard back from the recruiter after my interview. Is this normal? Unfortunately, candidates frequently report communication delays or "ghosting" from the recruiting team. This is often due to high application volumes. It is highly recommended to follow up politely but persistently if you do not hear back within a week of your interview.

Q: Will the final rounds involve live coding? Yes, the final rounds with AvidXchange engineers typically include a live coding or screen-sharing component. This is often focused heavily on SQL (such as writing queries under specific constraints) rather than algorithmic puzzles.

Q: Do I need extensive FinTech experience to be hired? While having a background in FinTech or B2B SaaS is a strong nice-to-have, it is not strictly required. AvidXchange is primarily looking for strong software engineering fundamentals, though you should make an effort to understand their business model before the interview.

9. Other General Tips

• Master the "No Aggregate" SQL Constraint: Prepare specifically for the common AvidXchange technical test where you must write complex SQL queries without using standard aggregate functions. Brush up on self-joins and subqueries.
• Drive the Karat API Questions: The API design questions in the Karat round can sometimes feel poorly constructed or lacking context. Do not guess; actively ask the interviewer clarifying questions to define the scope before you start answering.
• Prepare Your "Why AvidXchange?" Narrative: The initial HR screen will heavily focus on your motivations. Have a clear, articulate answer ready that demonstrates you understand their position in the B2B payment automation space.
• Speak to DevOps and Full Lifecycle: AvidXchange values engineers who understand what happens to their code after it is merged. Be prepared to discuss CI/CD, deployment strategies, and basic infrastructure concepts.
• Manage Your Expectations on Communication: Go into the process knowing that recruiter communication might be slow. Do not let a lack of immediate feedback discourage you; stay professional and follow up on your own timeline.

10. Summary & Next Steps

Securing a Software Engineer role at AvidXchange is an opportunity to build mission-critical software that drives the financial operations of countless businesses. The interview process is rigorous and multi-faceted, requiring you to pivot from the rapid-fire algorithmic problem-solving of the Karat interview to deep, nuanced discussions about SQL, .NET, and system architecture with internal engineering teams.

This compensation data provides a baseline expectation for the role. Keep in mind that actual offers will vary based on your specific experience level, your performance during the technical rounds, and your location. Use this information to anchor your expectations and prepare for future negotiation conversations.

By focusing your preparation on the specific constraints of the process—mastering Graph/DFS algorithms, practicing complex SQL queries without aggregate functions, and refining your system design communication—you will position yourself as a highly competitive candidate. Approach the process with patience, confidence, and a clear understanding of the value you can bring to their engineering organization. For more insights, practice scenarios, and peer experiences, continue exploring resources on Dataford to ensure you are fully prepared for interview day. You have the skills to succeed; now it is time to execute.