Facet Software Engineer Interview Guide

The 60-second brief

As a Software Engineer at Facet, you will play a pivotal role in shaping the future of financial literacy tools that empower users to make informed decisions. This position is integral to the development and enhancement of products that aim to simplify complex financial concepts, making them accessible to a wider audience. You will work collaboratively with cross-functional teams to translate user needs into elegant, efficient software solutions that drive the business forward. The role involves deep engagement with product teams, where your contributions will directly impact user experience and product functionality. Expect to tackle challenges that require innovative thinking and technical expertise, ranging from backend systems to user-facing applications.

This guide is scoped to a Software Engineer candidate at Facet.

Focus areas

• Frontend Development (React)
• React (JSX/Props/Attributes)
• System Design (Frontend-focused)

The Facet interview process

Facet candidates report 5 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Phone Screen

Initial call with a recruiter to evaluate candidate background and role fit.

What to demonstrate

• Initial call with a recruiter to evaluate candidate background and role fit
• Depth in Frontend Development (React)

How to prepare

• Be able to walk your CV end to end in two minutes, and say why this company specifically.
• Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Coding Exercise

Candidates complete a coding exercise to demonstrate technical skills.

What to demonstrate

• Candidates complete a coding exercise to demonstrate technical skills
• Depth in Frontend Development (React)

How to prepare

• Answer aloud and timed: Describe how you would handle a situation where you need to optimize a slow-running query.
• Answer aloud and timed: Write a function to reverse a linked list.

Behavioral Interview

Discussion of past experiences and behavioral questions to assess cultural fit.

What to demonstrate

• Discussion of past experiences and behavioral questions to assess cultural fit
• Depth in Frontend Development (React)

How to prepare

• Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
• Re-read the description of the behavioral interview above and write down what you would ask to confirm before it.

System Design Discussion

Candidates engage in a discussion about system design concepts and solutions.

What to demonstrate

• Candidates engage in a discussion about system design concepts and solutions
• Depth in Frontend Development (React)

How to prepare

• Answer aloud and timed: Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?
• Answer aloud and timed: How do you prioritize tasks when working on multiple projects?

Whiteboarding Session

Interactive session where candidates solve problems on a whiteboard.

What to demonstrate

• Interactive session where candidates solve problems on a whiteboard
• Depth in Frontend Development (React)

How to prepare

• Answer aloud and timed: Can you give an example of a time you had to communicate a complex technical concept to a non-technical audience?
• Answer aloud and timed: Design a URL shortening service. What considerations would you take into account?

Where candidates lose points

Be Prepared for Flexibility

Expect that the interview process may evolve, with additional steps or changes based on feedback from the team.

Practice Communication

Clearly articulate your thought process during technical challenges to demonstrate your problem-solving approach.

Research the Company

Familiarize yourself with Facet's products and mission to convey genuine interest and alignment with their goals.

Questions & practice

Write a function to reverse a linked list.

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Given an array of integers, find two numbers such that they add up to a specific target.

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Implement a function to check if a string is a palindrome.

Medium · Coding / Algorithms

Approach

1. Restate the input: its shape, its size, and what is guaranteed about it.
2. Name the brute-force solution and its complexity before improving on it.
3. Choose the data structure from the access pattern, not from familiarity.
4. State the target complexity and say which constraint rules the naive version out.

Follow-up

• How does this change if the input no longer fits in memory?
• What is the worst case, and how likely is it on real data?

Describe how you would handle a situation where you need to optimize a slow-running query.

Medium · Technical / Domain Questions

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. Handle the rows that do not match: that is usually the actual question.

Follow-up

• How does the query change if that join becomes one-to-many?
• What happens to this when the table is ten times larger?

Discuss the trade-offs between SQL and NoSQL databases in a given scenario.

Medium · System Design / Architecture

Approach

1. Name the grain you start from and join outward from it.
2. Check whether any join is one-to-many before aggregating, or the sums inflate.
3. Say which index the query would use, and what makes it unusable.
4. Handle the rows that do not match: that is usually the actual question.

Follow-up

• How does the query change if that join becomes one-to-many?
• What happens to this when the table is ten times larger?

Explain the difference between REST and GraphQL.

Medium · Technical / Domain Questions

Approach

1. Say who the caller is and what they do when the call fails halfway.
2. Define the identity of a request so a retry cannot double-apply it.
3. Separate accepted, pending, failed and confirmed; they are different facts.
4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

• What happens if the caller retries after a timeout?
• How does a client discover it is on an old version of this contract?

Design a URL shortening service. What considerations would you take into account?

Medium · System Design / Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

How would you architect a scalable web application to handle millions of users?

Medium · System Design / Architecture

Approach

1. Fix the scope first: who calls this, how often, and what they do when it fails.
2. Name the read and write paths separately; they rarely have the same bottleneck.
3. Choose a partition key and say what query it makes expensive.
4. State the consistency you need, and where you are willing to be stale.

Follow-up

• What breaks first when traffic grows ten times?
• How does this behave when that dependency is down for an hour?

Given a use case, how would you choose the appropriate technology stack?

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

Describe your process for evaluating and implementing third-party libraries or tools.

Medium · Problem-Solving / Case Studies

Approach

1. Clarify what is being asked and what a complete answer contains.
2. State your assumptions explicitly before working the problem.
3. Say what you would check first and why it is the highest-information step.
4. Work from the requirement backwards to the design.

Follow-up

• What assumption would you test first?
• How would you know your answer was wrong?

How would you approach debugging a production issue in a live application?

Medium · Problem-Solving / Case Studies

Approach

1. Establish what changed and when, before forming any theory.
2. Pick a bisection that eliminates candidates whichever way it turns out.
3. Check the instrumentation before believing the symptom.
4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

• What would you look at first, and what would it rule out?
• How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics Facet candidates report.

Day 1 — Map the Facet loop

• Write out the reported sequence: Phone Screen, Technical Coding Exercise, Behavioral Interview, System Design Discussion, Whiteboarding Session.
• For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 5 reported rounds, with the weakest marked.

Day 2 — Work Frontend Development (React)

• Spend the session on Frontend Development (React), which Facet candidates report being tested on.
• Write one worked example in Frontend Development (React) and time yourself on it.

Deliverable: One timed worked example in Frontend Development (React).

Day 3 — Work React (JSX/Props/Attributes)

• Spend the session on React (JSX/Props/Attributes), which Facet candidates report being tested on.
• Write one worked example in React (JSX/Props/Attributes) and time yourself on it.

Deliverable: One timed worked example in React (JSX/Props/Attributes).

Day 4 — Work System Design (Frontend-focused)

• Spend the session on System Design (Frontend-focused), which Facet candidates report being tested on.
• Write one worked example in System Design (Frontend-focused) and time yourself on it.

Deliverable: One timed worked example in System Design (Frontend-focused).

Day 5 — Answer out loud: Technical / Domain Questions

• Answer aloud, timed: Explain the difference between REST and GraphQL.
• Answer aloud, timed: What is the importance of code reviews in the software development process?

Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.

Day 6 — Answer out loud: Coding / Algorithms

• Answer aloud, timed: Write a function to reverse a linked list.
• Answer aloud, timed: Given an array of integers, find two numbers such that they add up to a specific target.

Deliverable: Spoken answers to 2 reported Coding / Algorithms question(s), under time.

Day 7 — Answer out loud: Behavioral / Leadership

• Answer aloud, timed: Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?
• Answer aloud, timed: How do you prioritize tasks when working on multiple projects?

Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

What is the importance of code reviews in the software development process?

Medium · Technical / Domain Questions

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?

Medium · Behavioral / Leadership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

How do you prioritize tasks when working on multiple projects?

Medium · Behavioral / Leadership

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?

Can you give an example of a time you had to communicate a complex technical concept to a non-technical audien

Medium · Behavioral / Leadership

Can you give an example of a time you had to communicate a complex technical concept to a non-technical audience?

Approach

1. Pick a story where you made the decision, not one where you watched it.
2. State the situation in two sentences and spend the rest on the reasoning.
3. Give the blast radius: what could have broken, and what you measured.
4. Name the disagreement and how you resolved it with evidence.

Follow-up

• What would you do differently if you ran that again?
• How did you know your change caused the improvement?