The role of a Software Engineer at Everlywell is pivotal to the company's mission of empowering individuals to take control of their health. As a Software Engineer, you will be responsible for designing, developing, and maintaining software solutions that support a wide array of health-related products and services. Your work directly impacts the user experience and the overall effectiveness of our digital health platform, contributing to better health outcomes for our customers. In this role, you will collaborate with cross-functional teams, including product managers, designers, and data scientists, to build robust systems that handle sensitive health data securely and efficiently. The complexity of the projects you will tackle, such as integrating third-party APIs or developing machine learning algorithms for personalized health insights, makes this position both challenging and rewarding. You will have the opportunity to drive innovation in a fast-paced environment, making significant contributions to products that genuinely improve people's lives.
Phone Screen
reportedInitial screening call to discuss candidate's background and assess fit for the role.
What to demonstrate
- Initial screening call to discuss candidate's background and assess fit for the role
- Depth in Coding Interviews
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 Assessments
reportedCandidates complete coding challenges and technical assessments to evaluate problem-solving abilities.
What to demonstrate
- Candidates complete coding challenges and technical assessments to evaluate problem-solving abilities
- Depth in Coding Interviews
How to prepare
- Answer aloud and timed: Describe a time when you had to learn a new technology quickly. How did you approach it?
- Answer aloud and timed: What is your experience with cloud infrastructure, and how have you utilized it in your work?
In-Person Interviews
reportedInterviews with various team members, including product managers and senior engineers, to assess collaboration and cultural fit.
What to demonstrate
- Interviews with various team members
- Including product managers and senior engineers, to assess collaboration and cultural fit
How to prepare
- Answer aloud and timed: How do you ensure the security and privacy of user data in your applications?
- Answer aloud and timed: Write a function that reverses a string. What is its time complexity?
PracHub editorial advice for the preparation topics above.
Prepare for technical challenges
Practice coding problems on platforms like LeetCode or HackerRank to sharpen your skills.
Research the company
Familiarize yourself with Everlywell's products, culture, and mission to demonstrate your alignment during interviews.
Use the STAR method
When answering behavioral questions, structure your responses using the Situation, Task, Action, Result format for clarity and impact.
Ask insightful questions
Prepare thoughtful questions for your interviewers to show your interest in the role and company.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function that reverses a string. What is its time complexity?
Write a function that reverses a string. What is its time complexity?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
How would you implement a hash table? Explain the operations involved.
How would you implement a hash table? Explain the operations involved.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 a list of numbers, find the two numbers that add up to a specific target.
Given a list of numbers, find the two numbers that add up to a specific target.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 optimize a slow-running algorithm.
Describe how you would optimize a slow-running algorithm.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 binary search algorithm and discuss its efficiency.
Implement a binary search algorithm and discuss its efficiency.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Hold a per-tenant active cap against concurrent creates
A tenant on the standard plan may hold at most 50 resources with status='active'. The create handler runs SELECT count(*) FROM resource WHERE tenant_id = $1 AND status = 'active', compares to 50, then inserts. Two creates arrive 3 ms apart on different instances and the tenant lands at 51. Name the anomaly, say whether PostgreSQL 16 READ COMMITTED or REPEATABLE READ prevents it and why, then give an implementation that holds the cap at READ COMMITTED with the exact statements. Finally, say what changes when the cap is 'at most one running export per tenant' on job_run.
Approach
- Name it: write skew. The two transactions read an overlapping set and write disjoint rows, so there is no row-level conflict for the engine to detect and each commit is individually legal.
- Rule out the levels precisely. READ COMMITTED takes a fresh snapshot per statement and takes no lock on the counted rows, so both see 49. PostgreSQL's REPEATABLE READ is snapshot isolation: it removes non-repeatable reads and phantoms within the snapshot but still admits write skew, because the anomaly is not a re-read of a changed row, it is a read of a set that a concurrent transaction invalidates. Only SERIALIZABLE closes it, by tracking the read dependency and aborting one transaction with SQLSTATE 40001 — a guarantee that exists only if the application re-runs the whole transaction from the read.
- Convert the set predicate into a single-row conflict: keep tenant.active_resource_count and run UPDATE tenant SET active_resource_count = active_resource_count + 1 WHERE tenant_id = $1 AND active_resource_count < 50 in the same transaction as the INSERT. Zero affected rows is the cap, returned as 409. The row lock serialises the decision at any isolation level, and contention is bounded to one tenant's row — which is also the fair-scheduling unit, unlike a global counter that would convoy every tenant behind one row.
- State the cost you just took on: a counter is a second source of truth that can drift, so every path that changes status must adjust it inside the same transaction, and a periodic reconciliation has to exist, with resource_revision as the authority for what the count should have been.
Follow-up
- A resource moves from archived back to active. Which statements change, and what breaks if the counter update and the status change land in different transactions?
- The cap becomes plan-dependent and a plan can change mid-month. Where does the number 50 live, and who reads it?
Write the update path that detects a concurrent edit
resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.
Approach
- One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
- Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
- State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
- Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.
Follow-up
- A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
- Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?
What programming languages are you proficient in, and how have you used them in past projects?
What programming languages are you proficient in, and how have you used them in past projects?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- 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 do you ensure the security and privacy of user data in your applications?
How do you ensure the security and privacy of user data in your applications?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Given a project with tight deadlines, how would you manage your time and resources?
Given a project with tight deadlines, how would you manage your time and resources?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- 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 a complex project you worked on. What were the challenges, and how did you overcome them?
Describe a complex project you worked on. What were the challenges, and how did you overcome them?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- 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 designing a new feature for our health platform?
How would you approach designing a new feature for our health platform?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What metrics would you consider important for measuring the success of a new software release?
What metrics would you consider important for measuring the success of a new software release?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Discuss a technical challenge you encountered and the steps you took to resolve it.
Discuss a technical challenge you encountered and the steps you took to resolve it.
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- 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 design a system for handling user authentication in a health application?
How would you design a system for handling user authentication in a health application?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
Describe the architecture you would implement for a data-driven application.
Describe the architecture you would implement for a data-driven application.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
What considerations would you keep in mind when designing a microservices architecture?
What considerations would you keep in mind when designing a microservices architecture?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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 do you approach scalability in your software designs?
How do you approach scalability in your software designs?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
Explain how you would ensure high availability in a critical system.
Explain how you would ensure high availability in a critical system.
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- 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?
Can you explain how you approach debugging a complex issue?
Can you explain how you approach debugging a complex issue?
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- 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?
Built from the rounds and topics Everlywell candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Everlywell loop
- Write out the reported sequence: Phone Screen, Technical Assessments, In-Person Interviews.
- 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 3 reported rounds, with the weakest marked.
02Work Coding Interviews
- Spend the session on Coding Interviews, which Everlywell candidates report being tested on.
- Write one worked example in Coding Interviews and time yourself on it.
Deliverable: One timed worked example in Coding Interviews.
03Work Technical Interviewing
- Spend the session on Technical Interviewing, which Everlywell candidates report being tested on.
- Write one worked example in Technical Interviewing and time yourself on it.
Deliverable: One timed worked example in Technical Interviewing.
04Work Practical Coding Challenge / Take-home Style Project
- Spend the session on Practical Coding Challenge / Take-home Style Project, which Everlywell candidates report being tested on.
- Write one worked example in Practical Coding Challenge / Take-home Style Project and time yourself on it.
Deliverable: One timed worked example in Practical Coding Challenge / Take-home Style Project.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: What programming languages are you proficient in, and how have you used them in past projects?
- Answer aloud, timed: Can you explain how you approach debugging a complex issue?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Coding / Algorithms
- Answer aloud, timed: Write a function that reverses a string. What is its time complexity?
- Answer aloud, timed: How would you implement a hash table? Explain the operations involved.
Deliverable: Spoken answers to 2 reported Coding / Algorithms question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a situation where you faced conflict within your team. How did you resolve it?
- Answer aloud, timed: What motivates you to perform at your best?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
Describe a time when you had to learn a new technology quickly. How did you approach it?
Describe a time when you had to learn a new technology quickly. How did you approach it?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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?
What is your experience with cloud infrastructure, and how have you utilized it in your work?
What is your experience with cloud infrastructure, and how have you utilized it in your work?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 situation where you faced conflict within your team. How did you resolve it?
Describe a situation where you faced conflict within your team. How did you resolve it?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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?
What motivates you to perform at your best?
What motivates you to perform at your best?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 your tasks when working on multiple projects?
How do you prioritize your tasks when working on multiple projects?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 time when you took the initiative to improve a process or product.
Describe a time when you took the initiative to improve a process or product.
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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 handle feedback and criticism of your work?
How do you handle feedback and criticism of your work?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- 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?
- 01
Describe a time when you had to learn a new technology quickly. How did you approach it?
- 02
What is your experience with cloud infrastructure, and how have you utilized it in your work?
- 03
Describe a situation where you faced conflict within your team. How did you resolve it?
- 04
What motivates you to perform at your best?
How difficult are the interviews, and how much preparation time is typical?
The interviews can be challenging, particularly the technical components. Candidates typically spend several weeks preparing, focusing on coding algorithms, system design, and behavioral questions.
Everlywell Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate a strong technical background, problem-solving skills, and a clear cultural fit with Everlywell's values. They effectively communicate their thought processes and show enthusiasm for the role.
Everlywell Software Engineer candidate reports ↗What is the culture like at Everlywell?
Everlywell fosters a collaborative, innovative environment where employees are encouraged to take ownership of their work and contribute to the company’s mission.
Everlywell Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
The timeline can vary, but candidates usually receive feedback within a few weeks after the final interview.
Everlywell Software Engineer candidate reports ↗Are there remote work options available?
Everlywell supports flexible work arrangements, including remote work opportunities, depending on the role and team dynamics.
Everlywell Software Engineer candidate reports ↗What topics does Everlywell test in interviews?
Everlywell interviews most often cover Stakeholder Management, Interview Communication, Problem Solving, Communication Clarity, and Cross-Functional Collaboration. The exact emphasis depends on the specific role you apply for.
Everlywell Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01Everlywell Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
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