athenahealth Software Engineer Interview Guide

The 60-second brief

As a Software Engineer at athenahealth, you play a central role in delivering cloud-based software solutions that power the healthcare ecosystem across the United States. Your work directly impacts millions of patients, healthcare providers, and administrative staff by driving clinical productivity, streamlining revenue cycle management, and improving patient outcomes. Whether you are modernizing core enterprise applications like athenaCollector and athenaClinicals, building greenfield features in the Patient Experience (PEX) division, or scaling internal developer platforms, you are building technology where reliability, compliance, and performance are paramount. The engineering challenge at athenahealth is a compelling blend of maintaining mission-critical, high-throughput healthcare infrastructure while continuously migrating toward modern distributed architectures.

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

Focus areas

• DSA (Data Structures and Algorithms)
• Coding Interviews
• Software Engineering Interview Process

The athenahealth interview process

athenahealth candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Recruiter Phone Screen

Initial call focusing on your background, technical interests, and alignment with open team roles.

What to demonstrate

• Initial call focusing on your background, technical interests, and alignment with open team roles
• Depth in DSA (Data Structures and Algorithms)

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.

Online Coding Assessment

Automated coding assessment or a live technical screening call where you solve coding problems.

What to demonstrate

• Automated coding assessment or a live technical screening call where you solve coding problems
• Depth in DSA (Data Structures and Algorithms)

How to prepare

• Answer aloud and timed: Implement an efficient string reversal algorithm without using built-in library functions, and discuss time/space complexity optimizations.
• Answer aloud and timed: Write a program to merge two sorted arrays without extra space where possible, optimizing for minimal operations.

Technical Interview Loop

Comprehensive interview loop with multiple technical sessions covering coding, design, and behavioral aspects.

What to demonstrate

• Comprehensive interview loop with multiple technical sessions covering coding, design, and behavioral aspects
• Depth in DSA (Data Structures and Algorithms)

How to prepare

• Answer aloud and timed: Given a two-dimensional grid representing a puzzle, implement a function that simulates gravity when specific elements are removed.
• Answer aloud and timed: Design an online ticketing and reservation system (e.g., a movie theater booking platform), focusing on low-level class design, concurrency, and seat locking mechanisms.

Where candidates lose points

Clarify constraints before writing code

Always take the first 3–5 minutes of a technical problem to discuss input sizes, boundary conditions, expected edge cases, and time/space complexity goals with your interviewer before writing any solution.

Practice explaining code out loud

Practice writing code while explaining your thought process simultaneously. Interviewers evaluate your approach, reasoning, and clarity of communication as much as your final working code.

Be receptive to interviewer hints

If an interviewer interrupts or suggests considering a specific edge case, treat it as a collaborative nudge. Incorporate their feedback constructively rather than defensively.

Questions & practice

Given an array of integers, find the minimum sum of all possible subsets such that this minimum sum is not pre

Medium · Data Structures & Algorithms

Given an array of integers, find the minimum sum of all possible subsets such that this minimum sum is not present in the original array.

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, check if it is sorted. If it is not sorted, determine whether swapping at most one pair of ele

Medium · Data Structures & Algorithms

Given an array, check if it is sorted. If it is not sorted, determine whether swapping at most one pair of elements can make it sorted.

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 an efficient string reversal algorithm without using built-in library functions, and discuss time/sp

Medium · Data Structures & Algorithms

Implement an efficient string reversal algorithm without using built-in library functions, and discuss time/space complexity optimizations.

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?

Write a program to merge two sorted arrays without extra space where possible, optimizing for minimal operatio

Medium · Data Structures & Algorithms

Write a program to merge two sorted arrays without extra space where possible, optimizing for minimal operations.

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 a two-dimensional grid representing a puzzle, implement a function that simulates gravity when specific

Medium · Data Structures & Algorithms

Given a two-dimensional grid representing a puzzle, implement a function that simulates gravity when specific elements are removed.

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?

What is the difference between volatile variables and AtomicInteger in Java concurrent programming, and wh

Medium · Core Technical & Stack Mechanics

What is the difference between volatile variables and AtomicInteger in Java concurrent programming, and when would you use each?

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Explain how to make a class completely immutable in Java or TypeScript, and explain why immutability is benefi

Medium · Core Technical & Stack Mechanics

Explain how to make a class completely immutable in Java or TypeScript, and explain why immutability is beneficial in multi-threaded applications.

Approach

1. Say what the runtime actually does before reasoning about the code.
2. Name what is shared across threads and what owns each piece of state.
3. Identify the window where an invariant is briefly untrue.
4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

• What happens if two callers reach this at the same time?
• Where could this allocate more than you expect?

Write a SQL query utilizing GROUP BY, HAVING, and aggregate functions to extract filtered transaction metr

Medium · Core Technical & Stack Mechanics

Write a SQL query utilizing GROUP BY, HAVING, and aggregate functions to extract filtered transaction metrics from a database table.

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?

Keep soft-deleted accounts from blocking re-registration

Easy · soft delete · unique constraints · engine differences

app_user holds user_id, tenant_id, email CITEXT, password_hash (NULL for SSO principals), email_verified_at, auth_version, status ('invited','active','suspended','deactivated'), created_at, updated_at, deleted_at. Two live accounts for one address inside a tenant must be impossible, but an address freed by a soft delete must be reusable, and the same tenant may delete and re-register it repeatedly. Write the uniqueness DDL for PostgreSQL 16, then the equivalent for MySQL 8 where partial indexes do not exist, and say what each permits once three deleted rows already hold that address.

Approach

1. Start from what is actually unique: not (tenant_id, email), but (tenant_id, email) among live rows. PostgreSQL says that directly — CREATE UNIQUE INDEX app_user_live_email ON app_user (tenant_id, email) WHERE deleted_at IS NULL. A full constraint over the same two columns burns the address permanently the first time someone deletes an account.
2. Keep case-insensitivity in the type or the index, never in the application: CITEXT as given, or UNIQUE (tenant_id, lower(email)) as an expression index where the extension is unavailable. A case-sensitive unique column is exactly how two accounts for one human appear.
3. For MySQL 8 the predicate has to move inside the key: add a discriminator column that is a constant 0 while the row is live and is set to user_id on delete, with UNIQUE (tenant_id, email, deleted_marker). Live rows share the constant and still collide; deleted rows differ from each other and stop colliding.
4. State the NULL variant and its dependency: leaving the marker NULL for deleted rows also works, because a unique index treats NULLs as distinct — true in MySQL, and true in PostgreSQL only under the default NULLS DISTINCT, which PostgreSQL 15 lets you reverse. Check the polarity against the three existing deleted rows: constant-on-live is what preserves the collision you want, and reversing it silently admits duplicate live accounts.

Follow-up

• A deleted account re-registers with the same address the next day. Do the old resource rows follow the new user_id, and how does the API keep the two principals apart?
• How do you honour an erasure request while resource_revision.actor_user_id still references this table?

Design an online ticketing and reservation system (e.g., a movie theater booking platform), focusing on low-le

Medium · System Design & Architecture

Design an online ticketing and reservation system (e.g., a movie theater booking platform), focusing on low-level class design, concurrency, and seat locking mechanisms.

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?

Design a Rate Limiting system to protect API endpoints from excessive traffic, and defend your choice between

Medium · System Design & Architecture

Design a Rate Limiting system to protect API endpoints from excessive traffic, and defend your choice between gateway-level enforcement and application middleware.

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?

How would you design a calendar and appointment scheduling service for medical practices that handles overlapp

Medium · System Design & Architecture

How would you design a calendar and appointment scheduling service for medical practices that handles overlapping provider availability and patient notifications?

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?

Walk through the architecture of an e-commerce catalog and inventory system. How do you decide whether busines

Medium · System Design & Architecture

Walk through the architecture of an e-commerce catalog and inventory system. How do you decide whether business logic belongs in the database tier or microservices layer?

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?

Explain how you would design a secure, high-availability patient messaging platform supporting multiple channe

Medium · System Design & Architecture

Explain how you would design a secure, high-availability patient messaging platform supporting multiple channels like SMS, secure web chat, and push notifications.

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?

Explain the internal working mechanism of a Java HashMap, including hashing collision resolution, load factors

Medium · Core Technical & Stack Mechanics

Explain the internal working mechanism of a Java HashMap, including hashing collision resolution, load factors, and performance changes in modern JDK versions.

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?

Explain the security differences between CSRF protection mechanisms and HTTPS/TLS encryption, and clarify why

Medium · Core Technical & Stack Mechanics

Explain the security differences between CSRF protection mechanisms and HTTPS/TLS encryption, and clarify why transport encryption alone does not prevent request forgery.

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?

Edge instances grow 400 MB per hour until the nightly restart

Hard · memory leak · heap analysis · metric cardinality

Edge API instances start at 700 MB resident and grow about 400 MB/hour; a nightly rolling restart has hidden it for weeks. Growth continues unchanged when request rate halves overnight, p99 degrades in the last hours before an instance is recycled, and heap used immediately after a forced full GC rises monotonically. The service holds no product state. Name the discriminating measurement that separates the plausible causes, give the most likely cause, and give the fix and how you would verify it.

Approach

1. Separate resident memory from live heap first, because they fail differently. Resident size can grow from fragmentation, native buffers or thread stacks while the heap is flat; heap used after a full GC rising monotonically is the measurement that says objects are reachable and not being released. You already have it, so this is retention, not fragmentation, and that closes off half the candidate list.
2. Use the rate's independence from traffic as the discriminator. Growth that continues at half the request rate rules out per-request objects that are merely slow to collect and points at a structure that grows with distinct values observed rather than with call volume. Write the candidates that have that property: a metrics registry keyed on a high-cardinality label, an unevicted cache, an interner, a per-key lock map.
3. Take two heap snapshots an hour apart and diff by retained size, reading the dominator tree, not by allocation count or instance count. Expect one root holding a map with millions of entries, then follow the reference chain to the code that inserts and never removes. Allocation profilers point at churn, which is the wrong signal here.
4. The candidate that fits this service is an observability label carrying an identifier, such as a request path recorded before templating so that /v1/resources/48213 becomes its own metric series. That grows with distinct ids seen, is independent of rate, and explains the late p99 degradation, since GC cost rises with the size of the live set.

Follow-up

• Post-GC heap is now flat but resident size still creeps. What are you looking at, and does it matter?
• How would you have detected this before an OOM, given the nightly restart masked the trend?

Suggested practice checklist

Built from the rounds and topics athenahealth candidates report.

Day 1 — Map the athenahealth loop

• Write out the reported sequence: Recruiter Phone Screen, Online Coding Assessment, Technical Interview Loop.
• 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.

Day 2 — Work DSA (Data Structures and Algorithms)

• Spend the session on DSA (Data Structures and Algorithms), which athenahealth candidates report being tested on.
• Write one worked example in DSA (Data Structures and Algorithms) and time yourself on it.

Deliverable: One timed worked example in DSA (Data Structures and Algorithms).

Day 3 — Work Coding Interviews

• Spend the session on Coding Interviews, which athenahealth 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.

Day 4 — Work Software Engineering Interview Process

• Spend the session on Software Engineering Interview Process, which athenahealth candidates report being tested on.
• Write one worked example in Software Engineering Interview Process and time yourself on it.

Deliverable: One timed worked example in Software Engineering Interview Process.

Day 5 — Answer out loud: Data Structures & Algorithms

• Answer aloud, timed: Given an array of integers, find the minimum sum of all possible subsets such that this minimum sum is not present in the original array.
• Answer aloud, timed: Given an array, check if it is sorted. If it is not sorted, determine whether swapping at most one pair of elements can make it sorted.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms question(s), under time.

Day 6 — Answer out loud: System Design & Architecture

• Answer aloud, timed: Design an online ticketing and reservation system (e.g., a movie theater booking platform), focusing on low-level class design, concurrency, and seat locking mechanisms.
• Answer aloud, timed: Design a Rate Limiting system to protect API endpoints from excessive traffic, and defend your choice between gateway-level enforcement and application middleware.

Deliverable: Spoken answers to 2 reported System Design & Architecture question(s), under time.

Day 7 — Answer out loud: Core Technical & Stack Mechanics

• Answer aloud, timed: Explain the internal working mechanism of a Java HashMap, including hashing collision resolution, load factors, and performance changes in modern JDK versions.
• Answer aloud, timed: What is the difference between volatile variables and AtomicInteger in Java concurrent programming, and when would you use each?

Deliverable: Spoken answers to 2 reported Core Technical & Stack Mechanics question(s), under time.

Behavioural preparation

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

Describe a challenging bug or performance bottleneck you encountered in a recent project. How did you diagnose

Medium · Behavioral & Leadership

Describe a challenging bug or performance bottleneck you encountered in a recent project. How did you diagnose the issue and verify the fix?

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?

Tell me about a time when you disagreed with a technical design choice made by a senior engineer or teammate.

Medium · Behavioral & Leadership

Tell me about a time when you disagreed with a technical design choice made by a senior engineer or teammate. How did you handle the situation?

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 approach learning a large, complex, or legacy codebase when joining a new project team?

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?

Walk me through a project listed on your resume, detailing your specific technical contributions, the key desi

Medium · Behavioral & Leadership

Walk me through a project listed on your resume, detailing your specific technical contributions, the key design choices you made, and what you would do differently today.

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 situation where project requirements changed significantly mid-sprint. How did you adapt your workf

Medium · Behavioral & Leadership

Describe a situation where project requirements changed significantly mid-sprint. How did you adapt your workflow and keep stakeholders informed?

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?