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Highmark Health Software Engineer Interview Guide

Highmark Health Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

As a Software Engineer at Highmark Health, you sit at the intersection of technology and healthcare innovation. Highmark Health is a massive, diversified healthcare partner that operates both health insurance plans and clinical care delivery networks. In this role, your code directly impacts millions of members and patients, ensuring they have seamless, reliable access to critical healthcare services, digital wellness tools, and secure insurance portals. The software engineering team is responsible for building, scaling, and maintaining the vital digital infrastructure that connects patients, clinical providers, and insurance administrators. Whether you are working on modernizing legacy insurance systems, developing patient-facing mobile and web applications, or integrating enterprise platforms like Pega, your work directly influences operational efficiency and patient outcomes.

This guide is scoped to a Software Engineer candidate at Highmark Health.

Focus areas

  • Behavioral Interviewing
  • Java
  • Object-Oriented Programming (OOP)

The Highmark Health interview process

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

Phone Screen

Complete a phone screen with a recruiter to discuss your resume, background, location preferences, and basic skills alignment.

What to demonstrate

  • Complete a phone screen with a recruiter to discuss your resume, background, location preferences, and basic skills alignment
  • Depth in Behavioral Interviewing

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.

Hiring Manager Interview

Have a video or phone interview with the hiring manager to dive deeper into your technical experience, project history, and domain knowledge.

What to demonstrate

  • Have a video or phone interview with the hiring manager to dive deeper into your technical experience, project history, and domain knowledge
  • Depth in Behavioral Interviewing

How to prepare

  • Prepare two projects you led end to end, each with the decision you owned and what it cost.
  • Have three questions about the team's roadmap and how success is measured in the first six months.

Team Interview

Participate in a structured team interview, typically a panel of five to six people, focusing on technical fundamentals, domain skills, and behavioral questions.

What to demonstrate

  • Participate in a structured team interview, typically a panel of five to six people
  • Focusing on technical fundamentals, domain skills, and behavioral questions

How to prepare

  • Answer aloud and timed: What is the difference between a checked exception and an unchecked exception?
  • Answer aloud and timed: How do you optimize a slow-running SQL query?

Where candidates lose points

Master the STAR Method

Do not generalize your achievements. Be highly specific about what you did in past projects. Use numbers and clear outcomes to demonstrate your impact.

Showcase Adaptability

Highmark Health frequently cross-trains engineers on enterprise platforms like Pega. Emphasize your ability to pick up new tools, languages, and frameworks quickly and enthusiastically.

Highmark Health puts a massive emphasis on teamwork and interpersonal skills

Showing that you are easy to work with, humble, and a strong communicator can carry just as much weight as your technical background.

Questions & practice

How does garbage collection work in Java, and what are some ways to prevent memory leaks?

Medium · Object-Oriented Programming & Java

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?

Track a rolling failure rate per destination for circuit decisions

Easy · sliding window · ring buffer · circuit breaker

The egress service delivers about 1,500 webhooks per second across roughly 40,000 destinations, each call bounded by a 10 second timeout. Maintain, per destination, the failure rate over the trailing 60 seconds so a caller can ask before dispatch whether the circuit should open. Attempts arrive as (destination_id, finished_at_ms, outcome). Requirement: amortised O(1) per attempt, with total memory bounded by the destination count rather than by traffic. Give the structure, its exact memory, and the rule that stops a destination with three attempts from opening a circuit.

Approach

  1. Name the exact-deque version and then reject it as the default. Holding timestamps and advancing a tail pointer past anything older than now minus 60 seconds is a correct two-pointer window at amortised O(1) per attempt, but its memory tracks in-window traffic, so one destination in a retry storm holds hundreds of thousands of entries while thousands of quiet destinations hold none.
  2. Use a ring of 60 one-second buckets per destination, each bucket a pair of counters for attempts and failures. On an attempt, advance the ring by the elapsed whole seconds, zeroing at most min(elapsed, 60) buckets, then increment the head. That is amortised O(1) with a fixed footprint per destination.
  3. State the footprint: 60 buckets times two 4-byte counters is 480 bytes of payload per destination, so 40,000 destinations is roughly 20 to 25 MB with per-entry overhead, bounded by the catalogue rather than by the rate. The cost is granularity, since the oldest bucket ages out in whole seconds, which is far tighter than the decision needs.
  4. Require a minimum sample before the circuit may open. A destination with three attempts and three failures reads as 100 percent and is not evidence; a floor of roughly 20 attempts in the window makes the ratio meaningful, and below that floor use a run of consecutive failures as the trigger instead.

Follow-up

  • The fleet is 30 instances and each sees roughly a thirtieth of a destination's traffic. Where does the rate actually live, and what does a per-instance answer get wrong?
  • A destination answers in 9.5 seconds and succeeds. It is not failing but it is consuming your per-destination concurrency. What signal should open the circuit here?

Diff a projection against the primary without per-row point reads

Hard · reconciliation · range hashing · throttling

The listing projection has drifted and some rows show a stale version. The primary holds 40,000,000 resource rows across 12,000 tenants while serving 1,200 writes and 14,000 reads per second. The obvious repair, reading each resource row and comparing its version against the projection, is correct and would eventually finish. Explain precisely why it is unacceptable here, then give a diff that finds the differing rows, state its complexity, and make it safe to run against a live primary. Replication lag is usually under 100 ms and is not bounded.

Approach

  1. Quantify the naive cost rather than calling it slow: 40,000,000 point reads at even 0.5 ms each is over five hours serialised, and the only lever is concurrency, which is exactly what you cannot spend. The primary's pool is sized for the write path, and 40,000,000 random reads evict the buffer cache that sustains the 85 percent cache hit rate, so the audit degrades the system it is auditing.
  2. Replace random access with one ordered pass per side. Both sides can be read in (tenant_id, resource_id) order, which is a sequential scan on each and a merge join in O(n) time and O(1) memory. For a dense diff that is the whole answer, and it reads the primary once instead of 40,000,000 times.
  3. For the expected sparse case, compare range hashes instead of rows: partition the key space, compute per range an order-independent aggregate over hash(resource_id, version), compare aggregates, and descend only into ranges that differ. With d differing rows and branching factor B, at most d ranges mismatch per level, so the drill-down examines O(d log_B(n/d)) ranges and reads full rows only in mismatching leaves.
  4. Aggregate with a sum modulo 2^64 or a multiset hash, never XOR. XOR is order-independent but self-cancelling, so two rows wrong in the same way, or a row duplicated on one side, leave the range aggregate matching and the range is declared clean.

Follow-up

  • The diff reports 900 stale rows. How do you decide between patching those rows and rebuilding the projection from resource_revision?
  • Same job, but the projection lives in a search index that cannot be scanned in key order. What changes?

How do you optimize a slow-running SQL query?

Medium · Data & Database Management

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 differences between an inner join, left join, and outer join.

Medium · Data & Database Management

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?

What are database indexes, and how do they improve query performance? What are the trade-offs of using them?

Medium · Data & Database Management

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?

What is database normalization, and what are the benefits of reaching the third normal form (3NF)?

Medium · Data & Database Management

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 four pillars of Object-Oriented Programming (OOP) and how you have applied them in a recent projec

Medium · Object-Oriented Programming & Java

Explain the four pillars of Object-Oriented Programming (OOP) and how you have applied them in a recent project.

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?

What is the difference between an abstract class and an interface in Java? When would you use one over the oth

Medium · Object-Oriented Programming & Java

What is the difference between an abstract class and an interface in Java? When would you use one over the other?

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 concept of method overloading versus method overriding.

Medium · Object-Oriented Programming & Java

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?

What is the difference between a checked exception and an unchecked exception?

Medium · Object-Oriented Programming & Java

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 design a database schema to track patient appointments and insurance claims?

Medium · Data & Database Management

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?

If you were assigned to a team using a technology you have no experience with (such as Pega), how would you st

Medium · Scenario-Based & System Support

If you were assigned to a team using a technology you have no experience with (such as Pega), how would you structure your first 30 days to get up to speed?

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?

Why do you want to work as a Software Engineer in the healthcare industry, and how does your background align

Medium · Scenario-Based & System Support

Why do you want to work as a Software Engineer in the healthcare industry, and how does your background align with this mission?

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?

Highmark Health operates 24/7/365 systems. How do you approach on-call support or handling a critical producti

Medium · Scenario-Based & System Support

Highmark Health operates 24/7/365 systems. How do you approach on-call support or handling a critical production outage under pressure?

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 Highmark Health candidates report.

Day 1 — Map the Highmark Health loop

  • Write out the reported sequence: Phone Screen, Hiring Manager Interview, Team Interview.
  • 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 Behavioral Interviewing

  • Spend the session on Behavioral Interviewing, which Highmark Health candidates report being tested on.
  • Write one worked example in Behavioral Interviewing and time yourself on it.

Deliverable: One timed worked example in Behavioral Interviewing.

Day 3 — Work Java

  • Spend the session on Java, which Highmark Health candidates report being tested on.
  • Write one worked example in Java and time yourself on it.

Deliverable: One timed worked example in Java.

Day 4 — Work Object-Oriented Programming (OOP)

  • Spend the session on Object-Oriented Programming (OOP), which Highmark Health candidates report being tested on.
  • Write one worked example in Object-Oriented Programming (OOP) and time yourself on it.

Deliverable: One timed worked example in Object-Oriented Programming (OOP).

Day 5 — Answer out loud: Object-Oriented Programming & Java

  • Answer aloud, timed: Explain the four pillars of Object-Oriented Programming (OOP) and how you have applied them in a recent project.
  • Answer aloud, timed: What is the difference between an abstract class and an interface in Java? When would you use one over the other?

Deliverable: Spoken answers to 2 reported Object-Oriented Programming & Java question(s), under time.

Day 6 — Answer out loud: Data & Database Management

  • Answer aloud, timed: How do you optimize a slow-running SQL query?
  • Answer aloud, timed: Explain the differences between an inner join, left join, and outer join.

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

Day 7 — Answer out loud: Behavioral & Team Collaboration (STAR Method)

  • Answer aloud, timed: Describe a time when you had to work with a difficult team member on a group project. How did you handle the situation, and what was the outcome?
  • Answer aloud, timed: Tell me about a time you had to learn a new technology or programming language quickly to complete a project.

Deliverable: Spoken answers to 2 reported Behavioral & Team Collaboration (STAR Method) question(s), under time.

Behavioural preparation

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

Describe a time when you had to work with a difficult team member on a group project. How did you handle the s

Medium · Behavioral & Team Collaboration (STAR Me

Describe a time when you had to work with a difficult team member on a group project. How did you handle the situation, and what was the outcome?

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 you had to learn a new technology or programming language quickly to complete a project.

Medium · Behavioral & Team Collaboration (STAR Me

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?

Recall a project where the requirements changed mid-cycle. How did you adapt, and how did you ensure the proje

Medium · Behavioral & Team Collaboration (STAR Me

Recall a project where the requirements changed mid-cycle. How did you adapt, and how did you ensure the project was delivered successfully?

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 you disagreed with a technical decision made by a lead or manager. How did you present yo

Medium · Behavioral & Team Collaboration (STAR Me

Tell me about a time you disagreed with a technical decision made by a lead or manager. How did you present your perspective?

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 you had to manage multiple competing priorities. How did you decide what to focus o

Medium · Behavioral & Team Collaboration (STAR Me

Describe a situation where you had to manage multiple competing priorities. How did you decide what to focus on first?

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?