Johnson Controls · Software Engineer
Updated · 2026-10-02

Johnson Controls Software Engineer
Interview Guide

THE 60-SECOND BRIEF

As a Software Engineer at Johnson Controls, you will write software that bridges the physical and digital worlds. Johnson Controls is a global leader in smart buildings, energy efficiency, industrial refrigeration, and integrated fire and security infrastructure. The software engineering team develops critical platforms that control building automation systems (BAS), manage complex HVAC networks, run modern chillers, and orchestrate smart building IoT ecosystem applications like Metasys. In this role, your code directly influences how large-scale industrial systems, commercial high-rises, and critical facilities operate. You will be responsible for designing and deploying resilient backend microservices, robust firmware, intuitive user interfaces, and embedded control logic.

This guide is scoped to a Software Engineer candidate at Johnson Controls.

Johnson Controls candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Electrical Machines (Induction machine, motors)Transformers (working, types)PLC (Programmable Logic Controller) Fundamentals

22 min read

Browse Software Engineer questions

See the practice prompts

1Candidate experiences ↗Read their reports
25Practice promptsAcross five skill areas

As a Software Engineer at Johnson Controls, you will write software that bridges the physical and digital worlds. Johnson Controls is a global leader in smart buildings, energy efficiency, industrial refrigeration, and integrated fire and security infrastructure. The software engineering team develops critical platforms that control building automation systems (BAS), manage complex HVAC networks, run modern chillers, and orchestrate smart building IoT ecosystem applications like Metasys. In this role, your code directly influences how large-scale industrial systems, commercial high-rises, and critical facilities operate. You will be responsible for designing and deploying resilient backend microservices, robust firmware, intuitive user interfaces, and embedded control logic. Engineers at Johnson Controls work across domain boundaries—collaborating with hardware engineers, systems architects, and field teams—to transition complex physical requirements into high-performing, scalable software solutions. Building software at Johnson Controls means solving challenges around system latency, industrial network protocols, data telemetry, and physical safety standards. Whether you are implementing core algorithms for HVAC optimization, building data pipelines for enterprise energy management, or creating responsive applications for facility operators, your engineering output directly impacts sustainability, energy efficiency, and operational safety globally.

01

Online Screening Assessment

reported

Initial assessment consisting of aptitude and technical quizzes for university hires or coding challenges for experienced roles.

What to demonstrate

  • Initial assessment consisting of aptitude and technical quizzes for university hires or coding challenges for experienced roles
  • Depth in Electrical Machines (Induction machine, motors)

How to prepare

  • Answer aloud and timed: Explain the core principles of Object-Oriented Programming (OOP) and give an example of inheritance versus composition.
  • Answer aloud and timed: What is the difference between var, let, and const in JavaScript, and how does scope work in dynamic languages?
Johnson Controls Software Engineer candidate reports ↗
02

Technical Round 1

reported

Focuses on fundamentals, resume review, and discussion of past projects.

What to demonstrate

  • Focuses on fundamentals, resume review, and discussion of past projects
  • Depth in Electrical Machines (Induction machine, motors)

How to prepare

  • Answer aloud and timed: How do you implement dependency injection in backend frameworks, and what benefits does it bring to testability?
  • Answer aloud and timed: Write a function to reverse a singly linked list and discuss its time and space complexity.
Johnson Controls Software Engineer candidate reports ↗
03

Technical Round 2

reported

Deeper evaluation of system architecture skills, domain-specific knowledge, and coding proficiency.

What to demonstrate

  • Deeper evaluation of system architecture skills, domain-specific knowledge, and coding proficiency
  • Depth in Electrical Machines (Induction machine, motors)

How to prepare

  • Answer aloud and timed: How do you check if two strings are valid anagrams?
  • Answer aloud and timed: What are common design patterns you have implemented in previous projects (e.g., Factory, Singleton, Observer)?
Johnson Controls Software Engineer candidate reports ↗
04

Managerial and HR Round

reported

Discussion of behavioral attributes, salary expectations, and cultural alignment.

What to demonstrate

  • Discussion of behavioral attributes, salary expectations, and cultural alignment
  • Depth in Electrical Machines (Induction machine, motors)

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 managerial and hr round above and write down what you would ask to confirm before it.
Johnson Controls Software Engineer candidate reports ↗

1 candidate reports. Individual accounts describe a particular role and hiring cycle.

Software Engineer

Johnson Controls Software Engineer interview: virtual manager and team

HR Screen → OtherOutcome: offer

After an HR call, I interviewed with the engineering manager. That first conversation was mostly about my experience, and it felt relaxed and fluid. Soon afterward, I met three people from the team in another smooth, conversational interview. Once those rounds were done, I received an offer. Everything happened virtually, with no site visit required, which kept the path straightforward from start…

Read full experience

PracHub editorial advice for the preparation topics above.

01

Prepare clear, structured examples using the STAR method (Situation, Task, Action, Result) for behavioral discussions

Focus heavily on technical decisions, team collaboration, and measurable outcomes.

02

Master your resume projects

Interviewers consistently base questions on your listed experience. Be ready to explain your exact contributions, architectural trade-offs, and technical solutions for every project listed on your resume.

03

Highlight low-level or hardware-adjacent knowledge

If you have experience working with sensors, serial communication, embedded systems, microcontrollers, or multithreaded logic, explicitly highlight these experiences during technical discussions.

04

Emphasize systematically solving problems

When working through coding or system design questions, articulate your reasoning out loud. Interviewers value structured thinking, attention to edge cases, and root-cause analysis skills over speed.

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

21 technical prompts0 include a worked solution

Explain the core principles of Object-Oriented Programming (OOP) and give an example of inheritance versus com

medium
Core Software Engineering & Data Structu

Explain the core principles of Object-Oriented Programming (OOP) and give an example of inheritance versus composition.

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 `var`, `let`, and `const` in JavaScript, and how does scope work in dynamic lan

medium
Core Software Engineering & Data Structu

What is the difference between var, let, and const in JavaScript, and how does scope work in dynamic languages?

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?

How do you implement dependency injection in backend frameworks, and what benefits does it bring to testabilit

medium
Core Software Engineering & Data Structu

How do you implement dependency injection in backend frameworks, and what benefits does it bring to testability?

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 function to reverse a singly linked list and discuss its time and space complexity.

medium
Core Software Engineering & Data Structu

Write a function to reverse a singly linked list and discuss its time and space complexity.

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?

How do you check if two strings are valid anagrams?

medium
Core Software Engineering & Data Structu

How do you check if two strings are valid anagrams?

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 are common design patterns you have implemented in previous projects (e.g., Factory, Singleton, Observer)

medium
Core Software Engineering & Data Structu

What are common design patterns you have implemented in previous projects (e.g., Factory, Singleton, Observer)?

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?

Explain how garbage collection and memory management operate in runtime environments like Java or.NET.

medium
Core Software Engineering & Data Structu

Explain how garbage collection and memory management operate in runtime environments like Java or.NET.

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 the difference between a mutex and a semaphore in an operating system or RTOS environment.

medium
Embedded Systems, Firmware & Hardware In

Explain the difference between a mutex and a semaphore in an operating system or RTOS environment.

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?

How do interrupt service routines (ISRs) function, and what design practices prevent race conditions in hardwa

medium
Embedded Systems, Firmware & Hardware In

How do interrupt service routines (ISRs) function, and what design practices prevent race conditions in hardware-driven software?

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?

Built from the rounds and topics Johnson Controls candidates report.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Map the Johnson Controls loop
  • Write out the reported sequence: Online Screening Assessment, Technical Round 1, Technical Round 2, Managerial and HR Round.
  • 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 4 reported rounds, with the weakest marked.

02Work Electrical Machines (Induction machine, motors)
  • Spend the session on Electrical Machines (Induction machine, motors), which Johnson Controls candidates report being tested on.
  • Write one worked example in Electrical Machines (Induction machine, motors) and time yourself on it.

Deliverable: One timed worked example in Electrical Machines (Induction machine, motors).

03Work Transformers (working, types)
  • Spend the session on Transformers (working, types), which Johnson Controls candidates report being tested on.
  • Write one worked example in Transformers (working, types) and time yourself on it.

Deliverable: One timed worked example in Transformers (working, types).

04Work PLC (Programmable Logic Controller) Fundamentals
  • Spend the session on PLC (Programmable Logic Controller) Fundamentals, which Johnson Controls candidates report being tested on.
  • Write one worked example in PLC (Programmable Logic Controller) Fundamentals and time yourself on it.

Deliverable: One timed worked example in PLC (Programmable Logic Controller) Fundamentals.

05Answer out loud: Core Software Engineering & Data Structures
  • Answer aloud, timed: Explain the core principles of Object-Oriented Programming (OOP) and give an example of inheritance versus composition.
  • Answer aloud, timed: What is the difference between `var`, `let`, and `const` in JavaScript, and how does scope work in dynamic languages?

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

06Answer out loud: Embedded Systems, Firmware & Hardware Integration
  • Answer aloud, timed: Explain the difference between a mutex and a semaphore in an operating system or RTOS environment.
  • Answer aloud, timed: What causes a segmentation fault in C/C++, and how do you diagnose memory leaks in low-level applications?

Deliverable: Spoken answers to 2 reported Embedded Systems, Firmware & Hardware Integration question(s), under time.

07Answer out loud: Control Systems, Industrial Protocols & Automation Logic
  • Answer aloud, timed: What is a PID controller, and how do the Proportional, Integral, and Derivative components work together to stabilize a system?
  • Answer aloud, timed: Explain the operational difference between an open-loop and a closed-loop control system.

Deliverable: Spoken answers to 2 reported Control Systems, Industrial Protocols & Automation Logic 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 faced a difficult technical challenge during a deployment. How did you resolve it?

medium
Behavioral & Team Collaboration

Describe a time when you faced a difficult technical challenge during a deployment. How did you resolve it?

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 work with a challenging team member. What steps did you take to maintain proje

medium
Behavioral & Team Collaboration

Tell me about a time you had to work with a challenging team member. What steps did you take to maintain project momentum?

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 project on your resume that best demonstrates your technical expertise and personal impact.

medium
Behavioral & Team Collaboration

Describe a project on your resume that best demonstrates your technical expertise and personal impact.

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?

Why are you interested in working at Johnson Controls, and where do you see your career path evolving in five

medium
Behavioral & Team Collaboration

Why are you interested in working at Johnson Controls, and where do you see your career path evolving in five years?

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?
  • 01

    Describe a time when you faced a difficult technical challenge during a deployment. How did you resolve it?

  • 02

    Tell me about a time you had to work with a challenging team member. What steps did you take to maintain project momentum?

  • 03

    Describe a project on your resume that best demonstrates your technical expertise and personal impact.

  • 04

    Why are you interested in working at Johnson Controls, and where do you see your career path evolving in five years?

PracHub preparation framework ↗
How difficult are the technical interviews at Johnson Controls?

The interview process is generally evaluated as moderate and fair. Technical questions focus heavily on core computer science foundations, your primary programming language, practical debugging, and real-world project experience rather than extreme algorithmic puzzles.

Johnson Controls Software Engineer candidate reports ↗
Do I need prior background in HVAC or Building Automation to be hired?

No, prior domain experience is not strictly required for general software engineering roles unless specified for a specialized field team. Showing an interest in how software interacts with physical systems and building controls is highly valued, however.

Johnson Controls Software Engineer candidate reports ↗
What is the typical timeframe from the initial interview to a job offer?

The end-to-end hiring process usually takes between two to four weeks. Timelines vary slightly depending on candidate location, team scheduling, and required background clearance procedures.

Johnson Controls Software Engineer candidate reports ↗
Are remote or hybrid working arrangements supported?

Yes, Johnson Controls offers hybrid, remote, and on-site roles depending on the scope of work. Roles that require direct interaction with physical hardware, laboratory testing equipment, or field installations require higher on-site presence.

Johnson Controls Software Engineer candidate reports ↗
How are software coding rounds conducted?

Coding evaluations are usually conducted during virtual technical rounds via screen sharing or online assessment platforms. Questions test practical problem solving—such as string/array manipulation, basic object implementation, or REST API handling—followed by discussions on optimization.

Johnson Controls Software Engineer candidate reports ↗
What topics does Johnson Controls test in interviews?

Johnson Controls interviews most often cover Stakeholder Management, Cross-functional Collaboration, Problem Solving, Stakeholder Communication, and C Programming. The exact emphasis depends on the specific role you apply for.

Johnson Controls 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.