Interview guides · Experis

Experis Software Engineer Interview Guide

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

The 60-second brief

As a Software Engineer at Experis, you occupy a pivotal role in bridging the gap between complex client requirements and high-impact technical solutions. Experis operates as a global leader in IT professional resourcing and project-based solutions, meaning you will often be embedded in diverse environments, working on projects that require both technical agility and the ability to adapt to different organizational cultures. Your work directly influences the success of our clients, ranging from enterprise-level infrastructure to specialized software development initiatives. This role is designed for engineers who thrive on variety and technical challenge. You will not only be responsible for writing clean, maintainable code but also for acting as a technical consultant who understands the business impact of your architectural decisions.

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

Focus areas

Java
SQL
Spring Framework

The Experis interview process

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

Recruiter Screen

Initial contact with a recruiter to discuss your background and assess fit for the role.

What to demonstrate

Initial contact with a recruiter to discuss your background and assess fit for the role
Depth in Java

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 Evaluation

Assessment of your technical skills relevant to the software engineering role.

What to demonstrate

Assessment of your technical skills relevant to the software engineering role
Depth in Java

How to prepare

Answer aloud and timed: What is the difference between a Class and an Interface in Java?
Answer aloud and timed: Can you explain how memory management works in Java (Garbage Collection)?

Client-Specific Discussion

Final discussion tailored to the specific client, focusing on professional fit for client-facing engagements.

What to demonstrate

Final discussion tailored to the specific client
Focusing on professional fit for client-facing engagements

How to prepare

Answer aloud and timed: How do you handle database connections efficiently in a Java-based application?
Answer aloud and timed: Describe the difference between INNER JOIN and LEFT JOIN.

Communication Assessment

Evaluation of your communication skills, particularly for roles involving international clients.

What to demonstrate

Evaluation of your communication skills, particularly for roles involving international clients
Depth in Java

How to prepare

Answer aloud and timed: How would you optimize a slow-running SQL query?
Answer aloud and timed: Explain the concept of normalization in database design.

Where candidates lose points

Be prepared to discuss your resume in detail

You will be asked about the specific technologies and projects you have listed. Know your contribution to each project.

Research the client if possible

If the recruiter mentions a specific client, research their industry and tech stack to tailor your answers.

Focus on the "Why

When explaining your technical choices, articulate the trade-offs you considered. This shows senior-level engineering maturity.

Highlight your adaptability

Mentioning instances where you quickly learned a new framework or adapted to a new team structure is highly valued at Experis.

Questions & practice

How do you implement multi-threading in Java, and what are the common pitfalls?

Medium · Technical Fundamentals (Java & Core Prog

Approach

Say what the runtime actually does before reasoning about the code.
Name what is shared across threads and what owns each piece of state.
Identify the window where an invariant is briefly untrue.
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?

Can you explain how memory management works in Java (Garbage Collection)?

Medium · Technical Fundamentals (Java & Core Prog

Approach

Say what the runtime actually does before reasoning about the code.
Name what is shared across threads and what owns each piece of state.
Identify the window where an invariant is briefly untrue.
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

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.
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.
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.
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?

Describe the difference between INNER JOIN and LEFT JOIN.

Medium · Data & Querying (SQL / PL/SQL)

Approach

Name the grain you start from and join outward from it.
Check whether any join is one-to-many before aggregating, or the sums inflate.
Say which index the query would use, and what makes it unusable.
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?

How would you optimize a slow-running SQL query?

Medium · Data & Querying (SQL / PL/SQL)

Approach

Name the grain you start from and join outward from it.
Check whether any join is one-to-many before aggregating, or the sums inflate.
Say which index the query would use, and what makes it unusable.
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 concept of normalization in database design.

Medium · Data & Querying (SQL / PL/SQL)

Approach

Name the grain you start from and join outward from it.
Check whether any join is one-to-many before aggregating, or the sums inflate.
Say which index the query would use, and what makes it unusable.
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 a stored procedure, and when should you use one versus an inline query?

Medium · Data & Querying (SQL / PL/SQL)

Approach

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

Follow-up

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

Explain the difference between the JDK, JRE, and JVM.

Medium · Technical Fundamentals (Java & Core Prog

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 is the difference between a Class and an Interface in Java?

Medium · Technical Fundamentals (Java & Core Prog

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 data integrity within your database transactions?

Medium · Data & Querying (SQL / PL/SQL)

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 structure a Spring Boot application?

Medium · Frameworks & 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?

Explain the role of Dependency Injection in modern frameworks.

Medium · Frameworks & 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?

What is the difference between monolithic and microservices architecture?

Medium · Frameworks & 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 manage data flow between components in a frontend framework like Angular or React?

Medium · Frameworks & 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?

Describe your approach to designing a scalable API.

Medium · Frameworks & 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?

Listing latency scales with page size, not with filters

Easy · n+1 · latency · query batching

The tenant listing endpoint reads resource filtered by tenant_id and status, ordered by updated_at DESC, and returns each row plus the owner's display name from app_user and the actor of that resource's latest resource_revision. p99 is 55 ms at 10 rows per page and 1.4 s at 200. Database telemetry shows 401 statements per request, each under 1 ms, and nothing in the slow-query log. Diagnose the cause and give the fix, stating the statement count per request and the p99 you expect afterwards.

Approach

Read the counters before forming a theory. 401 statements for 200 rows is one driver query plus two per row, and sub-millisecond execution with an empty slow-query log rules out a bad plan. The time is round trips, which is why it is invisible in every per-query metric and scales with rows returned rather than with filter selectivity.
Name the two per-row statements from their normalised text: a single-row app_user lookup by user_id, and a resource_revision lookup by resource_id ordered by version DESC LIMIT 1. Confirm by dropping those two response fields and watching the statement count fall to one. That locates the calls in the serialisation layer, not the repository.
Check that the arithmetic accounts for the whole gap. Measure one round trip to the replica in isolation; 400 trips at roughly 3 ms of network plus 0.2 ms of execution is about 1.3 s on top of a 55 ms baseline, which matches. If the multiplication had fallen short, the N+1 would only be part of the story and you would keep looking.
Batch both lookups. Collect owner_user_ids and resource_ids from the driver query, then issue WHERE tenant_id = $1 AND user_id = ANY($2) for the users, and PostgreSQL's SELECT DISTINCT ON (resource_id) ... WHERE resource_id = ANY($2) ORDER BY resource_id, version DESC for the latest revision, which the UNIQUE (resource_id, version) index serves directly. On an engine without DISTINCT ON, use a lateral join or a row_number window. Three statements per request at any page size.

Follow-up

The page size is capped at 200 today. What breaks first if it is raised to 2,000, and is it still this bug?
How do you stop the next N+1 from reaching production, given that no individual query is slow and the endpoint's tests pass?

Suggested practice checklist

Built from the rounds and topics Experis candidates report.

Day 1 — Map the Experis loop

Write out the reported sequence: Recruiter Screen, Technical Evaluation, Client-Specific Discussion, Communication Assessment.
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.

Day 2 — Work Java

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

Deliverable: One timed worked example in Java.

Day 3 — Work SQL

Spend the session on SQL, which Experis candidates report being tested on.
Write one worked example in SQL and time yourself on it.

Deliverable: One timed worked example in SQL.

Day 4 — Work Spring Framework

Spend the session on Spring Framework, which Experis candidates report being tested on.
Write one worked example in Spring Framework and time yourself on it.

Deliverable: One timed worked example in Spring Framework.

Day 5 — Answer out loud: Technical Fundamentals (Java & Core Programming)

Answer aloud, timed: Explain the difference between the JDK, JRE, and JVM.
Answer aloud, timed: How do you implement multi-threading in Java, and what are the common pitfalls?

Deliverable: Spoken answers to 2 reported Technical Fundamentals (Java & Core Programming) question(s), under time.

Day 6 — Answer out loud: Data & Querying (SQL / PL/SQL)

Answer aloud, timed: Describe the difference between INNER JOIN and LEFT JOIN.
Answer aloud, timed: How would you optimize a slow-running SQL query?

Deliverable: Spoken answers to 2 reported Data & Querying (SQL / PL/SQL) question(s), under time.

Day 7 — Answer out loud: Frameworks & Architecture

Answer aloud, timed: How do you structure a Spring Boot application?
Answer aloud, timed: Explain the role of Dependency Injection in modern frameworks.

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

Behavioural preparation

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

How do you handle database connections efficiently in a Java-based application?

Medium · Technical Fundamentals (Java & Core Prog

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?