At Publicis Groupe, technology is the driving engine behind global digital business transformation. As a Software Engineer, you will not simply write code for static websites; you will build high-performance, enterprise-grade digital platforms, personalization engines, and marketing technology solutions for some of the world's most recognizable brands. Your work directly impacts how millions of users interact with digital products daily, bridging the gap between cutting-edge technology and impactful brand experiences. You will collaborate closely with cross-functional teams across Publicis Groupe’s specialized networks, such as Publicis Sapient and Epsilon, as well as regional tech hubs like Ingenious Lion. This unique position gives you exposure to massive datasets, cloud-native architectures, and modern frontend frameworks. The engineering culture here values agility, scalability, and clean code, making it an ideal environment for engineers who want to see their work deliver immediate, real-world business value. ##### Tip While Publicis Groupe is a global advertising giant, its engineering division operates like a modern product company, focusing heavily on cloud scale and user-centric frontend experiences.
HR Screening
reportedInitial screening to align your background and experience with the job description.
What to demonstrate
- Initial screening to align your background and experience with the job description
- Depth in Python
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
reportedProctored language proficiency test or online coding assessment to establish coding speed and accuracy.
What to demonstrate
- Proctored language proficiency test or online coding assessment to establish coding speed and accuracy
- Depth in Python
How to prepare
- Answer aloud and timed: What is the difference between Redux and the Context API for state management in a large-scale application?
- Answer aloud and timed: How do you optimize a React application to prevent unnecessary re-renders?
Live Interviews
reportedInterviews with senior engineers and hiring managers to further assess technical capabilities.
What to demonstrate
- Interviews with senior engineers and hiring managers to further assess technical capabilities
- Depth in Python
How to prepare
- Answer aloud and timed: What factors do you consider when deciding to install a third-party NPM package versus writing a custom solution?
- Answer aloud and timed: Write a simple program in Python that demonstrates basic data manipulation and explain how you would optimize its execution time.
PracHub editorial advice for the preparation topics above.
Going into the loop without having done this.
Structure Your Code Reviews Carefully: When asked to review code during an interview, do not just look for syntax errors. Walk your interviewer through potential runtime errors, security vulnerabilities (like SQL injection), performance bottlenecks, and readability improvements.
Going into the loop without having done this.
Be Ready for Layout Questions: If you are interviewing for a frontend or full-stack role, do not overlook CSS. Interviewers frequently ask candidates to explain layout properties like CSS Grid and Flexbox in detail to ensure you can build clean, modern interfaces.
Going into the loop without having done this.
Clarify Take-Home Assignments Early: If your process includes a take-home assignment, make sure you understand the scope, evaluation criteria, and expected time commitment. Treat the submission as production-ready code, complete with clean formatting and basic tests.
Going into the loop without having done this.
If you are given a take-home assignment, treat it as production-ready code. Interviewers will review it for design patterns, error handling, and test coverage.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Given a block of code that uses a `foreach` loop to insert records into a database, identify any potential per
Given a block of code that uses a foreach loop to insert records into a database, identify any potential performance risks and explain how you would refactor it.
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?
Archive a resource graph without breaking live references or recursing
Resources reference other resources within a tenant; for the largest tenant the reference table holds up to 2,000,000 nodes and 8,000,000 edges. Archiving a resource must archive everything reachable from it that nothing outside the set still references, refuse when a live external referrer exists, and terminate when references form cycles, which they legitimately do. Produce the archive order and the refusal list, targeting O(V+E). Say what stops the traversal crossing a tenant boundary, and why recursion is the wrong control structure at this size.
Approach
- Load the subgraph with the tenant predicate on both endpoints of the edge, not only on the side you started from. Scoping the left table alone is the classic cross-tenant leak: one mis-entered edge then pulls another tenant's resources into the traversal and, worse, into the archive.
- Traverse iteratively with an explicit stack. A 2,000,000-node graph can hold a chain deep enough to exhaust a native stack in the low tens of thousands of frames, and that failure is a process crash rather than an error you can return.
- Treat cycles as data rather than corruption: compute strongly connected components with Tarjan in O(V+E) using its own explicit stack, then condense. The condensation is a DAG, so a topological order over it gives the archive order, and every member of a component archives in one transaction because no order within a cycle is valid.
- Decide refusals with reverse edges. A candidate is archivable only if every in-edge originates inside the candidate set, so build the transpose or count in-degrees restricted to the visited set, and emit each blocked resource with the id of the external referrer, which is the only part of the answer an operator can act on.
Follow-up
- The graph is read in one query and the archive writes a minute later. What can change in between, and how do you make the write safe?
- The candidate set is 400,000 resources. Is that one transaction, and if not, what does a half-finished archive look like to a reader?
Identify the heaviest tenants in a five-minute window under memory pressure
The edge service handles about 3,000 requests per second across roughly 50,000 tenants, peaking near 9,000. Expose the 50 heaviest tenants by request count over the trailing five minutes so limits can be tightened before one tenant's backfill starves the fleet. You may not retain five minutes of raw records. Give the exact solution and its memory, then the bounded-memory approximation with its error stated as a formula, and say which you would ship and at what tenant cardinality that choice changes.
Approach
- Do the exact version first, because it is affordable at this cardinality: a ring of 300 one-second counters per tenant, advanced lazily, is 1,200 bytes of counters per tenant and roughly 60 to 90 MB for 50,000 tenants with overhead. Carry a running total and subtract the bucket you overwrite so a window read is O(1) rather than 300 adds.
- Extract the top 50 with a size-k min-heap over the tenant sums: O(d log k) for d tenants, against O(d log d) to sort them all. Maintaining the heap continuously instead of on query requires a tenant-to-heap-index map, because incrementing a count already inside the heap means sifting from a known position, and without that map you rebuild the heap on every request.
- State the approximation precisely rather than gesturing at sketches. Misra-Gries with m counters retains every item whose true count exceeds N/(m+1), and each retained count underestimates the truth by at most N/(m+1). With m = 1,000 and N = 900,000 requests in the window the error is roughly 900 requests, which is fine for spotting a tenant sending 50,000 and useless for ranking two tenants 200 apart.
- Say what breaks when the window slides: Misra-Gries and Space-Saving are insert-only and cannot be decremented as records age out. The workable construction is one summary per sub-window, say ten seconds, with 30 summaries merged at query time, and the merged error is the sum of the per-summary errors, so the bound degrades linearly in the number of sub-windows.
Follow-up
- The heaviest tenant is heavy because of one export job rather than user traffic. Should the limiter treat those as the same tenant?
- Two tenants sit tied at the boundary of the top 50. Does your answer flap, and does the flapping matter?
What are the security risks associated with dynamically building database queries, and how do you prevent SQL
What are the security risks associated with dynamically building database queries, and how do you prevent SQL injection?
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 why the owner filter ignores the listing index
The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.
Approach
- Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
- For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
- Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
- Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.
Follow-up
- 90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
- A dashboard runs this for 40 owners in one page load. What changes about the design?
Explain the difference between CSS Grid and Flexbox, and describe when you would choose one over the other.
Explain the difference between CSS Grid and Flexbox, and describe when you would choose one over the other.
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 React Hooks work, and what are the rules of hooks you must follow?
How do React Hooks work, and what are the rules of hooks you must follow?
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 Redux and the Context API for state management in a large-scale application?
What is the difference between Redux and the Context API for state management in a large-scale application?
Approach
- Say who the caller is and what they do when the call fails halfway.
- Define the identity of a request so a retry cannot double-apply it.
- Separate accepted, pending, failed and confirmed; they are different facts.
- 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 do you optimize a React application to prevent unnecessary re-renders?
How do you optimize a React application to prevent unnecessary re-renders?
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 factors do you consider when deciding to install a third-party NPM package versus writing a custom soluti
What factors do you consider when deciding to install a third-party NPM package versus writing a custom solution?
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?
Write a simple program in Python that demonstrates basic data manipulation and explain how you would optimize
Write a simple program in Python that demonstrates basic data manipulation and explain how you would optimize its execution time.
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 apply AWS well-architected design principles to ensure high availability and fault tolerance?
How do you apply AWS well-architected design principles to ensure high availability and fault tolerance?
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 would you structure a decoupled, microservices-based application to handle sudden spikes in user traffic?
How would you structure a decoupled, microservices-based application to handle sudden spikes in user traffic?
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 package management and dependency resolution in a large, multi-team codebase.
Describe your approach to package management and dependency resolution in a large, multi-team codebase.
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?
Walk me through a challenging technical project you recently completed, focusing on your specific contribution
Walk me through a challenging technical project you recently completed, focusing on your specific contributions and the architectural decisions you made.
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?
Every query on one table stalls for forty seconds mid-deploy
During a release on PostgreSQL, every query touching resource times out for about 40 seconds and then recovers with no intervention. The release ran one migration, ALTER TABLE resource ADD COLUMN archived_reason TEXT, and the migration log shows it completing in 6 ms. Unrelated tables showed no change in error rate. Explain how a 6 ms statement caused a 40-second stall, give the ordered checks you would run on a live system to confirm it, and give the migration procedure that prevents a repeat.
Approach
- Separate the statement's duration from the lock's duration. ADD COLUMN with no default is a catalogue-only change and genuinely runs in milliseconds, but it requires ACCESS EXCLUSIVE, and it cannot acquire that until every transaction already touching the table has finished.
- Account for the queueing, which is the part that surprises people. A lock request that is waiting blocks later requests for conflicting modes behind it rather than letting them overtake, so one long-open transaction holds the DDL and the DDL holds all the traffic. The stall length is set by the longest open transaction, not by the size of the change.
- Confirm on a live system in this order: pg_stat_activity for that table ordered by xact_start, looking for the oldest transaction and specifically for state = idle in transaction; then pg_locks where granted = false to find the waiter; then join them on pid to name blocker and blocked. pg_blocking_pids() does that join for you and is the fastest single call.
- Prevent rather than merely time it better. Set lock_timeout to a second or two on the migration session so the DDL abandons the queue after a bounded wait and is retried, instead of holding it for as long as the oldest transaction lives. Be exact about what that buys: queries arriving during the wait still queue behind the pending ACCESS EXCLUSIVE request, so each attempt costs them up to one lock_timeout of added latency. The outage goes from 40 seconds to about one second per attempt, not to zero. Also run migrations away from deploy-time peaks, and put a statement timeout and an idle-in-transaction timeout on the analytics role that opens the long transactions.
Follow-up
- The same release also wants NOT NULL on that column. What is the sequence that gets there without a long lock?
- Your lock_timeout retry fails ten times in a row because the analytics transaction is always open. What do you change?
Built from the rounds and topics Publicis Groupe candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Publicis Groupe loop
- Write out the reported sequence: HR Screening, Technical Evaluation, Live 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 Python
- Spend the session on Python, which Publicis Groupe candidates report being tested on.
- Write one worked example in Python and time yourself on it.
Deliverable: One timed worked example in Python.
03Work React
- Spend the session on React, which Publicis Groupe candidates report being tested on.
- Write one worked example in React and time yourself on it.
Deliverable: One timed worked example in React.
04Work AWS Design Principles
- Spend the session on AWS Design Principles, which Publicis Groupe candidates report being tested on.
- Write one worked example in AWS Design Principles and time yourself on it.
Deliverable: One timed worked example in AWS Design Principles.
05Answer out loud: Frontend & UI Development
- Answer aloud, timed: Explain the difference between CSS Grid and Flexbox, and describe when you would choose one over the other.
- Answer aloud, timed: How do React Hooks work, and what are the rules of hooks you must follow?
Deliverable: Spoken answers to 2 reported Frontend & UI Development question(s), under time.
06Answer out loud: Backend & Database Engineering
- Answer aloud, timed: Write a simple program in Python that demonstrates basic data manipulation and explain how you would optimize its execution time.
- Answer aloud, timed: Given a block of code that uses a `foreach` loop to insert records into a database, identify any potential performance risks and explain how you would refactor it.
Deliverable: Spoken answers to 2 reported Backend & Database Engineering question(s), under time.
07Answer out loud: System Architecture & Design
- Answer aloud, timed: How do you apply AWS well-architected design principles to ensure high availability and fault tolerance?
- Answer aloud, timed: How would you structure a decoupled, microservices-based application to handle sudden spikes in user traffic?
Deliverable: Spoken answers to 2 reported System Architecture & Design 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.
How do you handle database transaction failures to ensure data consistency and prevent partial writes?
How do you handle database transaction failures to ensure data consistency and prevent partial writes?
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 situations where a team member is not aligned with the technical direction of a project?
How do you handle situations where a team member is not aligned with the technical direction of a project?
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 had to quickly learn a new technology or framework to deliver a critical feature.
Describe a time when you had to quickly learn a new technology or framework to deliver a critical feature.
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
How do you handle database transaction failures to ensure data consistency and prevent partial writes?
- 02
How do you handle situations where a team member is not aligned with the technical direction of a project?
- 03
Describe a time when you had to quickly learn a new technology or framework to deliver a critical feature.
How difficult is the technical interview process at Publicis Groupe?
The technical difficulty is generally rated as average. The focus is heavily placed on practical coding, language fundamentals, and real-world scenarios (such as code reviews and basic database operations) rather than highly abstract, competitive-programming puzzles.
Publicis Groupe Software Engineer candidate reports ↗What is the typical timeline from the first HR screen to an offer?
The process is relatively fast, often taking between two to three weeks. However, candidates occasionally experience communication delays during regional coordination or background checks, so staying in proactive contact with your recruiter is recommended.
Publicis Groupe Software Engineer candidate reports ↗Are there regional differences in how the interview is conducted?
Yes. While the core evaluation criteria remain consistent, some locations (such as India and Colombia) rely more heavily on initial proctored language and coding tests, while offices in the US and UK may place a higher emphasis on live technical conversations with hiring managers.
Publicis Groupe Software Engineer candidate reports ↗Does Publicis Groupe allow remote or hybrid working arrangements?
Yes, Publicis Groupe offers flexible working models, including hybrid and remote options, depending on the specific team, client requirements, and local office policies. This will typically be discussed during your initial HR screening.
Publicis Groupe Software Engineer candidate reports ↗How hard is the Publicis Groupe interview?
Candidates most commonly rate Publicis Groupe interviews as medium, based on 514 reported interviews. About 56% of candidates who interview go on to receive an offer.
Publicis Groupe Software Engineer candidate reports ↗What topics does Publicis Groupe test in interviews?
Publicis Groupe interviews most often cover SQL, Python, React, JavaScript, and React Hooks. The exact emphasis depends on the specific role you apply for.
Publicis Groupe Software Engineer candidate reports ↗Is Publicis Groupe a good place to work?
Employees rate Publicis Groupe 3.8 out of 5 overall, based on aggregated workplace reviews spanning career growth, work-life balance, compensation, culture, and management.
Publicis Groupe Software Engineer candidate reports ↗Where is Publicis Groupe headquartered?
Publicis Groupe is headquartered in Paris, France.
Publicis Groupe Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
Official role evidence, timestamped platform data and clearly labeled preparation advice.
- 01Publicis Groupe Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
candidate · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
platform · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
platform · Accessed 2026-09-22
Explore related engineering environments and compare the preparation focus.
Veem Software Engineer Interview Guide
What Veem asks Software Engineer candidates, from reported rounds and questions.
The Sparks Foundation Software Engineer Interview Guide
What The Sparks Foundation asks Software Engineer candidates, from reported rounds and questions.
Sorint.SEC Software Engineer Interview Guide
What Sorint.SEC asks Software Engineer candidates, from reported rounds and questions.
Playstation Network Software Engineer Interview Guide
What Playstation Network asks Software Engineer candidates, from reported rounds and questions.