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Interview guides · Uae.

Uae. Software Engineer Interview Guide

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

The 60-second brief

A Software Engineer at Uae. plays a pivotal role in maintaining, optimizing, and evolving the core technology systems that drive our business operations. With a rich corporate history spanning over 37 years, Uae. relies on a blend of robust, time-tested legacy systems and modern, cross-functional architectures. As a engineer here, your mission is to bridge the gap between historical software reliability and modern engineering practices, ensuring our platforms remain secure, scalable, and highly performant. In this role, you will not only write clean, maintainable code but also navigate complex, multi-layered systems that have evolved over decades.

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

Focus areas

  • Legacy Systems Awareness
  • Working with Older Codebases
  • Adaptation to Unannounced Domain Constraints

The Uae. interview process

Uae. candidates report 5 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Application Review

Initial review of candidate applications by the recruiting team.

What to demonstrate

  • Initial review of candidate applications by the recruiting team
  • Depth in Legacy Systems Awareness

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.

Phone Screen

Initial contact with the recruiting team to discuss the candidate's background and role fit.

What to demonstrate

  • Initial contact with the recruiting team to discuss the candidate's background and role fit
  • Depth in Legacy Systems Awareness

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 Evaluations

Multiple technical interviews assessing coding skills and problem-solving abilities.

What to demonstrate

  • Multiple technical interviews assessing coding skills and problem-solving abilities
  • Depth in Legacy Systems Awareness

How to prepare

  • Answer aloud and timed: How do you handle exception handling and memory management in a high-throughput application?
  • Answer aloud and timed: Write a function to reverse a linked list, both iteratively and recursively.

Onsite Interview

In-depth interviews focusing on system integration and working across diverse domains.

What to demonstrate

  • In-depth interviews focusing on system integration and working across diverse domains
  • Depth in Legacy Systems Awareness

How to prepare

  • Answer aloud and timed: How would you find the first non-repeating character in a given string?
  • Answer aloud and timed: Explain the difference between a hash map and a binary search tree, including their average and worst-case time complexities.

Final Decision

Review of all evaluations and making the final hiring decision.

What to demonstrate

  • Review of all evaluations and making the final hiring decision
  • Depth in Legacy Systems Awareness

How to prepare

  • Answer aloud and timed: Implement an efficient algorithm to merge two sorted arrays.
  • Answer aloud and timed: How do you detect a cycle in a directed graph?

Where candidates lose points

Clarify Domain Assignments Early

During your interviews, proactively ask about the specific technology stack and the age of the codebase of the team you are interviewing for. Since Uae. has a mix of modern and legacy systems, getting clarity early will help set your expectations.

Emphasize Foundational Knowledge

Do not over-complicate your answers. Focus on writing clean, readable, and highly understandable code. Our interviewers value simple, elegant solutions over complex, trendy frameworks.

Demonstrate Curiosity for Legacy Tech

Show that you respect the engineering decisions of the past. Frame legacy systems not as "bad code," but as highly reliable systems that have successfully powered the business for decades.

Prepare for a Multi-Stage Journey

Because the selection process is multi-level, keep your energy high and stay consistent. Treat every interviewer with the same level of enthusiasm and professionalism.

Questions & practice

How does garbage collection work in your primary programming language?

Medium · Core Programming & OOP Fundamentals

Approach

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

Follow-up

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

Write a function to reverse a linked list, both iteratively and recursively.

Medium · Data Structures & Algorithms

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 would you find the first non-repeating character in a given string?

Medium · Data Structures & Algorithms

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 the difference between a hash map and a binary search tree, including their average and worst-case tim

Medium · Data Structures & Algorithms

Explain the difference between a hash map and a binary search tree, including their average and worst-case time complexities.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Implement an efficient algorithm to merge two sorted arrays.

Medium · Data Structures & Algorithms

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 detect a cycle in a directed graph?

Medium · Data Structures & Algorithms

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 ensure backward compatibility when introducing new APIs or database schemas to a 30-year-old system

Medium · System Adaptability & Legacy Integration

How do you ensure backward compatibility when introducing new APIs or database schemas to a 30-year-old system?

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?

Hold a per-tenant active cap against concurrent creates

Hard · write skew · isolation levels · constraints

A tenant on the standard plan may hold at most 50 resources with status='active'. The create handler runs SELECT count(*) FROM resource WHERE tenant_id = $1 AND status = 'active', compares to 50, then inserts. Two creates arrive 3 ms apart on different instances and the tenant lands at 51. Name the anomaly, say whether PostgreSQL 16 READ COMMITTED or REPEATABLE READ prevents it and why, then give an implementation that holds the cap at READ COMMITTED with the exact statements. Finally, say what changes when the cap is 'at most one running export per tenant' on job_run.

Approach

  1. Name it: write skew. The two transactions read an overlapping set and write disjoint rows, so there is no row-level conflict for the engine to detect and each commit is individually legal.
  2. Rule out the levels precisely. READ COMMITTED takes a fresh snapshot per statement and takes no lock on the counted rows, so both see 49. PostgreSQL's REPEATABLE READ is snapshot isolation: it removes non-repeatable reads and phantoms within the snapshot but still admits write skew, because the anomaly is not a re-read of a changed row, it is a read of a set that a concurrent transaction invalidates. Only SERIALIZABLE closes it, by tracking the read dependency and aborting one transaction with SQLSTATE 40001 — a guarantee that exists only if the application re-runs the whole transaction from the read.
  3. Convert the set predicate into a single-row conflict: keep tenant.active_resource_count and run UPDATE tenant SET active_resource_count = active_resource_count + 1 WHERE tenant_id = $1 AND active_resource_count < 50 in the same transaction as the INSERT. Zero affected rows is the cap, returned as 409. The row lock serialises the decision at any isolation level, and contention is bounded to one tenant's row — which is also the fair-scheduling unit, unlike a global counter that would convoy every tenant behind one row.
  4. State the cost you just took on: a counter is a second source of truth that can drift, so every path that changes status must adjust it inside the same transaction, and a periodic reconciliation has to exist, with resource_revision as the authority for what the count should have been.

Follow-up

  • A resource moves from archived back to active. Which statements change, and what breaks if the counter update and the status change land in different transactions?
  • The cap becomes plan-dependent and a plan can change mid-month. Where does the number 50 live, and who reads it?

Explain the difference between inheritance and composition, and when you would use each.

Medium · Core Programming & OOP Fundamentals

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 are the SOLID design principles, and how do they contribute to writing maintainable code?

Medium · Core Programming & OOP Fundamentals

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?

Describe the difference between abstract classes and interfaces.

Medium · Core Programming & OOP Fundamentals

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 do you approach learning and working with a codebase written in an older language or framework that you ha

Medium · System Adaptability & Legacy Integration

How do you approach learning and working with a codebase written in an older language or framework that you have not used before?

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

What strategies do you use to document and understand a large, undocumented codebase?

Medium · System Adaptability & Legacy Integration

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

p99 jumped on one listing filter while p50 stayed flat

Medium · query planning · composite index · percentiles

After a release that added an owner_user_id filter to the resource listing, p99 rose from 90 ms to 1.9 s while p50 stayed at 40 ms. Traffic and row counts are unchanged. resource carries the index (tenant_id, status, updated_at DESC, resource_id DESC). The new query filters tenant_id and owner_user_id, orders by updated_at DESC, resource_id DESC, and takes 20 rows. On PostgreSQL, explain the shape of the regression, prove it from a query plan, and give the index you would add.

Approach

  1. Start from the shape. A flat p50 with a moved p99 means a subset of requests changed cost, not all of them, so the first job is naming the subset. Bucket the endpoint's latency by the tenant's row count; the natural hypothesis is that large tenants are a small share of requests and all of the tail.
  2. Get the plan for the new query on a large tenant with EXPLAIN (ANALYZE, BUFFERS). Expect an index scan over the tenant's range, a filter discarding most of it, then a Sort feeding the Limit, possibly reporting Sort Method: external merge Disk. Read actual rows on the scan node, not estimated.
  3. Explain why the existing index cannot serve it. A composite B-tree is seekable only as a left prefix, and with no equality predicate on status the scan cannot treat updated_at as an ordering, because rows in the tenant's range are ordered by status first. Everything matching must be read and sorted before LIMIT 20 can apply, so a tenant with 400,000 rows pays 400,000 rows to return 20.
  4. Add (tenant_id, owner_user_id, updated_at DESC, resource_id DESC). Equality on the first two columns leaves the index ordered by updated_at within that pair, so the plan becomes an index scan that stops after 20 rows with no Sort node. PostgreSQL can scan a B-tree backwards, so the DESC markers matter only if the two sort columns ever disagree in direction; keeping them explicit documents the order the keyset cursor depends on.

Follow-up

  • The endpoint paginates with OFFSET. What does page 500 cost with your index, and what does the keyset version cost?
  • How would you have caught this before release, given that a 10,000-row seed database produces the same plan shape at an unnoticeable cost?

Suggested practice checklist

Built from the rounds and topics Uae. candidates report.

Day 1 — Map the Uae. loop

  • Write out the reported sequence: Application Review, Phone Screen, Technical Evaluations, Onsite Interview, Final Decision.
  • 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 5 reported rounds, with the weakest marked.

Day 2 — Work Legacy Systems Awareness

  • Spend the session on Legacy Systems Awareness, which Uae. candidates report being tested on.
  • Write one worked example in Legacy Systems Awareness and time yourself on it.

Deliverable: One timed worked example in Legacy Systems Awareness.

Day 3 — Work Working with Older Codebases

  • Spend the session on Working with Older Codebases, which Uae. candidates report being tested on.
  • Write one worked example in Working with Older Codebases and time yourself on it.

Deliverable: One timed worked example in Working with Older Codebases.

Day 4 — Work Adaptation to Unannounced Domain Constraints

  • Spend the session on Adaptation to Unannounced Domain Constraints, which Uae. candidates report being tested on.
  • Write one worked example in Adaptation to Unannounced Domain Constraints and time yourself on it.

Deliverable: One timed worked example in Adaptation to Unannounced Domain Constraints.

Day 5 — Answer out loud: Core Programming & OOP Fundamentals

  • Answer aloud, timed: Explain the difference between inheritance and composition, and when you would use each.
  • Answer aloud, timed: How does garbage collection work in your primary programming language?

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

Day 6 — Answer out loud: Data Structures & Algorithms

  • Answer aloud, timed: Write a function to reverse a linked list, both iteratively and recursively.
  • Answer aloud, timed: How would you find the first non-repeating character in a given string?

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

Day 7 — Answer out loud: System Adaptability & Legacy Integration

  • Answer aloud, timed: How do you approach learning and working with a codebase written in an older language or framework that you have not used before?
  • Answer aloud, timed: Describe a time when you had to refactor a legacy system. What risks did you identify, and how did you mitigate them?

Deliverable: Spoken answers to 2 reported System Adaptability & Legacy Integration question(s), under time.

Behavioural preparation

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

How do you handle exception handling and memory management in a high-throughput application?

Medium · Core Programming & OOP Fundamentals

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 time when you had to refactor a legacy system. What risks did you identify, and how did you mitigat

Medium · System Adaptability & Legacy Integration

Describe a time when you had to refactor a legacy system. What risks did you identify, and how did you mitigate them?

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 callers you do not own that their integration breaks

Medium · deprecation · compatibility · stakeholders

A field in a write endpoint's response must change shape. You own the endpoint; you do not own the four internal callers or the outbound webhook consumers who read it. Describe a deprecation you were responsible for: what you shipped first, how you established who was actually reading the field, the window you gave and what set its length, what you did about the consumer who never moved, and how you decided removal was safe. Name the signal you used, not the announcement you sent.

Approach

  1. Establish the reader set empirically rather than from a wiki of owners: per-field usage counters keyed by principal, or access logs attributed to a consumer. State the blind spot of whichever you pick, since a consumer that reads the field only on a monthly job will not appear in a week of logs.
  2. Ship additive first. Populate the new field alongside the old one so no reader is forced to move, which is also what keeps a rolling deploy safe, because old and new instances answer the same requests at the same time and a rollback must still find the old shape present.
  3. Set the window from the slowest legitimate consumer's release cadence, not from your calendar, and decide separately what to do for a consumer with no release process at all, such as an external webhook endpoint you can only email.
  4. Convert silence into evidence before you rely on it: a short, low-traffic removal window that makes a still-dependent consumer fail visibly and loudly while you are watching, rather than at three in the morning after you have moved on.

Follow-up

  • How would you detect a consumer that reads the field only during a monthly export?
  • One caller refuses to move and has a commercial relationship behind it. What changes in your plan and what does not?