Atlassian Interview Questions — Page 8

Atlassian·Software Engineer·Onsite - System Design / Architecture

Jun 2026

Atlassian system design round that went deep on graph modeling and dynamic LCA/LCO queries. The problem felt approachable at first glance but the DAG wrinkle and mutation requirements made it genuinely hard to reason through cleanly.

Design a data model for an organization structure where orgs form a DAG (not a tree), employees can belong to multiple orgs at once, and both org memberships and parent relationships can change at runtime.
Given the mutable DAG structure, how would you implement an LCO query (lowest common organization for two employees) and what are the trade-offs between recomputing on each query versus maintaining incremental ancestor structures?
How do you handle consistency between reads and writes for LCO queries when org memberships and parent relationships are being mutated concurrently?
Given expected read/write ratios, which data structure or approach wins for the LCO problem, and how does that change if the system is read-heavy versus write-heavy?

“I started with the obvious adjacency list and it felt fine until they pushed on multi-parent orgs.”

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Atlassian·Machine Learning Engineer·Onsite - System Design / Architecture

Jun 2026

Atlassian ML Engineer interview with a system design coding round centered on interval management. The problem was more involved than I expected for an MLE role, felt more like a backend SWE question with a thin ML wrapper.

Design and implement a tennis court reservation system that supports booking a time interval on a court, cancelling an exact booking, and querying whether a court is occupied at a given time. Walk through the data structure you'd use to maintain non-overlapping intervals per court and the time complexity of each operation.
Extend the reservation system to support rescheduling a booking and finding the next available slot of a given length on a specific court.

“I went with a sorted map per court keyed by start time, which let me do a predecessor lookup to check for overlap in O(log n).”

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Atlassian·Software Engineer·Technical Phone Screen

Jun 2026

Atlassian coding round, tree problem that looked straightforward until I started second-guessing my traversal approach mid-interview. Not my cleanest performance but I got through it.

Given an organization modeled as a tree (each employee belongs to exactly one org, each org has at most one parent), find the lowest common ancestor of two given employees. Walk through your data structure choice, traversal strategy, and complexity.

“I went with the set-of-ancestors approach first: walk up from one node collecting all ancestors, then walk up from the other and return the first match.”

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Atlassian·Software Engineer·Technical Phone Screen

Jun 2026

Atlassian software engineering interview with two meaty coding problems back to back. Both leaned heavy on data structures and design, less about grinding leetcode patterns and more about thinking through tradeoffs out loud.

Design and implement a grid-based snake game with a clean API. The snake starts at the top-left corner moving right. Food items are consumed in order, and eating one grows the snake. Each step call returns the current score or -1 on collision. The solution should run in O(1) time per step.
Given an n-ary tree representing an org chart (only child pointers, no parent pointers), find the lowest common manager of two employees. Handle cases where either employee might not exist in the tree. Discuss both a single-query approach and a preprocessing approach for many queries.

“This one took me a minute to even figure out what data structure to use.”

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Atlassian·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at Atlassian where the prompt was a direct continuation of a prior coding round, so they expected me to already have context on the rate limiter I'd built. Felt like a deep dive more than a fresh problem, which was both helpful and a little disorienting.

Should a rate limiter be deployed as a library embedded in the API Gateway, or as a separate standalone service? What are the tradeoffs?
When multiple API Gateways or services share rate limiting state, how do you handle consistency? What are the failure modes?
What backing store would you choose for the rate limiter, SQL vs DynamoDB vs Redis, and how do you handle concurrent updates safely?
How would you scale this rate limiter to handle Atlassian-scale traffic? Think about sharding, autoscaling, and caching layers.

“I started with the library approach because it felt simpler and lower latency, no network hop.”

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Atlassian·Software Engineer·Technical Phone Screen

Jun 2026

Atlassian software engineering interview that went pretty deep into tree problems and system design. The question had a lot of layers to it and I wasn't fully prepared for how far they'd push on the operational side of things.

Given an organizational hierarchy represented as a tree, find the lowest common ancestor for two or more employees. You're also expected to write unit tests, explain your tree representation, and discuss how you'd handle dynamic user/group additions and deletions in a thread-safe way.

“The LCA part I was fine with.”

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Atlassian·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at Atlassian for a software engineer role. The question was a deep dive into building a real-time event filtering pipeline, and it covered basically every layer of the stack from ingestion to fault tolerance.

Design a streaming data pipeline that ingests high-throughput events and continuously filters out bad data based on configurable rules. Cover ingestion, real-time processing, rule evaluation, scaling, fault tolerance, ordering guarantees, exactly-once delivery, and how rules are versioned and updated.

“This was a lot to hold in your head at once.”

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Atlassian·Machine Learning Engineer·Technical Phone Screen

Jun 2026

Atlassian ML engineer interview with a sliding window coding problem. Pretty standard stuff but the implementation details tripped me up more than I expected.

Design a MovingAverage class that takes a window size on initialization and supports a next() method which appends a new integer to the stream and returns the average of the most recent N values.

“Felt fine about the core idea (circular buffer or a deque), but I fumbled the edge case where the stream hasn't filled up to the window size yet.”

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Atlassian·Machine Learning Engineer·Technical Phone Screen

Jun 2026

Coding round for an ML Engineer role at Atlassian. One algorithmic problem, interval scheduling flavor, the kind of thing that sounds straightforward until you're actually trying to explain your greedy logic out loud.

Given a list of bookings each with a start and end time, assign them to courts such that no two bookings on the same court overlap. Return the minimum number of courts required and a valid assignment of bookings to courts.

“Classic interval scheduling problem but the assignment part tripped me up a bit.”

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Atlassian·Software Engineer·Onsite - Coding / Algorithms

Jun 2026

Atlassian software engineer interview with a system design coding problem that looked straightforward on the surface but had some real implementation teeth once you got into the details.

Design a data structure that supports four operations all in O(1) average time: increment a key's count, decrement a key's count (and remove it if it hits zero), get any key with the maximum count, and get any key with the minimum count.

“I knew a hashmap alone wouldn't cut it for the max/min ops.”

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