Mock system design interview at Atlassian

A live 45-minute round on a question reported in Atlassian interviews, run by an AI interviewer that asks one thing at a time, probes what you say, looks at your whiteboard, and weighs what that round is reported to weigh. It ends with a debrief: a score, what was strong, what was missing.

your question

Design a URL Shortener

bit.ly at scale: turn long URLs into short codes, redirect in milliseconds from anywhere, count the clicks.

You will not see the requirements, the numbers or the design before you start. That is the point.

Walk through it first

What the Atlassian round is reported to look like

60 minutes on a whiteboard or drawing tool. Questions come from a structured set close to the products Atlassian runs, such as a tagging service shared by Jira and Confluence, and follow-ups get harder or easier as you go.

What it weighs

Clarifying questions up front, with the customer and the use cases in view
A data model and storage choice that fit the access patterns
Extensibility: adding a product or entity type without a redesign
Operational concerns: performance, reliability and cost

The common mistake

Jumping in too quickly. Pin down the use cases and the scale before drawing, because the follow-ups climb from there and a design built on the wrong requirements does not survive them.

From public interview guides and candidate reports, and Atlassian’s own interview guidance where it publishes any. Not endorsed by Atlassian. The interviewer is an AI running in that style; it is practice, not a prediction.

Start the round

Timed · 45 minutesInterview conditions. The AI interviewer owns the clock; the AI Mentor is off.With the AI Mentor · untimedNo clock, and an AI Mentor beside you to ask when you are stuck.

The interviewer’s opening question is free. Answering it is part of Pro. See an example round and its debrief →

The 11 questions this round draws from

Each is reported in Atlassian interviews. Pick one to sit, or read its reference design and walk through a strong answer first.

Design a URL Shortenerbit.ly at scale: turn long URLs into short codes, redirect in milliseconds from anywhere, count the clicks.
drawn
Design Google DocsReal-time collaborative editing: many cursors in one document, every keystroke converging to the same text, offline edits merged on reconnect.
Design a Rate LimiterA distributed service that decides, in under a millisecond, whether a request from a client is allowed under its quota.
Design DropboxKeep a folder identical on every device: upload huge files in resumable chunks, push only what changed, and reconcile two machines that both edited the same file offline.
Design a Distributed Job SchedulerRun millions of cron jobs and one-off tasks on time across a fleet, exactly once each, and keep going when a worker dies halfway through one.
Design ZapierConnect thousands of third-party apps: watch ten million triggers by polling or webhook, and run each new event through multi-step workflows on someone else’s APIs.
Design Google CalendarRecurring events, invitations, free/busy and reminders for 500 million users, correct in every time zone and synced to every device within seconds.
Design Figma500 k design files open at once, some with 200 people: objects converge live, cursors stream, and 300 MB files open in seconds.
Design GitHubHost 400 M git repositories on replicated file servers, serve 100 k fetches a second, and run pull requests, forks and webhooks on top.
Design PastebinStore and serve 10 M text pastes a day behind unguessable links: expiry that is never late, burn after reading, and abuse takedown.
Design a Webhook Delivery SystemDeliver 3 billion signed webhooks a day to a million customer endpoints, retrying for three days, without one slow endpoint delaying anyone else.

Other companies: Anthropic · Google · Meta · Amazon · OpenAI · Microsoft · Uber · DoorDash