At Superhuman, we are building the fastest email experience in the world. As a Software Engineer, you do not just write code; you craft an interface where every interaction happens in under 100 milliseconds. This relentless focus on speed, responsiveness, and delightful user experiences makes engineering at Superhuman uniquely challenging and rewarding. You will work on a highly optimized, offline-first client architecture that synchronizes millions of data points seamlessly with backend services, ensuring that users can fly through their inboxes without a single hitch. The engineering team is organized around deep craft and high ownership. Whether you specialize in frontend engineering (leveraging React, TypeScript, and native browser capabilities to build keyboard-shortcut-driven UIs) or backend systems (building ultra-fast synchronization engines, robust APIs, and local database integrations), your work directly impacts user productivity. You will solve complex problems related to local data persistence, real-time synchronization, memory management, and rendering optimization. To succeed in this role, you must possess a strong foundation in computer science, a passion for performance tuning, and a high degree of product empathy. Superhuman engineers are expected to think deeply about user workflows and build systems that are not just functionally correct, but exceptionally fast and reliable.
Technical Assessment
reportedInitial technical assessment or take-home coding challenge to establish software engineering proficiency.
What to demonstrate
- Initial technical assessment or take-home coding challenge to establish software engineering proficiency
- Depth in React
How to prepare
- Answer aloud and timed: Implement an algorithm to solve a variation of the climbing stairs problem, and provide both top-down and bottom-up dynamic programming optimizations.
- Answer aloud and timed: Given a stream of incoming data, design an efficient structure to perform search and retrieval operations in sub-linear time.
Recruiter Conversation
reportedDiscussion with a technical recruiter about your background, career aspirations, and team culture alignment.
What to demonstrate
- Discussion with a technical recruiter about your background, career aspirations, and team culture alignment
- Depth in React
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 Screening
reportedFocus on core computer science fundamentals to assess technical skills.
What to demonstrate
- Focus on core computer science fundamentals to assess technical skills
- Depth in React
How to prepare
- Answer aloud and timed: Build a small, interactive application using vanilla JavaScript or React that manages local state, handles keyboard events, and renders complex datasets efficiently.
- Answer aloud and timed: Explain the React rendering lifecycle and detail how you would prevent unnecessary re-renders in a highly dynamic, list-heavy user interface.
Virtual Onsite Loop
reportedIncludes domain-focused coding, system design, project walkthrough, and behavioral evaluation.
What to demonstrate
- Includes domain-focused coding, system design, project walkthrough, and behavioral evaluation
- Depth in React
How to prepare
- Answer aloud and timed: Implement an asynchronous task queue in your preferred backend language that supports concurrency limits, retries, and prioritization.
- Answer aloud and timed: Write a thread-safe implementation of a local cache that evicts items based on a least-recently-used (LRU) policy.
PracHub editorial advice for the preparation topics above.
Experience the Product
Take full advantage of the Superhuman trial provided to you. Pay close attention to the transitions, keyboard shortcuts, and overall responsiveness of the client. This will help you understand our engineering team's obsession with speed and user experience.
Think Offline-First
Many of our toughest engineering challenges revolve around data synchronization, local storage, and conflict resolution. When designing systems in your interviews, always consider how they would behave under poor network conditions or complete disconnection.
Saying 'eventually consistent' without naming the anomaly a user would see
Describe the concrete symptom you are choosing to accept: the author reloads and their own comment is missing for two seconds, or two devices show different balances for a minute. The class of consistency model is a technical label; the tolerable anomaly is the actual product decision.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Implement an algorithm to solve a variation of the climbing stairs problem, and provide both top-down and bott
Implement an algorithm to solve a variation of the climbing stairs problem, and provide both top-down and bottom-up dynamic programming optimizations.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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?
Solve a classic array or string manipulation problem and optimize your solution from O(N) to O(log N) or O(sqr
Solve a classic array or string manipulation problem and optimize your solution from O(N) to O(log N) or O(sqrt(N)) complexity.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- 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 asynchronous task queue in your preferred backend language that supports concurrency limits, retr
Implement an asynchronous task queue in your preferred backend language that supports concurrency limits, retries, and prioritization.
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?
Write a thread-safe implementation of a local cache that evicts items based on a least-recently-used (LRU) pol
Write a thread-safe implementation of a local cache that evicts items based on a least-recently-used (LRU) policy.
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?
Write the update path that detects a concurrent edit
resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.
Approach
- One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
- Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
- State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
- Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.
Follow-up
- A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
- Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?
Hold a per-tenant active cap against concurrent creates
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
- 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.
- 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.
- 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.
- 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?
Given a stream of incoming data, design an efficient structure to perform search and retrieval operations in s
Given a stream of incoming data, design an efficient structure to perform search and retrieval operations in sub-linear time.
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?
Implement a custom rate limiter that can handle bursty traffic across multiple client connections.
Implement a custom rate limiter that can handle bursty traffic across multiple client connections.
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?
Build a small, interactive application using vanilla JavaScript or React that manages local state, handles key
Build a small, interactive application using vanilla JavaScript or React that manages local state, handles keyboard events, and renders complex datasets efficiently.
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?
Explain the React rendering lifecycle and detail how you would prevent unnecessary re-renders in a highly dyna
Explain the React rendering lifecycle and detail how you would prevent unnecessary re-renders in a highly dynamic, list-heavy user interface.
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?
Architect a real-time notification service that scales to millions of concurrent users while keeping delivery
Architect a real-time notification service that scales to millions of concurrent users while keeping delivery latency under 50 milliseconds.
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?
Design a local database storage layer for a desktop client that balances fast read performance with memory con
Design a local database storage layer for a desktop client that balances fast read performance with memory constraints.
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 through the architecture of a complex project you designed and shipped from scratch, detailing the major
Walk through the architecture of a complex project you designed and shipped from scratch, detailing the major trade-offs and lessons learned.
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 Superhuman candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Superhuman loop
- Write out the reported sequence: Technical Assessment, Recruiter Conversation, Technical Screening, Virtual Onsite Loop.
- 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.
02Work React
- Spend the session on React, which Superhuman candidates report being tested on.
- Write one worked example in React and time yourself on it.
Deliverable: One timed worked example in React.
03Work System design
- Spend the session on System design, which Superhuman candidates report being tested on.
- Write one worked example in System design and time yourself on it.
Deliverable: One timed worked example in System design.
04Work JavaScript
- Spend the session on JavaScript, which Superhuman candidates report being tested on.
- Write one worked example in JavaScript and time yourself on it.
Deliverable: One timed worked example in JavaScript.
05Answer out loud: Computer Science & Algorithmic Problem Solving
- Answer aloud, timed: Implement an algorithm to solve a variation of the climbing stairs problem, and provide both top-down and bottom-up dynamic programming optimizations.
- Answer aloud, timed: Given a stream of incoming data, design an efficient structure to perform search and retrieval operations in sub-linear time.
Deliverable: Spoken answers to 2 reported Computer Science & Algorithmic Problem Solving question(s), under time.
06Answer out loud: Domain-Specific Engineering (Frontend & Backend)
- Answer aloud, timed: Build a small, interactive application using vanilla JavaScript or React that manages local state, handles keyboard events, and renders complex datasets efficiently.
- Answer aloud, timed: Explain the React rendering lifecycle and detail how you would prevent unnecessary re-renders in a highly dynamic, list-heavy user interface.
Deliverable: Spoken answers to 2 reported Domain-Specific Engineering (Frontend & Backend) question(s), under time.
07Answer out loud: System Design & Architecture
- Answer aloud, timed: Design an offline-first synchronization protocol that allows a web client to read, write, and queue actions while disconnected, and resolve conflicts once back online.
- Answer aloud, timed: Architect a real-time notification service that scales to millions of concurrent users while keeping delivery latency under 50 milliseconds.
Deliverable: Spoken answers to 2 reported System Design & Architecture 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.
Design an offline-first synchronization protocol that allows a web client to read, write, and queue actions wh
Design an offline-first synchronization protocol that allows a web client to read, write, and queue actions while disconnected, and resolve conflicts once back online.
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 you had to diagnose and resolve a critical performance bottleneck or memory leak in a producti
Describe a time you had to diagnose and resolve a critical performance bottleneck or memory leak in a production application.
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 disagreements with product managers or design partners regarding technical trade-offs versus
How do you handle disagreements with product managers or design partners regarding technical trade-offs versus user experience requirements?
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
Design an offline-first synchronization protocol that allows a web client to read, write, and queue actions while disconnected, and resolve conflicts once back online.
- 02
Describe a time you had to diagnose and resolve a critical performance bottleneck or memory leak in a production application.
- 03
How do you handle disagreements with product managers or design partners regarding technical trade-offs versus user experience requirements?
What is the typical timeline for the Superhuman interview process?
The entire process usually takes between 3 to 5 weeks from the initial recruiter screen to the final offer. We are highly respectful of your time and can accelerate the schedule if you have competing offers.
Superhuman Software Engineer candidate reports ↗How deeply do you test LeetCode-style algorithmic questions?
Our CS fundamentals round does feature algorithmic coding, but we focus on practical problem-solving and mathematical optimization rather than obscure trick questions. We want to see how you structure your code and optimize it for real-world constraints.
Superhuman Software Engineer candidate reports ↗Do I need to be a user of Superhuman before interviewing?
No prior experience with our product is required. However, we highly recommend utilizing the complimentary Superhuman subscription provided during the interview process to familiarize yourself with our focus on speed and keyboard-driven workflows.
Superhuman Software Engineer candidate reports ↗What is the engineering culture like at Superhuman?
Our culture is built on high ownership, continuous learning, and a deep respect for craft. We value collaborative problem-solving, open feedback, and a shared dedication to building incredibly fast, high-quality software.
Superhuman Software Engineer candidate reports ↗What topics does Superhuman test in interviews?
Superhuman interviews most often cover Problem Solving, Stakeholder Management, Systems Design, Data-Driven Decision Making, and Analytical Thinking. The exact emphasis depends on the specific role you apply for.
Superhuman Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01Superhuman Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
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