A Software Engineer at DeepInstinct plays a pivotal role in developing and enhancing cutting-edge cybersecurity solutions that utilize deep learning technologies. This position is vital as it directly impacts the effectiveness of products that safeguard critical information for diverse clients across various industries. As part of a dynamic team, you will work on complex systems that analyze and respond to evolving threats, ensuring that our users remain protected against cyber attacks. This role is not only technically challenging but also strategically significant. You will engage with a wide array of products, contributing to the development of innovative algorithms and systems that leverage artificial intelligence for real-world applications. The collaborative environment at DeepInstinct fosters creativity and encourages engineers to explore new methodologies, making your contributions essential for both the company's growth and the security of its clientele.
Screening Call
reportedInitial call to evaluate candidate's background and fit for the role.
What to demonstrate
- Initial call to evaluate candidate's background and fit for the role
- Depth in System Design
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 Assessments
reportedMultiple assessments focusing on coding abilities and system design principles.
What to demonstrate
- Multiple assessments focusing on coding abilities and system design principles
- Depth in System Design
How to prepare
- Answer aloud and timed: Discuss your experience with deep learning frameworks and their applications in cybersecurity.
- Answer aloud and timed: How would you approach debugging a complex system?
Collaboration Evaluation
reportedAssessment of interpersonal skills and ability to contribute to team dynamics.
What to demonstrate
- Assessment of interpersonal skills and ability to contribute to team dynamics
- Depth in System Design
How to prepare
- Answer aloud and timed: Design a system that receives events from agents and sends notifications based on priority.
- Answer aloud and timed: What considerations would you make when designing a distributed system?
PracHub editorial advice for the preparation topics above.
Practice Coding
Regularly work on coding challenges to sharpen your skills and boost your confidence.
Prepare Questions
Have thoughtful questions ready for your interviewers. This shows your interest in the role and helps you assess fit.
Stay Updated
Keep abreast of the latest trends in cybersecurity and software engineering; showing awareness of current technologies can set you apart.
Be Authentic
When discussing past experiences, be honest and reflective about your contributions and learning moments.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
What are the differences between arrays and linked lists? When would you use one over the other?
What are the differences between arrays and linked lists? When would you use one over the other?
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?
Write a function to find the longest substring without repeating characters.
Write a function to find the longest substring without repeating characters.
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?
Given a list of integers, find the two numbers that add up to a specific target.
Given a list of integers, find the two numbers that add up to a specific target.
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?
Denormalise tenant onto revisions and backfill it live
resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.
Approach
- Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
- Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
- Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
- Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.
Follow-up
- The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
- How do you verify the backfill actually finished, given rows are still being inserted while it runs?
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?
Explain how you would implement LRU caching.
Explain how you would implement LRU caching.
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?
Design a system that receives events from agents and sends notifications based on priority.
Design a system that receives events from agents and sends notifications based on priority.
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?
What considerations would you make when designing a distributed system?
What considerations would you make when designing a distributed system?
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 ensure data integrity in your system designs?
How would you ensure data integrity in your system designs?
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?
Given a set of requirements, how would you structure your approach to a new project?
Given a set of requirements, how would you structure your approach to a new project?
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 would you handle a situation where a team member is not contributing equally?
How would you handle a situation where a team member is not contributing equally?
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 would you approach debugging a complex system?
How would you approach debugging a complex system?
Approach
- Establish what changed and when, before forming any theory.
- Pick a bisection that eliminates candidates whichever way it turns out.
- Check the instrumentation before believing the symptom.
- Separate the trigger from the cause; the deploy is rarely the bug.
Follow-up
- What would you look at first, and what would it rule out?
- How would you tell a cause from a coincidence here?
Built from the rounds and topics DeepInstinct candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the DeepInstinct loop
- Write out the reported sequence: Screening Call, Technical Assessments, Collaboration Evaluation.
- 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 System Design
- Spend the session on System Design, which DeepInstinct 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.
03Work LRU Caching
- Spend the session on LRU Caching, which DeepInstinct candidates report being tested on.
- Write one worked example in LRU Caching and time yourself on it.
Deliverable: One timed worked example in LRU Caching.
04Work C++ (C++11/C++14)
- Spend the session on C++ (C++11/C++14), which DeepInstinct candidates report being tested on.
- Write one worked example in C++ (C++11/C++14) and time yourself on it.
Deliverable: One timed worked example in C++ (C++11/C++14).
05Answer out loud: Technical / Domain Knowledge
- Answer aloud, timed: Explain how you would implement LRU caching.
- Answer aloud, timed: What are the differences between arrays and linked lists? When would you use one over the other?
Deliverable: Spoken answers to 2 reported Technical / Domain Knowledge question(s), under time.
06Answer out loud: System Design / Architecture
- Answer aloud, timed: Design a system that receives events from agents and sends notifications based on priority.
- Answer aloud, timed: What considerations would you make when designing a distributed system?
Deliverable: Spoken answers to 2 reported System Design / Architecture question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?
- Answer aloud, timed: How do you prioritize tasks when dealing with tight deadlines?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership 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.
Discuss your experience with deep learning frameworks and their applications in cybersecurity.
Discuss your experience with deep learning frameworks and their applications in cybersecurity.
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 challenging project you worked on. What was your role, and how did you overcome obstacles?
Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?
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 prioritize tasks when dealing with tight deadlines?
How do you prioritize tasks when dealing with tight deadlines?
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
Discuss your experience with deep learning frameworks and their applications in cybersecurity.
- 02
Describe a challenging project you worked on. What was your role, and how did you overcome obstacles?
- 03
How do you prioritize tasks when dealing with tight deadlines?
How difficult is the interview process?
The interview process can be challenging, with a mix of technical and behavioral questions. Preparation is key, and candidates often recommend dedicating a few weeks to review relevant topics and practice coding problems.
DeepInstinct Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate a strong technical foundation, effective problem-solving skills, and the ability to collaborate well with others. Clear communication and a positive attitude toward learning are also valued.
DeepInstinct Software Engineer candidate reports ↗What is the culture like at DeepInstinct?
The culture at DeepInstinct is collaborative and innovative, with a strong emphasis on teamwork and professional development. Engineers are encouraged to share ideas and contribute to the company's mission.
DeepInstinct Software Engineer candidate reports ↗How long does the interview process typically take?
The entire interview process usually spans several weeks, depending on scheduling and availability. Candidates can expect clear communication from the recruitment team throughout.
DeepInstinct Software Engineer candidate reports ↗Are remote work options available?
DeepInstinct offers flexibility in work arrangements, including remote and hybrid options, depending on the team's needs and individual preferences.
DeepInstinct Software Engineer candidate reports ↗What topics does DeepInstinct test in interviews?
DeepInstinct interviews most often cover Communication Skills, PostgreSQL, System Design, Technical Writing, and Sales Strategy. The exact emphasis depends on the specific role you apply for.
DeepInstinct 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.
- 01DeepInstinct 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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