As a Software Engineer at SwissBorg, you are at the forefront of bridging the gap between traditional finance and decentralized finance (DeFi). You will be responsible for building, scaling, and maintaining high-performance, resilient distributed systems that power the SwissBorg App and its core features, such as the Smart Engine. The Smart Engine is a highly complex routing system that connects to multiple cryptocurrency exchanges in real-time to find the best liquidity and execution prices for over a million users. Your work directly impacts the financial security, transaction speed, and overall user experience of a rapidly growing Web3 ecosystem. The engineering culture at SwissBorg emphasizes functional programming, high-throughput microservices, and absolute reliability. Because you will be handling real-time financial transactions and blockchain integrations, your code must be highly optimized, secure, and capable of handling massive concurrency under volatile market conditions. This position is ideal for engineers who thrive on solving complex distributed systems problems, appreciate the elegance of functional programming, and are deeply curious about the future of the crypto and Web3 ecosystem. It is a high-visibility role where your architectural decisions will directly shape the scalability of 's proprietary financial products. SwissBorg
Application Review
reportedInitial review of your application to assess qualifications and fit for the role.
What to demonstrate
- Initial review of your application to assess qualifications and fit for the role
- Depth in Technical Challenge / Take-home Assignment
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 Take-home Assignment
reportedComplete a technical assignment to demonstrate your coding skills and problem-solving abilities.
What to demonstrate
- Complete a technical assignment to demonstrate your coding skills and problem-solving abilities
- Depth in Technical Challenge / Take-home Assignment
How to prepare
- Answer aloud and timed: Write a Scala function that safely handles asynchronous computations and potential failures without throwing exceptions.
- Answer aloud and timed: What are type classes in Scala, and how do they differ from traditional inheritance?
Behavioral Interview
reportedEngage in a conversational interview focusing on your communication style and behavioral traits.
What to demonstrate
- Engage in a conversational interview focusing on your communication style and behavioral traits
- Depth in Technical Challenge / Take-home Assignment
How to prepare
- Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
- Re-read the description of the behavioral interview above and write down what you would ask to confirm before it.
Executive-level Conversations
reportedParticipate in discussions with executives to evaluate alignment with the company's vision.
What to demonstrate
- Participate in discussions with executives to evaluate alignment with the company's vision
- Depth in Technical Challenge / Take-home Assignment
How to prepare
- Answer aloud and timed: Explain how you would implement a rate-limiting mechanism for our public APIs.
- Answer aloud and timed: How do you handle database replication lag and eventual consistency in a microservices architecture?
Feedback and Decision
reportedReceive constructive feedback and await the final decision regarding your application.
What to demonstrate
- Receive constructive feedback and await the final decision regarding your application
- Depth in Technical Challenge / Take-home Assignment
How to prepare
- Answer aloud and timed: What strategies would you use to prevent race conditions when multiple users attempt to execute trades simultaneously?
- Answer aloud and timed: How do you design systems to be resilient against external exchange API outages?
PracHub editorial advice for the preparation topics above.
Master functional programming fundamentals
If you are transitioning from an imperative background, make sure you can explain functional concepts like immutability, pure functions, and referential transparency clearly.
Prepare for the roleplay interview
Do not just focus on coding. Practice how you would handle real-world engineering challenges, such as negotiating technical debt with product managers or handling a production incident.
Understand the SwissBorg product suite
Download the SwissBorg App, understand how the Smart Engine works, and familiarize yourself with the BORG token utility before your interviews.
Be ready for strategic crypto questions
In your conversation with the CEO, expect to discuss market trends, DeFi, and your personal motivations for working in the crypto space. Be prepared to voice your own opinions on where the industry is heading.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
How does the Akka/Pekko actor model handle state, concurrency, and fault tolerance?
How does the Akka/Pekko actor model handle state, concurrency, and fault tolerance?
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 Scala function that safely handles asynchronous computations and potential failures without throwing e
Write a Scala function that safely handles asynchronous computations and potential failures without throwing exceptions.
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?
How do you optimize garbage collection and memory usage in a high-throughput JVM application?
How do you optimize garbage collection and memory usage in a high-throughput JVM application?
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?
What strategies would you use to prevent race conditions when multiple users attempt to execute trades simulta
What strategies would you use to prevent race conditions when multiple users attempt to execute trades simultaneously?
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?
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?
Find version gaps and relay lag with window functions
outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.
Approach
- Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
- Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
- Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
- Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.
Follow-up
- Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
- Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?
Explain the difference between `Future` and task-based effects (like Cats Effect or ZIO) in Scala.
Explain the difference between Future and task-based effects (like Cats Effect or ZIO) in Scala.
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?
What are type classes in Scala, and how do they differ from traditional inheritance?
What are type classes in Scala, and how do they differ from traditional inheritance?
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 design a distributed transaction system that guarantees "exactly-once" processing?
How would you design a distributed transaction system that guarantees "exactly-once" processing?
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?
Explain how you would implement a rate-limiting mechanism for our public APIs.
Explain how you would implement a rate-limiting mechanism for our public APIs.
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 do you handle database replication lag and eventual consistency in a microservices architecture?
How do you handle database replication lag and eventual consistency in a microservices architecture?
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 do you design systems to be resilient against external exchange API outages?
How do you design systems to be resilient against external exchange API outages?
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?
Read latency spikes on a sixty-second sawtooth
The cached listing read path serves about 14k reads/second at an 85% hit rate. p99 sits at 35 ms for 57 seconds, jumps to 900 ms for 3, and repeats. During each spike the primary shows several hundred identical listing queries starting within the same millisecond, all carrying one large tenant's id. Cache entries use a 60-second TTL. Give the mechanism, the ordered checks, the fix, and the correctness hazard your fix must not introduce.
Approach
- Match the period to a configured number before theorising about load. A spike every 60 seconds against a 60-second TTL is an entry expiring, and you confirm it by correlating spike timestamps with the entry's write time rather than with the traffic curve. If the period had matched a cron or a GC interval instead, this is a different investigation.
- Establish the concurrency of the miss. Several hundred identical queries in one millisecond means the miss path has no coalescing: every request that arrives between expiry and repopulation recomputes. The herd size is that key's arrival rate times its recompute time, so at 1.2k reads/second for the hot key and a 250 ms recompute you expect about 300 concurrent misses, which matches what is observed.
- Add single-flight on the miss path so one caller per key recomputes under a short-lived lock while the rest wait for its result. Prefer stale-while-revalidate where the read tolerates it: return the expired value immediately and refresh asynchronously, which removes the latency spike rather than serialising it into a queue of waiters.
- De-synchronise the keys. Write TTLs with jitter, for example 60 seconds plus or minus 10%, so a deploy or a mass invalidation does not align every key on the same second and turn a per-key herd into a fleet-wide one.
Follow-up
- The same sawtooth appears on a key that is invalidated on write rather than expired. Is that the same bug?
- How does your answer change if the recompute takes 4 seconds instead of 250 ms?
Built from the rounds and topics SwissBorg candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the SwissBorg loop
- Write out the reported sequence: Application Review, Technical Take-home Assignment, Behavioral Interview, Executive-level Conversations, Feedback and 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.
02Work Technical Challenge / Take-home Assignment
- Spend the session on Technical Challenge / Take-home Assignment, which SwissBorg candidates report being tested on.
- Write one worked example in Technical Challenge / Take-home Assignment and time yourself on it.
Deliverable: One timed worked example in Technical Challenge / Take-home Assignment.
03Work Recruitment Process (Multi-stage interviewing)
- Spend the session on Recruitment Process (Multi-stage interviewing), which SwissBorg candidates report being tested on.
- Write one worked example in Recruitment Process (Multi-stage interviewing) and time yourself on it.
Deliverable: One timed worked example in Recruitment Process (Multi-stage interviewing).
04Work Technical Interview (Live)
- Spend the session on Technical Interview (Live), which SwissBorg candidates report being tested on.
- Write one worked example in Technical Interview (Live) and time yourself on it.
Deliverable: One timed worked example in Technical Interview (Live).
05Answer out loud: Scala & Functional Programming
- Answer aloud, timed: Explain the difference between `Future` and task-based effects (like Cats Effect or ZIO) in Scala.
- Answer aloud, timed: How does the Akka/Pekko actor model handle state, concurrency, and fault tolerance?
Deliverable: Spoken answers to 2 reported Scala & Functional Programming question(s), under time.
06Answer out loud: Distributed Systems & Architecture
- Answer aloud, timed: How would you design a distributed transaction system that guarantees "exactly-once" processing?
- Answer aloud, timed: Explain how you would implement a rate-limiting mechanism for our public APIs.
Deliverable: Spoken answers to 2 reported Distributed Systems & Architecture question(s), under time.
07Answer out loud: Behavioral & Crypto Ecosystem
- Answer aloud, timed: Why are you interested in the crypto and Web3 space, and what is your outlook on decentralized finance?
- Answer aloud, timed: Describe a time when you had to make a technical compromise to meet a tight deadline. How did you manage technical debt?
Deliverable: Spoken answers to 2 reported Behavioral & Crypto Ecosystem 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.
Why are you interested in the crypto and Web3 space, and what is your outlook on decentralized finance?
Why are you interested in the crypto and Web3 space, and what is your outlook on decentralized finance?
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 when you had to make a technical compromise to meet a tight deadline. How did you manage techn
Describe a time when you had to make a technical compromise to meet a tight deadline. How did you manage technical debt?
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 constructive feedback from peers during a challenging code review?
How do you handle constructive feedback from peers during a challenging code review?
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?
Tell me about a complex technical problem you solved. How did you explain it to non-technical stakeholders?
Tell me about a complex technical problem you solved. How did you explain it to non-technical stakeholders?
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 stay updated with the latest trends and security vulnerabilities in the blockchain and backend engi
How do you stay updated with the latest trends and security vulnerabilities in the blockchain and backend engineering space?
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
Why are you interested in the crypto and Web3 space, and what is your outlook on decentralized finance?
- 02
Describe a time when you had to make a technical compromise to meet a tight deadline. How did you manage technical debt?
- 03
How do you handle constructive feedback from peers during a challenging code review?
- 04
Tell me about a complex technical problem you solved. How did you explain it to non-technical stakeholders?
What is the technical stack used by the SwissBorg engineering team?
The backend is primarily built using Scala, leveraging libraries and frameworks such as Akka/Pekko, Cats, and ZIO. They run a microservices architecture deployed on AWS using Kubernetes, with Kafka utilized for event streaming.
SwissBorg Software Engineer candidate reports ↗How deep does my crypto knowledge need to be to get hired?
You do not need to be a blockchain protocol engineer, but you must have a solid understanding of how the crypto ecosystem works and a genuine passion for the industry. The CEO round, in particular, will test your interest in Web3 and decentralized finance.
SwissBorg Software Engineer candidate reports ↗Is SwissBorg fully remote, and are there any location restrictions?
While SwissBorg supports remote work, they have strict legal and operational boundaries regarding where they can hire. They practice location-based salary adjustments, and they may not be able to hire in certain countries even if a job posting is listed as remote. Always clarify your location eligibility during your initial HR screening.
SwissBorg Software Engineer candidate reports ↗How difficult is the take-home assignment?
The assignment is of average difficulty and is designed to take a few hours. It focuses on writing clean, functional code to solve a practical problem. The real test is how well you present and defend your design choices during the follow-up technical interview. ##### Tip If you do not receive feedback within 5-7 business days after submitting your coding challenge, do not hesitate to send a polite follow-up email to your HR contact.
SwissBorg Software Engineer candidate reports ↗What topics does SwissBorg test in interviews?
SwissBorg interviews most often cover Technical Challenge / Take-home Assignment, Recruitment Process (Multi-stage interviewing), Technical Interview (Live), Behavioral Interview, and HR Screening. The exact emphasis depends on the specific role you apply for.
SwissBorg 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.
- 01SwissBorg 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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