The Software Engineer role at Uncountable is pivotal in driving the company's mission to reshape how data is utilized across various sectors. As a Software Engineer, you will be at the forefront of developing and optimizing the technological solutions that underpin our products, which cater to a range of industries including research, manufacturing, and analytics. Your contributions will significantly impact user experiences, product functionality, and overall business success. In this role, you will engage with complex data structures and algorithms, leveraging your technical expertise to design and implement scalable software solutions. You will collaborate closely with cross-functional teams, including product management and data science, to tackle challenging problems that enhance our suite of products. This position not only demands strong technical skills but also offers the opportunity to influence product direction and innovation within Uncountable. Expect to work on exciting projects that push the boundaries of what technology can achieve in data management and analysis. Your insights and contributions will help shape the future of our offerings, making this role both critical and rewarding.
Introductory Call
reportedAn initial call with a founder or senior team member to assess mutual fit in terms of values and expectations.
What to demonstrate
- An initial call with a founder or senior team member to assess mutual fit in terms of values and expectations
- Depth in SQL
How to prepare
- Answer aloud and timed: How do you approach debugging a complex issue in a large codebase?
- Answer aloud and timed: Describe your experience with data structures and algorithms. Can you provide an example where you applied them effectively?
Technical Interview
reportedA technical interview that includes coding exercises and problem-solving scenarios relevant to the Software Engineer role.
What to demonstrate
- A technical interview that includes coding exercises and problem-solving scenarios relevant to the Software Engineer role
- Depth in SQL
How to prepare
- Answer aloud and timed: What are the best practices for writing maintainable code?
- Answer aloud and timed: How do you prioritize technical debt in your projects?
Take-Home Assignment
reportedCandidates may be required to complete a take-home assignment testing practical skills in data manipulation or software design.
What to demonstrate
- Candidates may be required to complete a take-home assignment testing practical skills in data manipulation or software design
- Depth in SQL
How to prepare
- Answer aloud and timed: Explain a time when you had to learn a new technology quickly to meet a project requirement.
- Answer aloud and timed: Tell me about a time you faced a conflict in a team setting. How did you resolve it?
In-Depth Discussions
reportedFinal stages involve in-depth discussions with team members focusing on behavioral and cultural fit.
What to demonstrate
- Final stages involve in-depth discussions with team members focusing on behavioral and cultural fit
- Depth in SQL
How to prepare
- Answer aloud and timed: What motivates you to work in software engineering?
- Answer aloud and timed: Describe how you handle constructive criticism.
PracHub editorial advice for the preparation topics above.
Understand the Products
Familiarize yourself with Uncountable's products and services. This knowledge will help you relate your skills to the company's objectives.
Practice Coding
Engage in coding challenges that simulate real-world scenarios. Focus on writing efficient solutions and be prepared to discuss your thought process.
Prepare for Behavioral Questions
Reflect on your past experiences and be ready to discuss how they align with the company’s values and culture.
Ask Insightful Questions
Prepare thoughtful questions to ask your interviewers. This shows your interest in the role and can help you gauge if Uncountable is the right fit for you.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function to reverse a linked list.
Write a function to reverse a linked list.
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 a search algorithm for a sorted array.
Implement a search algorithm for a sorted array.
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?
Can you solve a problem that requires optimizing time complexity?
Can you solve a problem that requires optimizing time 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?
Explain how you would approach writing unit tests for your code.
Explain how you would approach writing unit tests for your code.
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?
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?
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?
What are the best practices for writing maintainable code?
What are the best practices for writing maintainable code?
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 do you prioritize technical debt in your projects?
How do you prioritize technical debt in your projects?
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?
Given a dataset with missing values, how would you handle the analysis?
Given a dataset with missing values, how would you handle the analysis?
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 system to track user interactions on a web application?
How would you design a system to track user interactions on a web application?
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 steps would you take to improve the performance of a slow-running application?
What steps would you take to improve the performance of a slow-running application?
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?
If you were asked to redesign an existing feature, what factors would you consider?
If you were asked to redesign an existing feature, what factors would you consider?
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?
Can you walk us through your approach to a recent project?
Can you walk us through your approach to a recent 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 do you ensure your code is efficient and scalable?
How do you ensure your code is efficient and scalable?
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 approach debugging a complex issue in a large codebase?
How do you approach debugging a complex issue in a large codebase?
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 Uncountable candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Uncountable loop
- Write out the reported sequence: Introductory Call, Technical Interview, Take-Home Assignment, In-Depth Discussions.
- 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 SQL
- Spend the session on SQL, which Uncountable candidates report being tested on.
- Write one worked example in SQL and time yourself on it.
Deliverable: One timed worked example in SQL.
03Work Data transformation / restructuring
- Spend the session on Data transformation / restructuring, which Uncountable candidates report being tested on.
- Write one worked example in Data transformation / restructuring and time yourself on it.
Deliverable: One timed worked example in Data transformation / restructuring.
04Work Excel / spreadsheet range operations
- Spend the session on Excel / spreadsheet range operations, which Uncountable candidates report being tested on.
- Write one worked example in Excel / spreadsheet range operations and time yourself on it.
Deliverable: One timed worked example in Excel / spreadsheet range operations.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: How do you approach debugging a complex issue in a large codebase?
- Answer aloud, timed: Describe your experience with data structures and algorithms. Can you provide an example where you applied them effectively?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Tell me about a time you faced a conflict in a team setting. How did you resolve it?
- Answer aloud, timed: What motivates you to work in software engineering?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
07Answer out loud: Problem-Solving / Case Studies
- Answer aloud, timed: Given a dataset with missing values, how would you handle the analysis?
- Answer aloud, timed: How would you design a system to track user interactions on a web application?
Deliverable: Spoken answers to 2 reported Problem-Solving / Case Studies 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.
Describe your experience with data structures and algorithms. Can you provide an example where you applied the
Describe your experience with data structures and algorithms. Can you provide an example where you applied them effectively?
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?
Explain a time when you had to learn a new technology quickly to meet a project requirement.
Explain a time when you had to learn a new technology quickly to meet a project requirement.
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 time you faced a conflict in a team setting. How did you resolve it?
Tell me about a time you faced a conflict in a team setting. How did you resolve it?
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?
What motivates you to work in software engineering?
What motivates you to work in software engineering?
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 how you handle constructive criticism.
Describe how you handle constructive criticism.
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?
Can you share an experience where you took the lead on a project?
Can you share an experience where you took the lead on a project?
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 ensure effective communication within your team?
How do you ensure effective communication within your team?
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
Describe your experience with data structures and algorithms. Can you provide an example where you applied them effectively?
- 02
Explain a time when you had to learn a new technology quickly to meet a project requirement.
- 03
Tell me about a time you faced a conflict in a team setting. How did you resolve it?
- 04
What motivates you to work in software engineering?
How difficult is the interview process for the Software Engineer role?
The interview process is generally considered average in difficulty, focusing on practical skills rather than theoretical knowledge. Candidates usually find the experience to be engaging, though it can vary depending on the interviewer.
Uncountable Software Engineer candidate reports ↗What differentiates successful candidates from others?
Successful candidates often demonstrate a strong alignment with Uncountable's values, possess solid technical skills, and exhibit effective problem-solving abilities. Being able to communicate clearly and work collaboratively also sets candidates apart.
Uncountable Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
The timeline can vary but typically spans 1-3 weeks from the initial screening call to the final decision. Candidates should expect prompt feedback after each interview stage.
Uncountable Software Engineer candidate reports ↗What is the culture like at Uncountable?
Uncountable fosters a culture of innovation and collaboration. Employees are encouraged to share ideas, take initiative, and contribute to a supportive team environment.
Uncountable Software Engineer candidate reports ↗Are there opportunities for remote work?
Uncountable supports a hybrid work model, allowing for flexibility in where you work while encouraging collaboration through regular team meetings and engagements.
Uncountable Software Engineer candidate reports ↗How many rounds is the Uncountable Software Engineer interview process?
Candidates report 4 stages: Introductory Call, Technical Interview, Take-Home Assignment, and In-Depth Discussions. The interview process section above breaks down what each stage covers.
Uncountable 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.
- 01Uncountable 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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