As a Software Engineer at Ookla, you will play a pivotal role in developing and maintaining the technologies that power the company's flagship products, such as Speedtest and Ookla's Network Diagnostic tools. Your work will directly impact users' experiences by ensuring that they receive accurate, reliable, and fast assessments of their internet performance. This position is not only about writing code; it's about solving complex problems at scale and contributing to a team that prioritizes innovation and quality. The role is critical as it connects various aspects of technology, user needs, and business objectives. As a part of the engineering team, you will engage with cross-functional partners—like product managers and designers—to create features that enhance user satisfaction and broaden the reach of Ookla's services. You will encounter challenges related to high traffic volumes, data integrity, and performance optimization, making this role both interesting and rewarding.
Recruiter Call
reportedInitial screening call with a recruiter to discuss your background and the role's requirements.
What to demonstrate
- Initial screening call with a recruiter to discuss your background and the role's requirements
- Depth in Coding proficiency (general)
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 Interview
reportedInterview assessing your coding skills through practical challenges.
What to demonstrate
- Interview assessing your coding skills through practical challenges
- Depth in Coding proficiency (general)
How to prepare
- Answer aloud and timed: What are the principles of RESTful API design?
- Answer aloud and timed: Describe how you would handle concurrency in a multi-threaded application.
Behavioral Assessments
reportedInterviews focusing on your behavioral fit and cultural alignment with Ookla.
What to demonstrate
- Interviews focusing on your behavioral fit and cultural alignment with Ookla
- Depth in Coding proficiency (general)
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 assessments above and write down what you would ask to confirm before it.
Deeper Technical Discussions
reportedIn-depth technical interviews covering advanced topics and problem-solving.
What to demonstrate
- In-depth technical interviews covering advanced topics and problem-solving
- Depth in Coding proficiency (general)
How to prepare
- Answer aloud and timed: How would you implement a binary search algorithm?
- Answer aloud and timed: Can you explain the time complexity of your solution?
PracHub editorial advice for the preparation topics above.
Practice coding questions
Regularly solve coding challenges on platforms like LeetCode or HackerRank to sharpen your skills.
Understand the company’s products
Familiarize yourself with Ookla's offerings, especially Speedtest, to demonstrate your interest and understanding during interviews.
Be prepared for behavioral questions
Reflect on past experiences that showcase your skills and alignment with Ookla's values.
Communicate clearly
During technical interviews, explain your thought process as you solve problems. This will help interviewers understand your approach.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Describe how you would handle concurrency in a multi-threaded application.
Describe how you would handle concurrency in a multi-threaded 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?
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?
How would you implement a binary search algorithm?
How would you implement a binary search algorithm?
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 explain the time complexity of your solution?
Can you explain the time complexity of your solution?
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?
Describe how you would find the longest substring without repeating characters.
Describe how you would 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?
Write a program to merge two sorted arrays.
Write a program to merge two sorted arrays.
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?
How do you optimize a slow-running SQL query?
How do you optimize a slow-running SQL query?
Approach
- Name the grain you start from and join outward from it.
- Check whether any join is one-to-many before aggregating, or the sums inflate.
- Say which index the query would use, and what makes it unusable.
- Handle the rows that do not match: that is usually the actual question.
Follow-up
- How does the query change if that join becomes one-to-many?
- What happens to this when the table is ten times larger?
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 the difference between a stack and a queue.
Explain the difference between a stack and a queue.
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 the principles of RESTful API design?
What are the principles of RESTful API design?
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?
What is the purpose of indexing in a database?
What is the purpose of indexing in a database?
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?
Describe a situation where you had to make a difficult technical decision.
Describe a situation where you had to make a difficult technical decision.
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 steps would you take to gather requirements for a new feature?
What steps would you take to gather requirements for a new feature?
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 the quality of your code?
How do you ensure the quality of your 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?
Design a URL shortening service. What components would you include?
Design a URL shortening service. What components would you include?
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 architect a system to handle millions of users?
How would you architect a system to handle millions of users?
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 design a real-time chat application.
Explain how you would design a real-time chat 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?
Discuss how you would approach scaling a web application.
Discuss how you would approach scaling 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?
How would you approach debugging a performance issue in a production environment?
How would you approach debugging a performance issue in a production environment?
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 Ookla candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Ookla loop
- Write out the reported sequence: Recruiter Call, Technical Interview, Behavioral Assessments, Deeper Technical 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 Coding proficiency (general)
- Spend the session on Coding proficiency (general), which Ookla candidates report being tested on.
- Write one worked example in Coding proficiency (general) and time yourself on it.
Deliverable: One timed worked example in Coding proficiency (general).
03Work Technical interview (coding skills threshold)
- Spend the session on Technical interview (coding skills threshold), which Ookla candidates report being tested on.
- Write one worked example in Technical interview (coding skills threshold) and time yourself on it.
Deliverable: One timed worked example in Technical interview (coding skills threshold).
04Work Logical reasoning
- Spend the session on Logical reasoning, which Ookla candidates report being tested on.
- Write one worked example in Logical reasoning and time yourself on it.
Deliverable: One timed worked example in Logical reasoning.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: Explain the difference between a stack and a queue.
- Answer aloud, timed: How do you optimize a slow-running SQL query?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: Coding / Algorithms
- Answer aloud, timed: Write a function to reverse a linked list.
- Answer aloud, timed: How would you implement a binary search algorithm?
Deliverable: Spoken answers to 2 reported Coding / Algorithms question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Describe a challenging project you worked on. What was your role?
- Answer aloud, timed: How do you prioritize tasks when facing 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.
Describe a challenging project you worked on. What was your role?
Describe a challenging project you worked on. What was your role?
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 facing tight deadlines?
How do you prioritize tasks when facing 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?
Give an example of how you handled a conflict within a team.
Give an example of how you handled a conflict within a 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?
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?
Explain a time when you had to learn a new technology quickly.
Explain a time when you had to learn a new technology quickly.
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 a challenging project you worked on. What was your role?
- 02
How do you prioritize tasks when facing tight deadlines?
- 03
Give an example of how you handled a conflict within a team.
- 04
What motivates you to work in software engineering?
How difficult are the interviews at Ookla?
The interviews are designed to be challenging but fair. Candidates should expect a mix of technical and behavioral questions that test their knowledge and fit for the role.
Ookla Software Engineer candidate reports ↗What differentiates successful candidates?
Successful candidates demonstrate strong technical skills, clear communication, and a collaborative mindset. They align well with Ookla's values and show a commitment to quality in their work.
Ookla Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
The process can vary, but candidates often receive feedback within a few weeks after their final interview. Stay proactive in following up with your recruiter for updates.
Ookla Software Engineer candidate reports ↗How does remote work fit into the company culture?
Ookla supports flexible work arrangements and values productivity over location. Ensure you express your adaptability and comfort with remote collaboration.
Ookla Software Engineer candidate reports ↗What is the culture and working style at Ookla?
The culture at Ookla is characterized by innovation, teamwork, and a focus on delivering high-quality products. Employees are encouraged to collaborate and share ideas freely.
Ookla Software Engineer candidate reports ↗What topics does Ookla test in interviews?
Ookla interviews most often cover Problem solving, Communication, Stakeholder Management, Engineering Management, and Customer success engineering. The exact emphasis depends on the specific role you apply for.
Ookla 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.
- 01Ookla 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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