A Software Engineer at Stone is a core builder of the financial technology infrastructure that powers millions of merchants across Brazil. Stone has evolved far beyond a simple card-processing company; it is a massive tech ecosystem encompassing payments, banking, credit, and specialized software solutions. As an engineer here, you will design, deploy, and scale high-throughput systems where low latency, high availability, and absolute correctness are non-negotiable. Your work will directly impact the daily operations of Brazilian entrepreneurs. Whether you are optimizing transaction processing pipelines, building robust APIs, integrating generative AI chatbots, or scaling mobile payment applications, you will solve complex distributed systems problems. You will work within highly collaborative, cross-functional teams that utilize agile methodologies to deliver continuous value through rapid, incremental releases. Stone operates with a tech-first mindset, deploying advanced cloud infrastructures, modern microservices, and event-driven architectures. Engineers are expected to possess not only strong coding capabilities but also a deep sense of ownership. You will be encouraged to experiment, learn from failures, and continuously raise the bar for engineering excellence across the entire organization.
Recruiter Conversation
reportedInitial conversation with a recruiter to align expectations and assess general fit.
What to demonstrate
- Initial conversation with a recruiter to align expectations and assess general fit
- 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 Stages
reportedOne or two technical rounds focusing on coding abilities, system design knowledge, and past project experiences.
What to demonstrate
- One or two technical rounds focusing on coding abilities, system design knowledge, and past project experiences
- Depth in System Design
How to prepare
- Answer aloud and timed: Given an array of integers, find the contiguous subarray which has the largest sum and return its sum.
- Answer aloud and timed: Reverse a linked list iteratively and recursively, explaining the trade-offs of each approach.
Cultural Fit Interview
reportedInterview to ensure your working style aligns with Stone's core organizational values.
What to demonstrate
- Interview to ensure your working style aligns with Stone's core organizational values
- Depth in System Design
How to prepare
- Answer aloud and timed: Explain how you would implement a queue using two stacks.
- Answer aloud and timed: Design a URL shortener service like Bitly, focusing on high-read throughput and database selection.
1 candidate reports. Individual accounts describe a particular role and hiring cycle.
Stone Data Analyst interview: approved, then left waiting for months
I had a very quick conversation with HR, then was told I had passed and should wait for the position to open. The offer seemed clear and matched the job description. The interview itself was objective and respectful, with questions that fit the role, and the timeline was within what they had indicated. I felt calm about it. What knocked the wind out of me was everything after that. I had supposed…
Read full experiencePracHub editorial advice for the preparation topics above.
Going into the loop without having done this.
Communicate your thought process: During both coding and system design interviews, talk through your reasoning. Explain the trade-offs of the solutions you consider, as interviewers value your problem-solving approach just as much as the final output.
Going into the loop without having done this.
Structure your behavioral answers: Use the STAR method (Situation, Task, Action, Result) to keep your responses concise, structured, and focused on your personal contributions and the impact of your actions.
Going into the loop without having done this.
Showcase your curiosity: Don't hesitate to ask thoughtful questions about Stone's engineering culture, technical challenges, and team structure at the end of your interviews. It demonstrates genuine interest and engagement.
Going into the loop without having done this.
Do not attempt to overcomplicate your system designs. Focus on simplicity first, and only introduce complex architectures (like microservices or event streaming) when the scale or business requirements genuinely justify them.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function to determine if a string has all unique characters, optimizing for both time and space comple
Write a function to determine if a string has all unique characters, optimizing for both time and space 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?
Given an array of integers, find the contiguous subarray which has the largest sum and return its sum.
Given an array of integers, find the contiguous subarray which has the largest sum and return its sum.
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?
Reverse a linked list iteratively and recursively, explaining the trade-offs of each approach.
Reverse a linked list iteratively and recursively, explaining the trade-offs of each approach.
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 implement a queue using two stacks.
Explain how you would implement a queue using two stacks.
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 the difference between optimistic and pessimistic locking, and how they prevent race conditions.
Explain the difference between optimistic and pessimistic locking, and how they prevent race conditions.
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 is the difference between SQL and NoSQL databases, and when would you choose one over the other for a fin
What is the difference between SQL and NoSQL databases, and when would you choose one over the other for a financial ledger?
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?
Explain the concepts of database indexing and how an improper index can degrade write performance.
Explain the concepts of database indexing and how an improper index can degrade write performance.
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?
Implement a basic rate limiter for an API endpoint using an algorithm of your choice.
Implement a basic rate limiter for an API endpoint using an algorithm of your choice.
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?
Design a URL shortener service like Bitly, focusing on high-read throughput and database selection.
Design a URL shortener service like Bitly, focusing on high-read throughput and database selection.
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 real-time notification system that handles millions of push notifications and SMS me
How would you architect a real-time notification system that handles millions of push notifications and SMS messages daily?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
Design the backend architecture for a payment gateway, ensuring transaction consistency and handling network t
Design the backend architecture for a payment gateway, ensuring transaction consistency and handling network timeouts gracefully.
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 structure a chat application's backend to support offline messaging and synchronization?
How would you structure a chat application's backend to support offline messaging and synchronization?
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 transition a monolithic application to a microservices architecture using message broker
Explain how you would transition a monolithic application to a microservices architecture using message brokers like Kafka or SQS.
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 implement observability and tracing in a microservices environment? What metrics are critical to mo
How do you implement observability and tracing in a microservices environment? What metrics are critical to monitor?
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 ensure secure communication between internal microservices?
How do you ensure secure communication between internal microservices?
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?
Exports duplicate a row range about once a week
Roughly once a week an export writes a file containing a duplicated range of rows. The affected job_run rows show attempt = 1, status = succeeded, one started_at, and a lease_owner naming a different host from the one whose logs show the job starting. Leases last 30 seconds and are heartbeated every 10 from inside the handler; lease_expires_at is computed on the worker and compared against the database's now(). Find the mechanism, and give a fix that holds even if you cannot fix the clocks.
Approach
- Start from the fact that eliminates the obvious answer. attempt = 1 means no retry was recorded, so this is not a re-run after failure; two workers ran the same row concurrently and the takeover path never touched the counter. lease_owner naming a host other than the one that started the job is the same statement from the other side.
- Enumerate the mechanisms that cause a premature takeover, then find the signal that separates them. Either the lease genuinely expired because the heartbeat did not fire, which is what happens when the heartbeat runs on the handler's own thread and the handler makes a long blocking call, or it only appeared expired because two clocks disagree, since lease_expires_at is written from the worker's clock and evaluated against the database's. The discriminator is the distribution: incidents clustered on the longest exports indict the heartbeat, incidents clustered on one host indict skew. Measure both, and measure each host's offset against the database directly.
- Read the reclaim query precisely. In PostgreSQL now() is transaction start time, not statement time, so a reclaimer holding a long transaction compares against an older timestamp than expected; clock_timestamp() is the statement-time function. This is worth ruling in or out before you redesign anything, because it changes which rows look expired.
- Remove the second clock rather than trying to synchronise it. Issue and extend the lease in the database, with lease_expires_at = now() + interval '30 seconds' in both the claim and the heartbeat, so exactly one clock is ever compared and worker skew stops mattering to this predicate.
Follow-up
- The displaced worker has already streamed half the file to object storage. What makes that side effect safe to repeat?
- You now count takeovers. What alert fires on that counter, and at what threshold?
Built from the rounds and topics Stone candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the Stone loop
- Write out the reported sequence: Recruiter Conversation, Technical Stages, Cultural Fit Interview.
- 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 Stone 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 Arquitetura de software
- Spend the session on Arquitetura de software, which Stone candidates report being tested on.
- Write one worked example in Arquitetura de software and time yourself on it.
Deliverable: One timed worked example in Arquitetura de software.
04Work Kotlin
- Spend the session on Kotlin, which Stone candidates report being tested on.
- Write one worked example in Kotlin and time yourself on it.
Deliverable: One timed worked example in Kotlin.
05Answer out loud: Coding and Algorithms
- Answer aloud, timed: Write a function to determine if a string has all unique characters, optimizing for both time and space complexity.
- Answer aloud, timed: Implement a basic rate limiter for an API endpoint using an algorithm of your choice.
Deliverable: Spoken answers to 2 reported Coding and Algorithms question(s), under time.
06Answer out loud: System Design and Architecture
- Answer aloud, timed: Design a URL shortener service like Bitly, focusing on high-read throughput and database selection.
- Answer aloud, timed: How would you architect a real-time notification system that handles millions of push notifications and SMS messages daily?
Deliverable: Spoken answers to 2 reported System Design and Architecture question(s), under time.
07Answer out loud: Technical Concepts and Domain Knowledge
- Answer aloud, timed: What is the difference between SQL and NoSQL databases, and when would you choose one over the other for a financial ledger?
- Answer aloud, timed: Explain the concepts of database indexing and how an improper index can degrade write performance.
Deliverable: Spoken answers to 2 reported Technical Concepts and Domain Knowledge 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 time when you made a technical decision that resulted in a failure. How did you handle it, and what
Describe a time when you made a technical decision that resulted in a failure. How did you handle it, and what did you learn?
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 a situation where you disagree with a product manager or a tech lead on a technical approach
How do you handle a situation where you disagree with a product manager or a tech lead on a technical approach?
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 project you owned from start to finish. How did you manage stakeholders and ensure del
Tell me about a complex project you owned from start to finish. How did you manage stakeholders and ensure delivery?
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 mentored a junior engineer or helped improve your team's overall engineering practi
Give an example of how you mentored a junior engineer or helped improve your team's overall engineering practices.
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 technical debt versus delivering new features under tight deadlines?
How do you prioritize technical debt versus delivering new features under 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
Describe a time when you made a technical decision that resulted in a failure. How did you handle it, and what did you learn?
- 02
How do you handle a situation where you disagree with a product manager or a tech lead on a technical approach?
- 03
Tell me about a complex project you owned from start to finish. How did you manage stakeholders and ensure delivery?
- 04
Give an example of how you mentored a junior engineer or helped improve your team's overall engineering practices.
What is the primary tech stack used by software engineering teams at Stone?
Stone utilizes a diverse set of technologies across different business units. The primary backend stacks include Node.js/TypeScript, Python, C#, and Elixir. Mobile teams typically work with Kotlin (including Kotlin Multiplatform), Swift, and React Native.
Stone Software Engineer candidate reports ↗How should I prepare for the coding interview if I am rusty in a specific language?
It is highly recommended to practice solving algorithmic challenges on platforms like LeetCode in the language you feel most comfortable with. Ensure you can write clean, syntactically correct code without relying heavily on IDE auto-complete features, as some interview environments do not support them.
Stone Software Engineer candidate reports ↗How long does the entire interview process take from start to finish?
The duration of the process can vary, but Stone is known for its agility. On average, the process takes between 2 to 4 weeks. The recruitment team generally keeps candidates informed about timelines and next steps throughout the journey.
Stone Software Engineer candidate reports ↗Does Stone offer remote work opportunities for software engineers?
Yes, Stone offers various work models, including fully remote positions within Brazil, hybrid roles (such as in Florianópolis, Rio de Janeiro, or São Paulo), and office-based positions, depending on the specific team and project requirements.
Stone Software Engineer candidate reports ↗How hard is the Stone interview?
Candidates most commonly rate Stone interviews as medium, based on 514 reported interviews. About 37% of candidates who interview go on to receive an offer.
Stone Software Engineer candidate reports ↗What topics does Stone test in interviews?
Stone interviews most often cover Problem Solving, Communication Skills, Analytical Thinking, Data Interpretation, and B2B Sales. The exact emphasis depends on the specific role you apply for.
Stone Software Engineer candidate reports ↗Where is Stone headquartered?
Stone is headquartered in São Paulo, Brazil.
Stone Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
Official role evidence, timestamped platform data and clearly labeled preparation advice.
- 01Stone Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
candidate · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
platform · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
platform · Accessed 2026-09-22
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