SIXT · Software Engineer
Updated · 2026-10-02

SIXT Software Engineer
Interview Guide

THE 60-SECOND BRIEF

A Software Engineer at SIXT is responsible for designing, developing, and scaling the core systems that power one of the world's leading mobility providers. From real-time vehicle booking engines and dynamic pricing algorithms to global fleet management and payment integrations, engineering teams at SIXT solve complex physical-to-digital challenges. The code you write directly impacts millions of customers worldwide, ensuring seamless rental, ride-sharing, and car subscription services. Operating at high scale, the engineering culture at SIXT emphasizes microservices, cloud-native architectures, and robust data pipelines. You will work in a highly collaborative environment where software development is viewed as a craft.

This guide is scoped to a Software Engineer candidate at SIXT.

SIXT candidates report 4 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Data Structures & Algorithms (DSA)System Design (Scalability/Architecture focus)JavaScript (JS)

21 min read

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1Candidate experiences ↗Read their reports
18Practice promptsAcross five skill areas

A Software Engineer at SIXT is responsible for designing, developing, and scaling the core systems that power one of the world's leading mobility providers. From real-time vehicle booking engines and dynamic pricing algorithms to global fleet management and payment integrations, engineering teams at SIXT solve complex physical-to-digital challenges. The code you write directly impacts millions of customers worldwide, ensuring seamless rental, ride-sharing, and car subscription services. Operating at high scale, the engineering culture at SIXT emphasizes microservices, cloud-native architectures, and robust data pipelines. You will work in a highly collaborative environment where software development is viewed as a craft. Engineers are expected to take complete ownership of their services, from initial design and local development to deployment in production environments using modern DevOps toolchains. Whether you are optimizing backend services in Munich or building frontend interfaces in Bengaluru, your work directly influences the company's digital transformation. The systems you build must remain highly available, secure, and low-latency, navigating the unique challenges of real-time supply and demand in the global transportation market.

The SIXT interview process

01

Initial Screening

reported

Includes a brief call with a recruiter followed by an online coding assessment.

What to demonstrate

  • Includes a brief call with a recruiter followed by an online coding assessment
  • Depth in Data Structures & Algorithms (DSA)

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.
SIXT Software Engineer candidate reports ↗
02

Online Coding Assessment

reported

Tests your algorithmic thinking and core programming skills under timed conditions.

What to demonstrate

  • Tests your algorithmic thinking and core programming skills under timed conditions
  • Depth in Data Structures & Algorithms (DSA)

How to prepare

  • Answer aloud and timed: Implement an optimized pagination algorithm in Python or JavaScript for handling millions of records.
  • Answer aloud and timed: Solve a dynamic programming problem involving array manipulation or resource allocation.
SIXT Software Engineer candidate reports ↗
03

Technical Interviews

reported

Focus on live coding, system design, and computer science fundamentals.

What to demonstrate

  • Focus on live coding, system design, and computer science fundamentals
  • Depth in Data Structures & Algorithms (DSA)

How to prepare

  • Answer aloud and timed: Implement a queue using stacks and discuss the amortized cost of operations.
  • Answer aloud and timed: Design a high-performance carousel component for a web application, detailing how you handle Server-Side Rendering (SSR) and hydration.
SIXT Software Engineer candidate reports ↗
04

Behavioral Discussions

reported

Evaluate team fit and leadership potential with hiring managers and directors.

What to demonstrate

  • Evaluate team fit and leadership potential with hiring managers and directors
  • Depth in Data Structures & Algorithms (DSA)

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 discussions above and write down what you would ask to confirm before it.
SIXT Software Engineer candidate reports ↗

From candidates who interviewed

1 candidate reports. Individual accounts describe a particular role and hiring cycle.

Software Engineer

SIXT Software Engineer interview: campus DSA cutoff

Online Assessment → Technical Screen → HR ScreenOutcome: rejected

The campus drive began with an online assessment containing two medium LeetCode-style coding questions. About 20 of roughly 150 students were shortlisted for interviews. My first technical round covered time and space complexity and a medium dynamic-programming LeetCode problem. I did not make it past that first technical interview. Candidates who did move on had a second interview, and a smaller…

Read full experience

Where candidates lose points

PracHub editorial advice for the preparation topics above.

01

Write complete, optimized code

During coding rounds, interviewers value clean syntax and fully realized logic. Avoid relying heavily on pseudo-code unless explicitly permitted by your interviewer.

02

Deep dive into your resume

Be ready to explain the architecture, trade-offs, and business impact of the projects listed on your resume. Interviewers will ask detailed questions about your technical decisions.

03

Clarify requirements early

Before writing any code or drawing an architecture diagram, ask clarifying questions to establish constraints, input/output formats, and edge cases.

04

Some candidates have reported delays in communication during the final stages of the process

If you do not hear back within a few business days after a round, do not hesitate to reach out to your recruiter for an update.

Questions & practice

Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.

15 technical prompts0 include a worked solution

Reverse a singly linked list in-place and explain the time and space complexity.

medium
Data Structures & Algorithms

Reverse a singly linked list in-place and explain the time and space complexity.

Approach
  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. 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 the height of a binary tree and write a function to delete a node from it.

medium
Data Structures & Algorithms

Find the height of a binary tree and write a function to delete a node from it.

Approach
  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. 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?

Solve a dynamic programming problem involving array manipulation or resource allocation.

medium
Data Structures & Algorithms

Solve a dynamic programming problem involving array manipulation or resource allocation.

Approach
  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. 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 queue using stacks and discuss the amortized cost of operations.

medium
Data Structures & Algorithms

Implement a queue using stacks and discuss the amortized cost of operations.

Approach
  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. 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 constructors and destructors handle memory management in multi-threaded environments?

medium
Language-Specific & CS Fundamentals

How do constructors and destructors handle memory management in multi-threaded environments?

Approach
  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. 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?

Describe how concurrency and multi-threading are handled in Java or JavaScript, and how to prevent deadlocks.

medium
Language-Specific & CS Fundamentals

Describe how concurrency and multi-threading are handled in Java or JavaScript, and how to prevent deadlocks.

Approach
  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. 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?

Suggested practice checklist

Built from the rounds and topics SIXT candidates report.

Small steps. Visible outcomes.0 / 7 completed
ONE WEEK · YOUR PACE

Prepare, practise & reflect

One practical outcome each day. Spend longer where you need it.

0 / 7 done
01Map the SIXT loop
  • Write out the reported sequence: Initial Screening, Online Coding Assessment, Technical Interviews, Behavioral 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 Data Structures & Algorithms (DSA)
  • Spend the session on Data Structures & Algorithms (DSA), which SIXT candidates report being tested on.
  • Write one worked example in Data Structures & Algorithms (DSA) and time yourself on it.

Deliverable: One timed worked example in Data Structures & Algorithms (DSA).

03Work System Design (Scalability/Architecture focus)
  • Spend the session on System Design (Scalability/Architecture focus), which SIXT candidates report being tested on.
  • Write one worked example in System Design (Scalability/Architecture focus) and time yourself on it.

Deliverable: One timed worked example in System Design (Scalability/Architecture focus).

04Work JavaScript (JS)
  • Spend the session on JavaScript (JS), which SIXT candidates report being tested on.
  • Write one worked example in JavaScript (JS) and time yourself on it.

Deliverable: One timed worked example in JavaScript (JS).

05Answer out loud: Data Structures & Algorithms
  • Answer aloud, timed: Reverse a singly linked list in-place and explain the time and space complexity.
  • Answer aloud, timed: Find the height of a binary tree and write a function to delete a node from it.

Deliverable: Spoken answers to 2 reported Data Structures & Algorithms question(s), under time.

06Answer out loud: System Design & Architecture
  • Answer aloud, timed: Design a high-performance carousel component for a web application, detailing how you handle Server-Side Rendering (SSR) and hydration.
  • Answer aloud, timed: How would you design a distributed caching layer using Redis to reduce database load for a high-traffic booking system?

Deliverable: Spoken answers to 2 reported System Design & Architecture question(s), under time.

07Answer out loud: Language-Specific & CS Fundamentals
  • Answer aloud, timed: Explain the difference between Redux and the React Context API, specifically addressing state rehydration on the client.
  • Answer aloud, timed: How do constructors and destructors handle memory management in multi-threaded environments?

Deliverable: Spoken answers to 2 reported Language-Specific & CS Fundamentals question(s), under time.

Expand any day for tasks and deliverables. Your progress is saved on this device.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Reverse your own decision and price the reversal

medium
reversibilitymeasurementmigrations

Describe a technical decision you made and later reversed. Pick one that cost something: a service you split and merged back, a cache you added and removed, an index you created that pushed the planner onto a worse plan, a projection you rebuilt from scratch. State what you believed when you decided, the measurement that changed your mind, how long the wrong version ran in production, and what the reversal cost in migrations, dual writes, and a deprecation window for callers you did not own.

Approach
  1. State the original rationale without irony, in the version you would still defend given what was known then. If it is not defensible, the story is about carelessness rather than judgement, and a different example serves you better.
  2. Give the measurement that moved with a before and after: the p99 that did not improve, the cache hit rate that sat at 40%, the plan that flipped to a sequential scan once the table passed a size you can name.
  3. Cost the reversal in steps, not adjectives: expand-and-contract deploys, the dual-write window, the callers who had to be notified, the rows already written in the wrong shape that had to be backfilled or abandoned.
  4. Distinguish reversal from rewrite by naming what you kept. Most good reversals preserve the schema or the interface and undo one decision inside it, which is also why they were affordable.
Follow-up
  • What in that decision was irreversible, and did you know it was irreversible when you made it?
  • How did you tell the people who had already built on top of the original decision?

Unblock an engineer without taking the keyboard

easy
mentoringleasesat-least-once

A teammate has spent two days on a job handler that occasionally writes duplicate rows. They are certain the queue is delivering twice by mistake. You suspect a lease expiring under a slow handler, so the job is running concurrently with itself. Describe how you have unblocked someone in this position: what you asked before offering a hypothesis, what you showed them rather than told them, and what you left them owning. Then say what you would do if their theory turned out to be the right one.

Approach
  1. Ask before diagnosing, and ask for things answerable from data they already have: the attempt count on the job rows that produced duplicates, the handler's observed duration against its lease expiry, and whether the duplicate rows share a natural key that a unique constraint could have caught.
  2. Teach the shape rather than the answer. A lease cannot distinguish a dead worker from a slow one, so a handler that outruns its lease is running twice by design, and deploys deliver the other half by killing handlers mid-run on every rollout. Both of their candidate theories produce identical duplicate rows, which is why the evidence has to come from timings rather than from argument.
  3. Hand over a checklist they execute: a natural key on every write the handler performs so the second copy collides rather than appends, the record of intent written before any external effect, a lease heartbeat while running, and the metric that shows it working.
  4. Keep ownership with them deliberately. Pair on the first write, then step back; if you finish it yourself you have closed one ticket and left the same person stuck on the next redelivery.
Follow-up
  • How would you distinguish a genuine double-delivery from a lease expiry using only the data already stored?
  • Their handler calls an external endpoint before recording that it did. What do you tell them to change first?

Ship under a deadline and bound the debt you chose

medium
paginationtechnical debttradeoffs

You have four days to ship a tenant-facing listing endpoint. The version you would defend uses keyset pagination over (tenant_id, status, updated_at DESC, resource_id DESC); the version you can finish uses LIMIT/OFFSET with no matching index. Describe a deadline call you actually made of this shape: what you shipped, what you knowingly deferred, how you bounded the damage with a mechanism rather than an intention, and the specific numeric condition that would force the follow-up. Name who you told and where you wrote it down.

Approach
  1. Name the deferred failure precisely instead of calling it slow. OFFSET n makes the database produce and discard n rows, so cost grows with page depth; without an index matching the sort, every matching row is read and sorted before the limit applies; and rows inserted between two page fetches shift across the boundary so items are skipped or repeated with nothing in the response to signal it.
  2. Bound the blast radius with something mechanical rather than a promise: cap maximum page depth, cap page size, restrict the endpoint to one internal caller, or keep it behind a flag. State which failure each cap removes and which it leaves standing.
  3. Attach a number to the trigger and wire it to an alarm: the first tenant crossing N resources, or the endpoint's p99 crossing its share of the 400 ms budget, so the debt announces itself instead of waiting to be remembered.
  4. Write it where the next engineer looks, which is the code and the ticket, not a chat message: what was deferred, why, the cap, and the trigger.
Follow-up
  • At what page depth does the offset version breach your latency budget, given your page size and row counts?
  • What breaks first when you switch to keyset pagination later, and what does a client holding an old page token see?
  • 01

    Describe a technical decision you made and later reversed. Pick one that cost something: a service you split and merged back, a cache you added and removed, an index you created that pushed the planner onto a worse plan, a projection you rebuilt from scratch. State what you believed when you decided, the measurement that changed your mind, how long the wrong version ran in production, and what the reversal cost in migrations, dual writes, and a deprecation window for callers you did not own.

  • 02

    A teammate has spent two days on a job handler that occasionally writes duplicate rows. They are certain the queue is delivering twice by mistake. You suspect a lease expiring under a slow handler, so the job is running concurrently with itself. Describe how you have unblocked someone in this position: what you asked before offering a hypothesis, what you showed them rather than told them, and what you left them owning. Then say what you would do if their theory turned out to be the right one.

  • 03

    You have four days to ship a tenant-facing listing endpoint. The version you would defend uses keyset pagination over (tenant_id, status, updated_at DESC, resource_id DESC); the version you can finish uses LIMIT/OFFSET with no matching index. Describe a deadline call you actually made of this shape: what you shipped, what you knowingly deferred, how you bounded the damage with a mechanism rather than an intention, and the specific numeric condition that would force the follow-up. Name who you told and where you wrote it down.

PracHub preparation framework ↗

Frequently asked questions

What programming languages can I use during the technical interviews?

You can generally use the language you are most comfortable with, such as Java, Python, C++, or JavaScript. However, if you are interviewing for a highly specialized role, your interviewers may evaluate you on specific stack capabilities.

SIXT Software Engineer candidate reports ↗
How deep do the system design interviews go?

The system design rounds are highly comprehensive. You should be prepared to discuss high-level architecture, database schema design, API contracts, caching strategies, and how to handle system failures or sudden traffic spikes.

SIXT Software Engineer candidate reports ↗
What is the typical timeline from the first call to an offer?

The entire process typically takes between two to four weeks. However, coordination timelines can vary depending on the location, team, and the availability of interviewers.

SIXT Software Engineer candidate reports ↗
Are there behavioral rounds, and how should I prepare?

Yes, behavioral evaluation is integrated into the hiring manager and director rounds. Prepare to discuss your past projects, how you handle technical disagreements, and your experience working in fast-paced, agile environments using the STAR method.

SIXT Software Engineer candidate reports ↗
What topics does SIXT test in interviews?

SIXT interviews most often cover Java, Stakeholder Communication, Selenium, Problem Solving, and Python. The exact emphasis depends on the specific role you apply for.

SIXT 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.

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