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Growth · Software Engineer Interview Guide

Interview language: English

How to Pass the 1KOMMA5° Software Engineer Interview in 2026

The 1KOMMA5° DNA (TL;DR)

1KOMMA5°'s 'Hand Heartbeat' principle guides assessments, seeking individuals who can drive the energy transition with practical impact. Interviewers look for tangible contributions to projects like Solaranlage Wie, demonstrating initiative and a clear vision for sustainable solutions.

The 1KOMMA5° Interview Loop

Your onsite loop will typically consist of 5 rounds.

1
Round 1
Recruiter Screen
Motivation, role fit, logistics.
2
Round 2
Coding Screen
LeetCode-medium algorithmic problems under time pressure.
3
Round 3
System Design
Distributed systems, trade-offs at scale, architecture under constraints.
4
Round 4
Onsite Coding
LeetCode-hard, debugging, code clarity, edge cases.
5
Round 5
Behavioral / Leadership
Past evidence of ownership, influence, resolving conflict.

The Danger Zone: Top Reasons Candidates Fail

Based on our database of 1KOMMA5° interview outcomes, avoid these common traps:

Becoming defensive or dismissive of the feedback.
Not handling edge cases like empty data or time ranges that fall between reported data points.
Describing a situation where the conflict was never resolved.
Claiming to know everything already or not identifying a specific learning need.

Test Yourself: Real 1KOMMA5° Questions

Three real prompts pulled from our database.

Type · algorithmic

Imagine you have a system that aggregates energy production data from solar panels across many households. Each household reports its production in kWh per minute. Write a function to calculate the total energy produced within a given time range (start_time, end_time) for a specific household, optimizing for performance when querying large datasets.

Type · learning

The energy sector is constantly evolving with new technologies and regulations. Can you give an example of a time you had to quickly learn a new technology or concept relevant to smart grids, renewable energy, or energy management systems for a project? How did you approach the learning process?

Type · architecture

1KOMMA5° is expanding its network of charging stations. Design a system to manage the charging status, availability, and billing for these stations. Consider how to handle concurrent charging sessions, potential hardware failures, and integration with payment gateways.

+ many more questions, signals, and worked examples

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1KOMMA5° Interview Question Bank

A sample from our database, grouped by round. Sign up to see the full set.

9 of 16 questions shown

Recruiter Screen

1
Type · motivation
What specifically about 1KOMMA5°'s mission to accelerate the energy transition and our focus on smart energy solutions excites you most as a software engineer?

Coding Screen

2
Type · algorithmic
Given a stream of energy consumption readings (timestamp, kWh) from thousands of smart homes, design an algorithm to efficiently detect anomalies (e.g., sudden spikes or drops) that deviate significantly from the typical consumption pattern for that specific home and time of day. You need to handle a high volume of data.
3
Type · algorithmic
Imagine you have a system that aggregates energy production data from solar panels across many households. Each household reports its production in kWh per minute. Write a function to calculate the total energy produced within a given time range (start_time, end_time) for a specific household, optimizing for performance when querying large datasets.
+ 1 more questions in this round (sign up to unlock)

System Design

4
Type · architecture
Design a scalable system for 1KOMMA5° to manage and optimize energy flow for a network of interconnected smart homes. The system should be able to receive real-time data from smart meters and charging stations, predict demand/supply, and make automated decisions to balance grid load and minimize costs for users. Consider data ingestion, processing, storage, and decision-making components.
5
Type · architecture
How would you design a system to provide personalized energy-saving recommendations to users based on their historical consumption patterns, weather forecasts, and electricity tariff information? Consider the data sources, processing logic, and how recommendations are delivered.
+ 1 more questions in this round (sign up to unlock)

Onsite Coding

6
Type · algorithmic
You are given a list of time intervals, where each interval represents a period a smart home was actively consuming or producing energy (e.g., `[start_time, end_time, type]`, where type is 'consume' or 'produce'). Write a function to calculate the total duration of 'consume' periods that overlap with 'produce' periods for a given day, considering that a home might consume and produce simultaneously (e.g., using solar power while also drawing from the grid).
7
Type · code-quality
Refactor the following Python code snippet, which calculates the average energy price over a month, to improve its readability, maintainability, and efficiency. Pay attention to variable naming, error handling, and potential optimizations for large datasets. Assume `get_daily_prices(date)` returns a list of `(timestamp, price)` tuples for a given day.
+ 1 more questions in this round (sign up to unlock)

Behavioral / Leadership

8
Type · ownership
Tell me about a time you encountered a significant technical challenge in a project related to energy systems or data. How did you take ownership of the problem, what steps did you take to resolve it, and what was the outcome?
9
Type · collaboration
Describe a situation where you had a technical disagreement with a colleague or team member regarding an approach to a feature or system. How did you handle the discussion, and what was the resolution?
+ 4 more questions in this round (sign up to unlock)

Unlock all 16 1KOMMA5° questions, free

No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.

Unlock all 16 1KOMMA5° questions

Interview tracks at 1KOMMA5°

How 1KOMMA5°'s DNA translates across functions. Pick your role.

Compare 1KOMMA5° with similar employers

Same DNA, different bar. Browse the closest companies in our database and see how their loops differ.

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Practice 1KOMMA5° interviews end-to-end

1KOMMA5° Mock Interview

Run a live mock interview with our AI interviewer using 1KOMMA5°-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.

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STAR Stories for 1KOMMA5° Behavioral Rounds

Build a Story Bank of your past wins, mapped to the leadership signals 1KOMMA5° interviewers grade on. Reuse them across every behavioral round.

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1KOMMA5° Interview Prep Hub

The frameworks behind every 1KOMMA5° round: CIRCLES for product sense, hypothesis-driven debugging for analytical, STAR for behavioral. Learn each one in 10 minutes.

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Interview Frameworks

CIRCLES, STAR, AARRR, RICE, MECE. The exact frameworks that make 1KOMMA5° interviewers nod instead of frown. Step-by-step playbooks with the moves and the pitfalls.

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Sample answers

What a strong answer to these 1KOMMA5° interview questions shows.

A strong answer shows: Proposes using data structures like sorted lists or interval trees for efficient range queries.; Discusses potential pre-aggregation strategies for common time windows.; Writes clear, well-tested code..

A strong answer shows: Identifies a specific, relevant new technology or concept.; Describes a structured learning approach (e.g., documentation, tutorials, experimentation, seeking expert advice).; Explains how they applied the learned knowledge to solve a problem or build a feature.; Shows enthusiasm for continuous learning..

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