🚀 My UiPath Frontend Engineer Interview Experience (2025) | Software Engineer II

📍 Location: Remote / Bengaluru
🧠 Role: Software Engineer II 
💰 Compensation: ₹35 LPA Fixed + $150-200K ESOPs [vested in 4 years]

🏢 About UiPath

UiPath is a global leader in Robotic Process Automation (RPA), helping enterprises automate repetitive tasks and streamline workflows. With a strong presence across the US, Europe, and India, UiPath blends AI, ML, and automation tools to deliver intelligent software robots that improve business efficiency.

For frontend engineers, UiPath offers opportunities to work on complex enterprise-grade dashboards, automation interfaces, and real-time data-driven UI systems, making it an exciting choice for engineers passionate about performance, accessibility, and large-scale design.

🔥 Round 1: Data Structures & Algorithms

This round tested algorithmic thinking, problem-solving, and JavaScript fundamentals via 2 key problems.

✅ Problem 1: Maximum Robbery Amount

A thief wants to rob houses along a street. He cannot rob two adjacent houses. Return the maximum amount he can rob.

📌 Approach:
We calculate the sum at even and odd indexes, then return the max.

💡 Solution:

/**
 * 🧠 Optimal DP solution for House Robber Problem
 * The thief cannot rob adjacent houses.
 * We keep track of two states:
 * - prevMax: Max loot up to previous house
 * - currMax: Max loot up to current house
 */

function getMaximumRobberyAmount(houses = []) {
    let prevMax = 0; // 💰 Max loot up to house i-2
    let currMax = 0; // 💰 Max loot up to house i-1

    for (let amount of houses) {
        let temp = currMax;
        // 🧮 Either rob current house + prevMax, or skip and take currMax
        currMax = Math.max(prevMax + amount, currMax);
        prevMax = temp;
    }

    return currMax; // 🥇 Final maximum amount
}

// ✅ Test Cases
console.log(getMaximumRobberyAmount([1, 2, 3, 1]));      // Output: 4
console.log(getMaximumRobberyAmount([2, 7, 9, 3, 1]));   // Output: 12
console.log(getMaximumRobberyAmount([2, 1, 1, 2]));      // Output: 4

🧠 Explanation:

• At each house, you decide:
  • Rob it ➡️ add its value to prevMax
  • Or skip it ➡️ take currMax (value up to the previous house)
• Then update the values and move on.

🔥 Time & Space Complexity:

• Time: O(n) ✅
• Space: O(1) ✅ (no extra array used, just two variables)

✅ Problem 2: Reverse Words in a String

Given a sentence, reverse every word but maintain the word order.

💡 Solution:

/**
 * 🔄 Function to reverse each word in a sentence
 * 💬 Input: A sentence with words separated by spaces
 * 🎯 Goal: Reverse the characters of each word individually
 * 🔧 Steps:
 *  1️⃣ Split the sentence into words using ' '
 *  2️⃣ For each word, split into characters, reverse, and join back
 *  3️⃣ Join all reversed words with a space to form final sentence
 */

function reverseWords(sentence) {
    return sentence
        .split(' ') // 🧱 Step 1: Split sentence into words
        .map(word => word.split('').reverse().join('')) // 🔄 Step 2: Reverse each word
        .join(' '); // 🔗 Step 3: Join the reversed words
}

// 🧪 Test Case
console.log(reverseWords("Welcome to UiPath")); 
// ✅ Output: "emocleW ot htaPiU"

✅ Output:

"emocleW ot htaPiU"

📌 What they were checking:

• Familiarity with map, split, join
• Clean, readable code
• Handling edge cases (like extra spaces or punctuation)

⚙️ Round 2: Machine Coding Challenge

This was a hands-on practical task to assess the ability to build features in plain JavaScript without libraries.

✏️ Problem: Build a Notes App

Requirements:

• Add/Edit/Delete notes
• Store them in memory
• Use pure Vanilla JS (No React, jQuery, etc.)

📌 Evaluation Criteria:

• Modularity of JS functions
• DOM manipulation efficiency
• Code readability and event handling

❓ Additional Questions Asked:

• ✅ Why is JavaScript faster than some other languages in the browser?
• ✅ What is Hoisting in JS? Explain with examples.
• ✅ Explain the Event Loop and how JavaScript is single-threaded yet async.

🎯 Key Takeaway:
They expected a structured UI, thoughtful event delegation, and good naming conventions — all without external tools.

🛠️ Round 3: Low-Level Design (LLD)

Despite the label, this round was more data-structure focused than actual component/system design.

✅ Problem: Frequency of Numbers

Given a 2D array, return the frequency of each number.

💡 Solution:

// 🧪 Sample input: Array of arrays containing numbers
let SAMPLE_DATA = [
  [1, 2, 3, 2],
  [2, 5, 1, 7, 1],
  [3, 4, 2, 5, 2, 8]
];

/**
 * 📊 Function to count frequency of each number in a nested array
 * @param {Array} inputData - Nested array of numbers
 * @returns {Object} frequency - Object with number as key and its frequency as value
 */
function getNumberFrequency(inputData = []) {
    let frequency = {}; // 📦 Object to store frequency
    let flatList = inputData.flat(); // 🧯 Flatten the 2D array into a 1D array

    flatList.forEach(num => {
        // 🔁 Increment count if exists, else initialize to 1
        frequency[num] = (frequency[num] || 0) + 1;
    });

    return frequency; // 📬 Return the frequency object
}

// 🧾 Output: Frequency of each number
console.log(getNumberFrequency(SAMPLE_DATA));
// ✅ Output: { '1': 3, '2': 4, '3': 2, '4': 1, '5': 2, '7': 1, '8': 1 }

✅ Final Output:

{ '1': 3, '2': 4, '3': 2, '4': 1, '5': 2, '7': 1, '8': 1 }

🧠 Follow-Up Discussions:

• How would you design a Chat App UI (event-based updates, state)?
• Explain the Pub-Sub model and how it helps with real-time systems.

📌 Observation:
Instead of frontend-focused design topics (like reusable components, dynamic layouts, or performance patterns), this round leaned heavily on algorithmic problem-solving.

❌ What Went Wrong (My Honest Reflection)

While I cleared the technicals with confidence, I feel the LLD round missed the core aspect of what frontend engineers bring — UX architecture, design systems, state management, etc.

📉 Instead of testing:

• Component-driven development
• State libraries (Redux, Zustand)
• UI scaling strategy (responsive layouts, accessibility, SSR)

…it felt like a DSA-heavy backend screening.

💡 Key Takeaways

• Be crystal clear on Vanilla JS, especially:
  • map, reduce, filter, closures, hoisting
• Practice DSA problems that involve arrays, strings, and recursion
• Brush up on browser internals (Event Loop, DOM diffing, reflow)
• Know how to build common UI widgets from scratch

📌 Compensation Details

🚀 Final Thoughts

Though I didn’t receive an offer, the process helped me:

• ✅ Reinforce my JS core concepts
• ✅ Spot gaps in my frontend architecture answers
• ✅ Understand the importance of LLD for the frontend, especially in enterprise companies

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💡 Tips to Crack the UiPath Frontend Interview

1. ✅ Master JavaScript Fundamentals
   • Focus on Closures, Hoisting, Event Loop, Promises, and this keyword.
   • Be ready to write polyfills (e.g., Promise.all, Array.prototype.map, getElementByStyles).
2. 💻 Strong DSA Practice
   • Focus on arrays, objects, recursion, and dynamic programming (like the Maximum Robbery Problem).
   • Platforms: LeetCode, CodeSignal, HackerRank.
3. 🛠 Be Hands-on with Machine Coding
   • Practice building apps in Vanilla JS (e.g., Notes App, Todo, Progress Bars).
   • Learn to code with a readable structure and reusability.
4. ⚙️ Understand System Design & LLD
   • Practice designing real-world apps like Chat App, Notes Manager.
   • Learn the basics of Pub-Sub, state management, and modular components.
5. 🎯 Communicate Clearly
   • Explain your thought process during problem-solving and design rounds.
   • Break down the problem and use diagrams if allowed.
6. 📖 Project Readiness
   • Prepare to discuss your past projects—architecture, challenges, performance improvements, etc.
7. 💬 Behavioral Rounds Matter
   • Be honest, clear, and confident in your answers during the HM round.

📚 Recommended Topics to Prepare

🔹 JavaScript:

• Hoisting, Closures, Event Loop
• Callbacks vs Promises vs async/await
• Polyfills & custom implementations
• Debounce, Throttle, Memoization
• ES6+: Spread, Rest, Destructuring

🔹 HTML/CSS:

• Flexbox & Grid
• Responsive design
• BEM naming, Accessibility
• CSS Performance tricks (repaint vs reflow)

🔹 React (or UI Framework of choice):

• Lifecycle, Hooks (useMemo, useCallback, useRef)
• Conditional rendering, List rendering
• Portals, HOC, SSR vs CSR
• Lazy loading, Context API

🔹 System Design:

• Component Design
• Data flow architecture
• Infinite Scroll, Debounced Search, Chat UI
• Pub-Sub Model, Optimized Rendering

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