The latest articles on DEV Community by Samarth Nagpal (@samarth_nagpal_7c1ba5f72b). https://dev.to/samarth_nagpal_7c1ba5f72b https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3726525%2F5c0aa1e1-7045-4ac2-a9f1-385749519747.png https://dev.to/samarth_nagpal_7c1ba5f72b en Samarth Nagpal Thu, 22 Jan 2026 15:58:10 +0000 https://dev.to/samarth_nagpal_7c1ba5f72b/i-built-splitease-an-unlimited-expense-splitting-app-without-paywalls-splitwise-alternative-43a9 https://dev.to/samarth_nagpal_7c1ba5f72b/i-built-splitease-an-unlimited-expense-splitting-app-without-paywalls-splitwise-alternative-43a9 <h2> The Problem </h2> <p>During a weekend trip with roommates, we hit Splitwise's <strong>3 expenses per day limit by noon</strong>.</p> <p>Breakfast, gas station stop, and hotel check-in used up our quota. We had to either <strong>wait until midnight</strong> to log lunch and dinner or <strong>pay for premium just to track our own spending</strong>.</p> <p>That felt ridiculous for such a basic feature — so <strong>SplitEase</strong> was built to solve exactly this problem.</p> <h2> What is SplitEase? </h2> <p><strong>SplitEase</strong> is a completely free, no-limits expense splitting app for students, flatmates, and travel groups.</p> <p>Think <strong>Splitwise — but without artificial restrictions.</strong></p> <p>Live App: <a href="https://www.split-ease.app/" rel="noopener noreferrer">https://www.split-ease.app/</a><br> Product Hunt: <a href="https://producthunt.com/posts/splitease-2" rel="noopener noreferrer">https://producthunt.com/posts/splitease-2</a></p> <h2> Key Features </h2> <ul> <li>Unlimited expenses per day — no artificial restrictions</li> <li>Unlimited groups — track as many friend circles as needed</li> <li>Real-time sync across all devices using WebSockets</li> <li>Push notifications for payment reminders</li> <li>Smart debt simplification algorithm</li> <li>Edit and delete expenses anytime — included free</li> <li>PWA support with offline capabilities</li> <li>Clean, modern interface</li> <li>Completely free forever — no ads, no premium tier</li> </ul> <h2> Tech Stack </h2> <h3> Frontend </h3> <ul> <li>React with Zustand for state management</li> <li>React Router for navigation</li> <li>Framer Motion for animations</li> <li>Socket.io-client for real-time updates</li> <li>PWA with service workers and push notifications</li> </ul> <h3> Backend </h3> <ul> <li>Node.js + Express.js RESTful API</li> <li>MongoDB with Mongoose ODM</li> <li>Socket.io for WebSocket connections</li> <li>JWT authentication</li> <li>Google OAuth 2.0 integration</li> <li>Brevo for email notifications</li> </ul> <h3> Deployment </h3> <ul> <li>Frontend: Vercel</li> <li>Backend: Railway</li> <li>Database: MongoDB Atlas</li> </ul> <h2> Technical Challenges and Solutions </h2> <h3> 1. Real-time Debt Updates Across Multiple Devices </h3> <p>When one person adds an expense, <strong>everyone in the group must instantly see updated balances</strong> — without refreshing the page.</p> <p>This became tricky because:</p> <h4> What Was Going Wrong </h4> <ul> <li>Multiple users could edit or add expenses at the same time</li> <li>Traditional REST polling caused delays and unnecessary server load</li> <li>Sending updates to all connected users wasted bandwidth</li> <li>Race conditions caused outdated balances to briefly appear</li> </ul> <h4> How It Was Fixed </h4> <h5> Group-based WebSocket Rooms </h5> <p>Each group has its own dedicated Socket.io room.</p> <p>Only members of that group receive updates — keeping traffic efficient and isolated.<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight javascript"><code><span class="c1">// Server-side</span> <span class="nx">socket</span><span class="p">.</span><span class="nf">join</span><span class="p">(</span><span class="s2">`group-</span><span class="p">${</span><span class="nx">groupId</span><span class="p">}</span><span class="s2">`</span><span class="p">);</span> <span class="nx">io</span><span class="p">.</span><span class="nf">to</span><span class="p">(</span><span class="s2">`group-</span><span class="p">${</span><span class="nx">groupId</span><span class="p">}</span><span class="s2">`</span><span class="p">).</span><span class="nf">emit</span><span class="p">(</span><span class="dl">'</span><span class="s1">expense-added</span><span class="dl">'</span><span class="p">,</span> <span class="nx">newExpense</span><span class="p">);</span> </code></pre> </div> <h5> Event-Driven State Updates </h5> <p>Instead of refetching all expenses:</p> <ul> <li> <p>Clients listen for events like:</p> <ul> <li>expense-added</li> <li>expense-updated</li> <li>expense-deleted</li> </ul> </li> <li><p>Zustand store updates only affected data</p></li> <li><p>UI re-renders instantly</p></li> </ul> <h5> Optimistic UI With Rollback </h5> <p>To keep the app feeling fast:</p> <ul> <li>UI updates immediately when a user adds an expense</li> <li>Backend confirmation follows</li> <li>If a request fails, the UI automatically rolls back</li> </ul> <h5> Connection Recovery Handling </h5> <p>Socket reconnection was added to handle:</p> <ul> <li>App backgrounding</li> <li>Network drops</li> <li>Device sleep</li> </ul> <p>On reconnect:</p> <ul> <li>Client re-joins all group rooms</li> <li>Syncs latest balances</li> <li>Prevents stale state bugs</li> </ul> <h4> Result </h4> <ul> <li>Sub-second balance updates</li> <li>No page refresh required</li> <li>Works smoothly across multiple devices</li> <li>Reduced server load compared to polling</li> </ul> <h3> 2. Debt Simplification Without Weird Rounding Bugs </h3> <p>The first version of the “who owes whom” logic worked on floats.</p> <p>That caused results like:</p> <ul> <li>₹249.999999</li> <li>Off-by-₹1 mismatches</li> <li>Totals not summing to zero</li> </ul> <h4> What Was Going Wrong </h4> <ul> <li>Floating-point math caused precision errors</li> <li>Errors accumulated across many expenses</li> <li>Final debt graph didn’t balance mathematically</li> </ul> <h4> How It Was Fixed </h4> <h5> Store Money as Integers </h5> <p>All values are stored in <strong>paise instead of rupees</strong>.</p> <p>Example:</p> <ul> <li>₹250.50 → stored as <code>25050</code> </li> </ul> <h5> Integer-Only Simplification Algorithm </h5> <p>The entire simplification logic runs on integers.</p> <p>Conversion back to rupees happens only at display time.</p> <h5> Added Sanity Checks </h5> <p>Automated tests verify:</p> <ul> <li>Sum of balances always equals zero</li> <li>No fractional remainders</li> <li>No negative rounding artifacts</li> </ul> <h4> Result </h4> <ul> <li>Perfectly balanced settlements</li> <li>No decimal glitches</li> <li>Accurate large-group calculations</li> </ul> <h3> 3. Web Push Notifications That Actually Deliver </h3> <p>Web push notifications were far harder than just installing a library.</p> <h4> What Was Going Wrong </h4> <ul> <li>Users granted permission but never received notifications</li> <li>Invalid subscriptions accumulated</li> <li>Old service workers remained active</li> <li>Silent failures</li> </ul> <h4> How It Was Fixed </h4> <h5> Subscription Validation Endpoint </h5> <p>Each subscription is:</p> <ul> <li>Verified before saving</li> <li>Validated for required fields</li> <li>Rejected if malformed</li> </ul> <h5> Automatic Cleanup </h5> <p>When push sending fails:</p> <ul> <li>Subscription is deleted automatically</li> <li>Prevents repeated failures</li> <li>Keeps database clean</li> </ul> <h5> Versioned Service Worker Strategy </h5> <p>Service workers are versioned.</p> <p>When a new version is detected:</p> <ul> <li>Old worker is invalidated</li> <li>Client re-registers</li> <li>Everyone converges to latest logic</li> </ul> <h4> Result </h4> <ul> <li>Reliable cross-browser delivery</li> <li>Consistent mobile notifications</li> <li>Clean subscription database</li> </ul> <h2> Architecture Highlights </h2> <ul> <li>Modular API structure (routes, controllers, services)</li> <li>JWT authentication middleware</li> <li>Centralized error handling</li> <li>MongoDB indexing on <code>userId</code> and <code>groupId</code> </li> <li>Input validation using express-validator</li> <li>Secure CORS configuration</li> </ul> <h2> What's Next? </h2> <p>Based on Product Hunt feedback:</p> <ul> <li>Multi-currency support</li> <li>Trip-based expense summaries</li> <li>Export to PDF and Excel</li> <li>WhatsApp and SMS notifications</li> <li>Expense categories and analytics</li> </ul> <h2> Try It Out </h2> <p>SplitEase is built for:</p> <ul> <li>Students</li> <li>Flatmates</li> <li>Travel groups</li> </ul> <p>No limits. No paywalls. No ads.</p> <p>Live App: <a href="https://www.split-ease.app/" rel="noopener noreferrer">https://www.split-ease.app/</a></p> <h2> Lessons Learned </h2> <ul> <li>Real-time sync requires careful race-condition handling</li> <li>OAuth and email auth need heavy testing</li> <li>PWAs require proper service worker lifecycle management</li> <li>User feedback directly shapes roadmap</li> </ul> <p>Built with React, Node.js, MongoDB, and many late nights.</p> <p>Launching on Product Hunt today — would love your feedback.</p> webdev javascript react startup