How to Build an App Like Splitwise

Expense entry is the most-used feature and needs to be fast. The minimum flow is: amount, description, who paid, and how to split. Splitting options include equal split among all group members, unequal split by exact amount, split by percentage, and paid-by adjustment for when one person covers more than their share.

For business use cases, expense entry also needs category codes (travel, accommodation, meals, supplies), project or cost center codes for allocation, and a notes field for context. The category and allocation codes are what make the expense data useful for accounting purposes.

Receipt attachment is the difference between an expense record and a verifiable claim. A photo of the receipt attached to the expense provides the documentation needed for reimbursement and audit. On mobile, this is a camera capture; on web, it is a file upload. OCR processing that reads the total from the receipt photo and pre-fills the amount field reduces entry friction significantly.

Groups in Splitwise map to the real-world context: a trip, a household, a project, an event. Each group has its own expense ledger and balance view. Members can be added by phone number, email, or link invitation. For business platforms, groups map to projects, departments, or client engagements.

Group settings control who can add expenses, whether expenses require approval before they become final, and who has visibility into the full ledger versus their own balance only. For businesses, an approval workflow for expenses above a defined threshold is a compliance requirement, not an optional feature.

Member roles matter for business use cases. A project manager who can see all expenses and approve reimbursements has a different permission level from an employee who can only submit their own expenses. Admin, approver, and submitter are the standard roles.

The balance view shows each group member how much they are owed or owe, simplified to the minimum number of transactions needed to settle. This simplification -- called debt simplification or debt consolidation -- is a key feature that reduces the number of payments needed in a group from potentially n*(n-1)/2 to at most n-1.

Balance history shows how the net position between members has changed over time. For business use cases, a project's cumulative spend by category is as important as the individual balance. A project manager seeing total spend against budget at any point in the project lifecycle gets more value from this view than a simple balance.

Currency handling matters for international contexts. A travel group spending in multiple currencies needs each expense recorded in the currency it was incurred, converted to the group's base currency for balance calculation. Exchange rates need to be applied consistently and transparently.

Settlement is the moment when a balance converts to an actual payment. The app should make settlement as easy as possible: a button that pre-fills the amount owed and the payee and triggers a payment through the integrated payment method.

Payment integration options depend on the market. For consumer apps, the integration is with local payment methods: UPI in India, PayNow in Singapore, Venmo or PayPal in the US. For business apps, the integration is with the company's payment infrastructure: bank transfer initiation, corporate card settlement, or accounts payable workflows.

Settlement recording without payment integration (marking an expense as settled manually after paying outside the app) is a fallback that many users need. Not everyone wants to connect a bank account to an expense-splitting app. The manual settlement option keeps the balance ledger accurate even when payment happens outside the platform.

Recurring expenses are a feature that consumer Splitwise handles poorly. A shared household has monthly rent, utilities, and subscriptions that split the same way every month. Entering these manually each month is a friction point that causes users to fall behind on tracking.

Recurring expense rules let a group member configure an expense to repeat at a defined frequency (weekly, monthly, annually) with the same split logic each time. The system generates the expense automatically on the scheduled date. If the amount varies (utility bills change monthly), the auto-generated expense pre-fills the split logic but prompts for the actual amount.

For business platforms, recurring project costs and standing purchase orders are the equivalent. A monthly software license split across three departments does not need to be entered manually each month.

Receipt capture with OCR processing turns a photo of a receipt into a pre-filled expense entry. The OCR reads the total, merchant name, and date. The user confirms the amount and adds the split details. This reduces manual data entry for business users who are capturing receipts throughout the day.

Accounting export is the feature that makes a business expense platform worth paying for. Export formats include CSV for manual import into any accounting system, and direct integrations with QuickBooks, Xero, and Sage using their APIs. The integration sends approved expense entries to the accounting system with the correct category codes, cost center codes, and supporting receipt attachments.

A VAT or GST reclaim report -- listing all expenses with applicable tax, the tax amount, and the receipt reference -- is a specific compliance output that businesses in tax-registered jurisdictions need. This is a feature that Splitwise does not have and that a business-focused platform should.

We build iOS and Android apps and a web application, all connected to the same backend. The mobile apps cover expense entry with receipt photo capture, group management, balance views, and settlement triggers. The web app adds the full admin and reporting views that are better suited to a larger screen.

React Native for mobile and Next.js for web is a cost-effective combination for platforms in this category. We build the camera integration for receipt capture, local currency handling, and push notifications for expense activity in the group.

The splitting engine handles all split types -- equal, by percentage, by exact amount, by shares -- and the debt simplification algorithm that minimizes the number of payments needed to settle a group. This is the mathematical core of the product and needs to be accurate to the cent across all currency and rounding scenarios.

We build the balance engine to handle multi-currency groups, recurring expense automation, and the audit trail that shows how each balance was calculated. The audit trail is a requirement for business use cases where expense records need to support a reimbursement claim or accounting entry.

We build direct integrations with QuickBooks Online, Xero, and Sage using their APIs. Approved expenses sync automatically to the connected accounting system with the correct account codes, cost centers, and receipt attachments. The sync is configurable: some businesses want automatic sync on approval, others want a manual export trigger.

The integration setup in the app lets finance administrators connect their accounting system with OAuth, map expense categories to chart of accounts codes, and configure the sync schedule. Category mapping is important because expense categories in your app need to correspond to the correct accounts in the accounting system.

We integrate an OCR service (Google Vision, AWS Textract, or similar) to extract total, merchant, and date from receipt photos. Extracted data pre-fills the expense entry form. The original receipt image is stored against the expense record for the life of the record.

Document management covers storage, retrieval, and access control for receipts. Business users need to be able to pull all receipts for a specific period for VAT reclaim or audit purposes. The export includes the receipt images alongside the expense data.