Fintech app development
Fintech app development differs from ordinary mobile work in the cost of a mistake. You can't "refactor it later": users' money, sensitive data and payment operations mean security and reliability have to live in the architecture from day one, not get bolted on before release.
We build fintech products on React Native + Node.js end to end — banking, payments, expense tracking, wallets and B2B finance apps. One technical lead carries the product through Discovery, MVP and Production and stays on for support after launch. From relevant experience: on BestTrip we handled corporate spend control and policy-based trip approvals; on Devis Group we built online card payments into the product from scratch.
Security as part of the architecture
We build protection into the app, not on top of it. SSL pinning against traffic interception, tokens and keys stored in Keychain (iOS) and Keystore (Android) rather than ordinary storage, encryption of sensitive on-device data. Proper session management: timeouts, re-authentication on critical actions, secure logout and token revocation.
We cover the usual mobile risks: blocking jailbroken/rooted devices where required, screenshot and overlay protection on payment screens, biometrics (Face ID / Touch ID) as an access factor. The level of hardening is chosen for your product and regulator, not set to "maximum by default".
Payments and integrations
We connect payment gateways, acquiring, instant-payment rails, subscriptions and card tokenization. The payment flow is designed to be idempotent: a retried request after a dropped connection won't double-charge, and operation statuses are confirmed via webhooks and server-side checks rather than trusted from the client.
Integrations with banking and financial APIs, KYC providers and anti-fraud services run on the Node.js backend — the mobile app holds no secrets and never touches payment logic directly. What exactly we integrate, and to what depth, is defined during Discovery for your product.
Reliability and testing
In fintech the cost of a bug is measured in money and trust, so testing is not optional. We cover calculation and payment logic with tests, including edge cases (zero amounts, currencies, rounding, partial payments) and behaviour during network failures or backend downtime. Money is handled without rounding errors — never as float.
We set up monitoring and operation logging without leaking sensitive data into logs, plus clear handling and display of payment errors for the user. This is the first thing we look at when auditing someone else's fintech code.
What's included and timelines
Full cycle: Discovery (requirements, threat model, data model and payment flow) → MVP → Production → support. You get iOS and Android apps from a shared React Native codebase, a Node.js backend, architecture and security documentation, and publishing to the App Store and Google Play.
Timelines depend on the feature set, the number of payment and banking integrations and data-protection requirements. A fintech MVP is from 1 month; a precise stage-by-stage estimate follows Discovery. Cost sits within our usual project range and is firmed up against your scope.
FAQ
How much does fintech app development cost?
How do you secure data and payments?
Can you improve or audit an existing fintech app?
Tell us about your product — a path to production follows
A 30-minute call: the task, the risks and the format of working together. No obligations.