High-Performance Fintech Architecture: Scaling to 10k Req/Sec

In the modern financial landscape, the “Integration Gap” is a silent killer of innovation. Enterprise applications often struggle to balance the stability of legacy banking with the agility of decentralized finance (DeFi). Attempting to bridge these worlds usually results in massive technical debt or “Super-App bloat”—sluggish interfaces that lose user trust.

At Acme Software, we engineered Wallet, a white-label fintech solution designed to solve these exact challenges. Here is how we built a system capable of processing 10,000 requests per second with zero downtime.

The Integration Gap: Why Legacy Fintech Architectures Fail

Most neobanks fail to scale because they are built on monolithic architectures that are tightly coupled. When you try to orchestrate services like Identity (Auth0), KYC (Sumsub), and Banking (Unit) into one flow, the system becomes fragile.

Key Challenges we identified:

Legacy Monoliths: Inability to scale specific components independently.
App Bloatware: Heavy mobile clients that lead to dropped frames and poor UX.
State Consistency: The difficulty of managing internal ledgers against external, asynchronous blockchain rails.

Engineering for Scale: The “Wallet” Tech Stack

To achieve enterprise-grade performance, we moved away from standard Node.js/Python setups in favor of a high-concurrency, modular ecosystem.

High-Performance Orchestration with Golang

We selected Golang for the backend orchestration layer. By utilizing Go’s goroutines and channels, Wallet can handle parallel API calls—such as fetching fiat and crypto balances simultaneously—without memory exhaustion.

Speed: Using the Gin framework, we achieved O(1) route lookup complexity.
Safety: We implemented a strict Idempotency Key mechanism (backed by Redis) to prevent duplicate transactions during network flickers.

Native-Tier Mobile Experience via Flutter & Impeller

For the frontend, we leveraged Flutter to maintain a single codebase without sacrificing performance. By adopting the Impeller rendering engine, we eliminated runtime “jank” (stutter).

60 FPS Performance: Precompiled shaders ensure the UI stays buttery smooth, even during complex financial charting.
White-Label Ready: Our unique build pipeline allows for rapid branding injection, moving from “dev” to “deployment” in weeks rather than months.

Solving Data Integrity with Distributed Transactions

In fintech, money can never be “lost” in the ether. We leveraged MongoDB’s multi-document transactions to ensure ACID compliance. To bridge the gap between fiat and crypto, we used the Saga Pattern. This orchestration-based state machine manages complex workflows and automatically executes “Compensating Transactions” (refunds) if any step in the multi-chain process fails.

Key Results: Performance by the Numbers

The transition to an event-driven, modular architecture yielded industry-leading results:

10,000 Concurrent Requests/Sec: Seamlessly handled viral growth spikes.
<16ms UI Render Time: Consistent high-performance experience for high-net-worth users.
Rapid Time-to-Market: Branded MVPs delivered in weeks, not months.

Conclusion: Building the Future of Borderless Liquidity

Building a high-performance fintech app requires more than just a good UI; it requires a foundation that prioritizes data integrity and massive scalability. Whether you are launching a neobank or a DeFi wallet, your architecture is your greatest competitive advantage.