Best of Fintech — October 2025

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    Article
    Avatar of allthingsdistributedAll Things Distributed·30w

    What is USSD (and who cares)?

    USSD, a 30-year-old messaging protocol requiring only 2G connectivity, powers hundreds of billions in financial transactions across Sub-Saharan Africa through companies like M-Pesa and Moniepoint. Behind simple menu-driven interfaces on feature phones, these platforms run sophisticated cloud architectures with ML-powered fraud detection and IoT systems. The technology demonstrates how builders solve real customer problems by choosing suitable tools over shiny ones, creating profitable businesses while serving communities with limited internet access and smartphone penetration.

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    Article
    Avatar of growwenggGroww Engineering·33w

    Building 915: Inside Groww’s High-Performance Trading Terminal

    Groww Engineering built 915.Trade, a high-performance web-based trading terminal for professional traders. The platform features a modular architecture with real-time data streaming using binary messaging, Zustand for optimized state management, and React Compiler for automatic optimization. Key features include direct chart trading, dynamic option chains with live Greeks, a unique straddle chart for volatility tracking, and a scalper widget with keyboard shortcuts. The system uses an EventBus with BroadcastChannel API for widget linking across tabs, enabling traders to create synchronized, shareable workspace layouts.

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    Article
    Avatar of medium_jsMedium·30w

    Create a Stock Screener with MCP Servers in Minutes

    Learn how to build a stock screener using Financial Modeling Prep's MCP Server and the Model Context Protocol. The tutorial demonstrates fetching structured financial data through a unified interface, filtering stocks based on metrics like P/E ratio and debt-to-equity, and implementing the screener in Python with pandas. Setup involves either using Cursor IDE or running a local Docker container, with the MCP server providing clean JSON responses without managing multiple API endpoints or authentication.

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    Article
    Avatar of hnHacker News·30w

    Why We’re Never Using Wise Again – A Cautionary Tale from a Business Burned – Shaun’s Data Diaries

    A business shares their experience with Wise (formerly TransferWise) after their accounts were permanently restricted following a routine address update. Despite providing legally compliant documentation, the company faced rejection based on document naming conventions, received contradictory support responses, and ultimately had both business and personal accounts closed without clear explanation or meaningful appeal process. The situation escalated to funds being held in limbo and requiring external dispute resolution. The author warns businesses against relying solely on Wise for financial operations due to lack of transparency and customer support escalation paths.

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    Article
    Avatar of lobstersLobsters·33w

    Why we didn't rewrite our feed handler in Rust

    Databento chose C++ over Rust for rewriting their market data feed handler despite using Rust successfully elsewhere. The decision centered on three key friction points with Rust's ownership model: buffer reuse patterns conflicting with lifetime tracking, self-referential structs requiring workarounds, and less mature compile-time generics compared to C++ templates. While Rust offers superior safety guarantees and tooling, C++ provided more control over memory layout, better code reuse from existing systems, and greater team expertise for this specific low-latency, high-throughput use case processing 14 million messages per second.

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