# Lonmerco Software

Lonmerco Software, trading as London Merchants & Co Ltd, is a Winchester-based software developer specialising in bespoke accounting solutions for professional service firms. The company designs and delivers desktop-based software systems specifically tailored to the needs of accountants, auditors, and consulting practices.

The business primarily serves fee-based professional firms that require robust time tracking and billing infrastructure. Their flagship product, Tandem (Time & Expense Management), addresses a critical operational need by providing comprehensive control over time recording, expense tracking, invoicing, collections and business performance evaluation. This is complemented by eadder, a specialised business calculator and adding machine application that functions as a modern alternative to traditional till rolls, offering enhanced functionality including tax calculations, cost-margin-sell computations, and premium/discount calculations.

What distinguishes Lonmerco Software from competitors is their steadfast commitment to data security and independence. All software operates on Windows platforms and resides entirely on clients' own office networks and servers—there is no reliance on cloud-based infrastructure. This approach appeals to firms concerned about data sovereignty and those preferring to maintain complete control over sensitive client information and accounting records.

The company offers perpetual licensing with one-time payments rather than recurring subscription models, providing transparency and cost predictability for professional practices. This pricing structure, combined with locally-hosted solutions and purpose-built functionality for accountants and auditors, positions Lonmerco Software as a pragmatic alternative to cloud-dependent competitors.