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What we do

Custom Software

Purpose-built systems for problems off-the-shelf software cannot reach, engineered for scale, audit and handover.

Custom Software at a glance

// PRACTICE 04

Custom Software

Active Practice
What it is
Purpose-built systems for problems off-the-shelf software cannot reach, engineered for scale, audit and handover.
Platforms
Your cloud, your identity provider, your compliance boundary.
You get
Source, infrastructure as code, an SBOM per release, and a runbook written for someone who has never met us.
Typical first step
A discovery engagement that ends in an architecture decision record you own.
Dedicated engineering squadExplore Custom Software

The boundary, stated up front.

Lock-in. Everything we build is deployable by your own team, and the handover terms are in the contract from day one.

The environments this practice is built for.

What each environment does to a system that was not designed for it.

Banking & Financial ServicesMoney moves with a reviewable record behind it, or it does not move. Audit is a feature, not paperwork.Insurance & RiskRules differ by policy, region and date. The logic has to still be readable a year from now.Regulated & Public ServicesAccess, retention and approval are the design, not a layer added at the end.

Reference designs, not case studies.

How we would approach three problems that come up often. No client’s numbers appear here, because none of these is a client’s system.

Double-entry · distributed SQL · multi-region

A double-entry ledger with reconciliation built in

Every entry has to balance before it is written, and the ledger is reconciled against outside statements continuously, so drift shows up before settlement rather than at month end.

Four stagesStage 01 of 04 Processing
ACTIVE
Node 01

Transaction intake

API and file feeds
Mutual TLS

Receives transactions and statements from the systems that originate them.

Node 02

Ordering

Sequenced, idempotent
Consensus-backed

Gives every entry one position in one order, so a retry can never post twice.

Node 03

Ledger core

Double-entry rules
Transactional

Refuses any entry whose debits and credits do not balance.

Node 04

Storage

Distributed SQL database
Serializable isolation

Keeps the ledger consistent across regions and survives the loss of one.

When something fails
An entry that does not balance is rolled back and logged, never posted.
Cross-currency balances are checked for rounding drift before settlement.
Running in more than one region means losing a data centre does not lose data.

What your security review will ask about here.

OWASP ASVS 5.0Level 2 verification on every release
SLSA v1.0Build Level 2 provenance on release artifacts
CycloneDX SBOMIssued with every build
Read the control register

The first three gates, and what each one leaves you with.

01DiscoveryA written problem statement, in your words, that you own.
02Process mappingCurrent-state map with the manual steps costed in hours and money.
03System designArchitecture decision record, integration inventory, and a fixed scope with a price.
Start a Custom Software projectAll seven gates