Software Development

An ERP or CRM built on a generic platform forces the business to adapt its operations to the software's assumptions — approval workflows that do not match the actual authority structure, reporting modules that aggregate the wrong dimensions, and integration points that require expensive middleware to connect to the systems the business already uses. NullStack builds ERP and CRM systems from the process up: we map every departmental workflow, data input point, approval chain, and reporting requirement in a structured discovery phase before the first line of code is written. The resulting system reflects the business exactly as it operates, with module architecture that allows individual departments to be extended or reconfigured without touching the rest of the system. Performance benchmarking is built into the acceptance criteria — query response times, concurrent user load handling, and data export speed are verified in staging before deployment.

Building a SaaS product requires a different architectural decision set than building an internal enterprise tool. Multi-tenancy — the ability to serve multiple client organisations from a single application instance while maintaining strict data isolation — must be designed into the data model from day one, not retrofitted after the product reaches scale. NullStack's SaaS architecture uses schema-level tenant isolation in PostgreSQL, giving each client organisation a logically separate data environment while sharing compute resources efficiently. Subscription and billing management is implemented via Stripe's API, with webhook-driven entitlement management that adjusts feature access in real time based on subscription state. The deployment pipeline uses Docker and a CI/CD configuration that allows zero-downtime releases — critical for a product where scheduled maintenance windows erode customer trust.

Legacy system modernisation is the highest-risk category of software project because the failure mode — disrupting a live operational system — has direct revenue consequences. NullStack approaches legacy migration using a strangler fig pattern: new modules are built in the modern architecture and connected to the legacy system via an API bridge, allowing the old system to be progressively retired rather than replaced in a single cutover event. This approach means the business operates on the legacy system in full until each module has been individually validated in production — reducing the blast radius of any individual issue to a contained module rather than the entire system. We begin every modernisation engagement with a full codebase and database audit, producing a dependency map that identifies which components can be migrated independently and which have cross-module entanglements that require sequenced migration.

Modern enterprise operations run on a portfolio of specialised tools: an ERP for operations, a CRM for sales, a WMS for logistics, an accounting platform for finance. The integration layer between these systems is frequently the most fragile part of the stack — built on ad hoc scripts, manual data exports, or brittle point-to-point connections that break whenever one system is updated. NullStack builds integration layers as first-class software: RESTful APIs with versioning, authentication, rate limiting, and comprehensive error logging, deployed as independent microservices that can be updated or replaced without touching the systems they connect. For clients requiring real-time data synchronisation across systems, we implement event-driven architectures using message queues (RabbitMQ or Redis Streams) that decouple the producing system from the consuming system and handle failure states gracefully.