Case Study
Stirling PDF

How Nexus Cloud Reduced Invoice Processing Time by 74%
Client: Nexus Cloud Ltd Industry: Financial Technology (FinTech) Date: February 2026
Client Overview
Nexus Cloud Ltd is a London-based financial technology company providing accounts-payable automation software to mid-market businesses across the UK and Ireland. Founded in 2017, the company employs 210 staff and processes over 4 million invoices annually on behalf of its 320 enterprise clients. Following a Series B funding round in 2024, Nexus Cloud entered a rapid growth phase, scaling its customer base by 45% in eighteen months.
Challenge
Rapid customer growth exposed significant bottlenecks in Nexus Cloud's internal document management and PDF generation infrastructure. The legacy system — a patchwork of third-party libraries and manual export workflows — was unable to scale with demand. Key problems included: - Invoice and statement generation times averaging 8.2 seconds per document, causing SLA breaches during peak periods - No support for branded, client-configurable document templates, resulting in high-value customers receiving generic output - A manual quality-assurance step requiring three finance staff to review approximately 600 documents per day - An inability to generate documents programmatically via API, blocking integrations with downstream ERP systems The backlog had grown to 12,000 unprocessed documents at peak, and customer satisfaction scores related to document delivery had fallen to 61%.
Solution
Nexus Cloud partnered with Stirling PDF to deploy a fully integrated document generation and processing pipeline. The solution centred on Stirling PDF's AI document creation capabilities, enabling Nexus Cloud to: - Define and version-control a library of 24 branded document templates covering invoices, statements, remittance advice, and credit notes - Generate PDF documents programmatically via a REST API with average end-to-end latency of 2.1 seconds - Apply client-specific theming — including custom fonts, colour schemes, and logos — at the point of generation without manual intervention - Route completed documents directly to Nexus Cloud's distribution service via webhook, eliminating the manual QA step for standard document types
Implementation
The implementation was completed in three phases over eight weeks: Phase 1 (Weeks 1–3): Template Migration. Nexus Cloud's design team worked with Stirling PDF's onboarding engineers to convert the 24 legacy document designs into Stirling PDF's HTML-based template format. All templates were validated against a sample of 500 historical documents. Phase 2 (Weeks 4–6): API Integration. Nexus Cloud's engineering team integrated the Stirling PDF generation API into their existing invoice processing microservice. A staging environment with synthetic load testing at 200 concurrent requests confirmed that latency remained below 2.5 seconds at the 95th percentile. Phase 3 (Weeks 7–8): Parallel Running and Cutover. Both systems ran in parallel for two weeks. A total of 38,000 documents were validated side-by-side. No material discrepancies were identified. The legacy system was decommissioned on 14 October 2025.
Results
Within 90 days of full deployment, Nexus Cloud reported the following outcomes: - Document generation time reduced from 8.2 seconds to 2.1 seconds — a 74% improvement - Manual QA headcount reallocated from document review to higher-value tasks; estimated annual saving of £87,000 in operational cost - Zero SLA breaches in November and December 2025 (versus 14 in the same period the prior year) - Customer satisfaction score for document delivery increased from 61% to 89% - 12 enterprise clients activated custom-branded templates within the first 60 days, generating an estimated £34,000 in incremental upsell revenue for Nexus Cloud - The document backlog was eliminated within the first week of operation
Client Testimonial
"Switching to Stirling PDF was one of the smoothest technology transitions we have made. The onboarding team understood our constraints from day one, and the API integration took our engineers less than a week. The impact on our document throughput and customer feedback has been immediate and measurable. We are already planning to extend the platform to cover our client-facing reporting suite in Q2 2026."
— Marcus Webb, VP of Engineering, Nexus Cloud Ltd
Conclusion
Nexus Cloud's experience demonstrates how organisations experiencing rapid growth can use Stirling PDF to eliminate document processing bottlenecks without sacrificing quality or brand consistency. By replacing a fragile legacy stack with a scalable, API-first generation platform, Nexus Cloud recovered significant operational capacity, improved customer satisfaction, and created new commercial opportunities through branded document customisation. The project delivered full return on investment within eleven weeks of go-live.