Payment messaging, software engineering and practical AI.
I’m Dave Garry, a CTO and former software-company founder with around 25 years of software engineering experience. I write practical guides, build tools and explore how AI agents can help engineers understand, test and debug payment systems.
For developers and technical teams working with ISO 20022, payment integrations and engineering automation.
Start Here
Recommended foundational guides on payment messaging flows and AI engineering.
Understand a direct debit message
Explore the pacs.003 message, its role in a direct debit flow and its key XML fields.
Understand payment recalls
Learn how camt.056 cancellation requests relate to investigation responses and returned funds.
Explore AI for payment engineering
Read about using AI to explain ISO 20022 validation errors and the importance of grounding explanations in rules.
Core Systems Toolkit
Interactive developer utilities for formatting, syntax-checking, and diffing messaging payloads.
More payment guides
Deep dives into clearing, settlement, PACS, PAIN, and CAMT messaging standards.
What is SEPA?
SEPA simplifies Euro transfers across 41 countries. Learn about SCT, SDD, and how this single market for payments reduces costs and promotes integration.
Ripple and ISO 20022
Ripple is leveraging blockchain and ISO 20022 to revolutionize cross-border payments. Explore its adoption of the global standard and the role of XRP Ledger.
What is Cross-border Payments and Reporting Plus (CBPR+)
CBPR+ defines the SWIFT network's transition to ISO 20022 for cross-border payments. Understand the rollout timeline and how MT messages map to the MX format.
Working on payment messaging or AI agents?
I’m interested in the practical problems engineers encounter when building, testing and debugging payment systems. Connect with me to compare approaches, share feedback or discuss ideas.