Siddhartha Bhatia

I’ve been building software since 2005 — from training engineers, through nearly a decade at a services firm where I grew from web developer to technical architect, to the last eight years engineering large-scale, mission-critical Java systems for global e-invoicing. The kind of systems that move real money and real business documents, where “mostly works” is not an acceptable state.

My deepest specialization is the plumbing of global B2B interoperability: Peppol and EU e-invoicing in production. That means AS4 transport with Oxalis, UBL documents modeled on EN 16931, XSD and Schematron validation pipelines, SMP/SML participant discovery, and RabbitMQ-backed processing that keeps running when a counterparty’s access point does something creative with the spec.

Today I work as a Senior Solution Consultant on e-invoicing compliance across European mandates — invoice lifecycle management, accounts-payable automation, and audit readiness: turning regulatory texts into systems that exchange invoices reliably, at scale, with an evidence trail.

The newest tool in my kit is AI-assisted engineering at the pipeline level: I design spec-driven, multi-agent “factories” — research, build, test, and adversarial verification wired into one gated flow — and have used them to ship dozens of production tools end to end. I bring the same discipline to e-invoicing tooling: the machines draft, the gates verify, and a human who knows the domain signs off.

I also build developer tools for practitioners in this space, and I write here about the architecture that makes machine-to-machine commerce work. I’m based in India and work daily with European e-invoicing ecosystems.