FINOPS CONSULTING
CASE STUDY
Two clouds. One question: who should be charged?
A production cost platform for a dual-cloud Azure estate: commercial and government tenants, dozens of subscriptions, and AI spend nobody could see. Built to answer what is being spent, by whom, and who should be charged for it, and live in front of leadership within days of the first working day.
Cloud spend had climbed roughly 75% in five months and nobody could say precisely why. The estate spanned two Azure tenants that behaved differently and were being discussed as one number. Tagging had collapsed into folklore: ten allocation concepts spelled twenty-five different ways, which meant finance had cost centers and project codes on paper and no defensible way to charge anything back. And a fast-growing slice of the bill, AI coding assistants, was invisible: buried inside the cloud invoice and double-counted in one briefing before this platform existed to say otherwise.
The platform reads the cloud's own cost APIs directly: no export pipelines, no data factory, nothing to babysit. Every row carries both billed and effective cost side by side, FOCUS-style, so a forgotten filter can't silently double a total. Resource tags are ingested at the grain where they actually live and resolved retroactively, which is how a year of unclassified spend got reclassified in an afternoon without collecting a single new byte. AI assistant spend is ingested from the source billing API and reconciles to the vendor's own export to the cent. And the platform practices what it preaches: it runs on serverless infrastructure tuned so hard that its own bill is about $20 a month.
Billed versus effective cost differed by pocket change across the whole estate: nearly every dollar was running at on-demand rates. On a flat bill that's defensible; on one that grew 75% in five months it's the largest untouched lever, and now it's quantified, owned, and on the roadmap instead of invisible.
AI assistant spend had quintupled in twelve months inside the cloud bill. The backfill made it visible, attributed it to cost centers and named users, and corrected a five-figure double-count before it reached the CFO twice.
Ownerless license seats, untraced developer tooling, and an uncapped pay-as-you-go AI service that went from zero to real money in three weeks: each surfaced, quantified, and routed to an owner or explicitly accepted.
Three required tags, one grain, ratified across finance, IT, and research. Charge-code coverage more than tripled in a day, retroactively across thirteen months, because the fix was reading existing tags correctly rather than demanding new ones.
Cost data fails quietly: loaders that report success while inserting nothing, APIs that cap responses and return 200, gaps that hide behind a true "loaded through" date. This platform treats that as the primary threat. Invariant checks assert properties that must hold no matter which bug appears next; every gap detector must be proven able to fail before it's trusted; provisional data is labeled rather than hidden.
"A check that has never failed is not yet a check."
from the platform's engineering log