We rewrote JSONata with AI in a day, saved $500k/year

> For something so core to the business, I'm baffled that they let it get to the point where it was costing $300K per year.

And this, this is the core/true/insightful story the executives will never hear about.

I'm the author of the blog post. I'm honestly loving the discussion this is generating (including the less flattering comments here). I'll try to answer some of the assumptions I've seen, hopefully it clears a few things.

First off - some numbers. We're a near real-time cybersecurity platform, and we ingest tens of billions of raw events daily from thousands of different endpoints across SaaS. Additionally, a significant subset of our customers are quite large (think Fortune 500 and up). For the engine, that means a few things:

- It was designed to be dynamic by nature, so that both out-of-the-box and user-defined expressions evaluate seamlessly.

- Schemas vary wildly, of which there are thousands, since they are received from external sources. Often with little documentation.

- A matching expression needs to be alerted on immediately, as these are critical to business safety (no use triggering an alert on a breached account a day later).

- Endpoints change and break on a near-weekly basis, so being able to update expressions on the fly is integral to the process, and should not require changes by the dev team.

Now to answer some questions:

- Why JSONata: others have mentioned it here, but it is a fantastic and expressive framework with a very detailed spec. It fits naturally into a system that is primarily NOT maintained by engineers, but instead by analysts and end-users that often have little coding expertise.

- Why not a pre-existing library: believe me, we tried that first. None actually match the reference spec reliably. We tried multiple Go, Rust and even Java implementations. They all broke on multiple existing expressions, and were not reliably maintained.

- Why JSON at all (and not a normalized pipeline): we have one! Our main flow is much more of a classic ELT, with strongly-defined schemas and distributed processing engines (i.e. Spark). It ingests quite a lot more traffic than gnata does, and is obviously more efficient at scale. However, we have different processes for separate use-cases, as I suspect most of the organizations you work at do as well.

- Why Go and not Java/JS/Rust: well, because that's our backend. The rule engine is not JUST for evaluating JSONata expressions. There are a lot of layers involving many aspects of the system, one of which is gnata. A matching event must pass all these layers before it even gets to the evaluation part. Unless we rewrote our backend out in JS, no other language would have really mitigated the problem.

Finally, regarding the $300k/year cost (which many here seem to be horrified by) - it seems I wasn't clear enough in the blog. 200 pods was not the entire fleet, and it was not statically set. It was a single cluster at peak time. We have multiple clusters, each with their own traffic patterns and auto-scaling configurations. The total cost was $25k/month when summed as a whole.

Being slightly defensive here, but that really is not that dramatic a number when you take into account the business requirements to get such a flexible system up and running (with low latency). And yes, it was a cost sink we were aware of, but as others have mentioned - business ROI is just as important as pure dollar cost. It is a core feature that our customers rely on heavily, and changing its base infrastructure was neither trivial nor cost-effective in human-hours. AI completely changed that, and so I took it as a challenge to see how far it could go. gnata was the result.