I wrote this library this weekend after realizing that Zod was really not designed for the use-cases I want JSON schemas for: 1) defining response formats for LLMs and 2) as a single source of truth for data structures.
Zod's validation errors are awful, the json schema it generates for LLM is ugly and and often confusing, the types structures Zod creates are often unintelligible in the and there's even no good way to pretty print a schema when you're debugging. Things are even worse if you're stuck with zod/v3
None of this makes a lot of sense. Validation errors are largely irrelevant for LLMs and they can understand them just fine. The type structure looks good for LLMs. You can definitely pretty print a schema at runtime.
Had you considered using something like XML as the transport format rather than JSON? If the UX is similar to zod it wouldn't matter what the underlying data format is, and XML is meant to support schemas unlike JSON.
JSON Schema is a schema built on JSON and it’s already being used. Using XML would mean converting the XML into JSON schema to define the response from the LLM.
That said, JSON is “language neutral” but also super convenient for JavaScript developers and typically more convenient for most people than XML.
They aren’t people but their interface is more person than machine parser.
Also I don’t think XML is better for machines. JSON is more strict. XML has weird whitespace to make it easier for humans and it has too many ways to represent the same things like an array or k/v pairs.
I often find myself converting XML, TOML, and other formats to JSON just for strict clarity on what is being represented.
This all seems pretty uninformed.
This is actually discussed in the linked article (READ ME file).
most of the claims you're making against zod is inaccurate. the readme feels like false claims by ai.
> This provides O(1) performance
Wouldn’t 1% of N still imply O(N) performance?
That said, JSON is “language neutral” but also super convenient for JavaScript developers and typically more convenient for most people than XML.
We want a format for LLMs or for people?
Also I don’t think XML is better for machines. JSON is more strict. XML has weird whitespace to make it easier for humans and it has too many ways to represent the same things like an array or k/v pairs.
I often find myself converting XML, TOML, and other formats to JSON just for strict clarity on what is being represented.