ArkType is a really interesting library that has a difficult time marketing itself. More than being a schema validator, it brings TS types into the runtime, so you can programmatically work with types as data with full fidelity.

I've been evaluating schema libraries for a better-than-Zod source of truth, and ArkType is where I've been focused. Zod v4 just entered beta[1], and it improves many of my problems with it. For such a mature library to improve like this, v4 is treat and speaks volumes to the quality of engineering. But ArkType has a much larger scope, and feels to me more like a data modeling language than a library.

The main downside I see is that its runtime code size footprint is much larger than Zod. For some frontends this may be acceptable, but it's a real cost that isn't wise to pay in many cases. The good news is with precompilation[2] I think ArkType will come into its own and look more like a language with a compiler, and be suitable for lightweight frontends too.

[1] https://v4.zod.dev/v4

[2] https://github.com/arktypeio/arktype/issues/810

V4 of zod landed recently and it promises better perf https://v4.zod.dev/v4