runtypes VS io-ts-transformer

In terms of which runtime checker I should use. The first tutorial I saw suggested 'Zod', doing a bit more searchign yielded other options such as 'runtypes'.

Runtypes would probably be a better example.

this has been solved by several packages, runtypes https://github.com/pelotom/runtypes being my favorite

I personally like https://github.com/pelotom/runtypes because it bundles your Schema Info and the corresponding Typescript types

When I have to deal with data from API calls, I usually use a runtime typing library like Runtypes or Zod to check the responses at the boundary. These libraries can automatically give you TS types (using their static or infer utilities) to use throughout the rest of the project.

Also runtypes and (as mentioned below) zod.

Seconding the recommendation to use a library for this. runtypes and io-ts are two other alternatives.

I wouldn't reinvent the wheel: https://github.com/pelotom/runtypes

What does your library provide that others don't? For example: https://github.com/colinhacks/zodhttps://github.com/hapijs/joihttps://github.com/jquense/yuphttps://github.com/gcanti/io-tshttps://github.com/pelotom/runtypeshttps://github.com/sindresorhus/ow

You can use the plugin https://github.com/awerlogus/io-ts-transformer with https://github.com/cevek/ttypescript to get compile time generation of io-ts codecs as well.