Show HN: Callosum – A smarter OpenAPI editor/client (opens in new tab)

A couple years ago I was really frustrated by Postman, it couldn't do basic JSON schema validation, and didn't interoperate well with the OpenAPI spec I had to use for serverless deployments. On top of that, they started requiring an account and cloud sync, and other things I just wasn't comfortable with.

So what's an engineer to do? Build yet another API Client of course! [0] It's still fairly rough and crashes more often than I like, but it's basically at the point that I've switched most of my usage so I figured I would rip off the bandaid and do a Show HN.

Short list of some of the (IMHO) cool features that you can't do in Postman:

* Generate JSON Schema from request/response data.

* Generate request content template from JSON Schema.

* Reusable Schema components (Analyze->Extract Schemas menu)

* Basic field and JSON validation (so much more to do here!)

* Embeddable environment and encrypted variables [1] in the OpenAPI document.

* From scratch, run a MITM proxy and record API requests, then automatically generate an OpenAPI spec.

* Deep linking w/o a web server.

There's a short youtube playlist of some of these features, but I need to spend some time demoing the rest of them. What is most interesting to folks?

I would love to integrate better with the API doc generation tools but need to figure out how that would look. Speakeasy/Redocly/etc are some great projects and I don't want to reinvent the wheels there.

I would also seriously appreciate some tough love/feedback to make this even better. I'm sure someone smarter than me can pick apart the variable encryption (I broke rule #1 of cryptography and rolled my own, but I couldn't find a similar use case)

[0]: https://callosum.dev/posts/why-build-another-api-client.html

[1]: https://callosum.dev/docs/variable-encryption.html