You can give a try to Hurl [1], a CLI open source tool, based on plain text and curl. It allows you to run and test Rest/SOAP/GraphQL APIs (I'm one of the maintainer).
There is no GUI, so Hurl is not a drop-in Postman replacement, but it has nice features: it can be easily integrated in CI/CD, it's fast and it's powered by curl!
A detail: Hurl is given to the community by Orange, a French telco. Orange is not in the dev business, so it should remain free, open source, analytics free for a long time. In any case, you can easily convert Hurl files to JSON [2] in order to switch to another tool or not being trapped in a single provider...
[1]: https://hurl.dev
[2]: https://hurl.dev/docs/frequently-asked-questions.html#how-ca...