Font is to light and faded, hard to read.

Seems like a fairly capable tool, but interface is awkward. Can only add a single header at a time. Presentation is a little primitive. Otherwise, I like that it's open to customizing the request. "OK" button being spelled "Okay" is unconventional and the request and response headers being displayed in different formats is a bit annoying. Would be nice if common/necessary headers like Authorization and Content-Type had a dedicated input area, even if it was just a textbox for bulk entry. Generating an equivalent CURL command is a very nice touch.

Todo muy bien, pero quedaría excelente con un tema oscuro, por favor aplíquenlo, es lo único que le falta :(

Please do not use existing session cookies for requests. Out of a developer's perspective, this is a little confusing. Apart from that, I like your tool. Pretty easy, mostly enough features, but not as overpowered as Postman for instance.