Not strictly a 'GUI' wrapper, but there are some interactive HTTP clients, which features like autocomplete: [1] https://github.com/eliangcs/http-prompt https:

Not strictly a 'GUI' wrapper, but there are some interactive HTTP clients, which features like autocomplete: [1] https://github.com/eliangcs/http-prompt https://github.com/eliangcs/http-prompt, built on HTTPie [2] https://github.com/cloudhead/http-console https://github.com/cloudhead/http-console, on Node.js