Twirp _is_ great. For unary RPC, Connect is similar: using the Connect protocol, it works over HTTP/1.1 or HTTP/2, doesn't require any special networking infra, and has first-class support for JSON payloads. In short, `curl | jq` works again.

To us, the biggest difference is that Connect _also_ supports the gRPC and gRPC-Web protocols. That lets your code interop with a much, much larger ecosystem of tools and systems, many of which are better-supported than their Twirp equivalents.

We designed the Connect protocol and the Go APIs to make multi-protocol support seamless. Server-side code supports the Twirp-like protocol and the gRPC protocols simultaneously by default. Clients can switch protocol with one option, no other code changes required.