For security reasons, any request sent with the Fetch capability is routed through Canva's backend. This means the only way to test an app's interactions with a backend is to expose the backend via a public URL.
If you don't have the infrastructure for continually deploying a backend, consider the following options:
ngrok
ngrok is a CLI that exposes a local server via a public URL. It's cross-platform and an account is not required (although a free account has fewer limitations). This is often the simplest and most versatile option.
Some alternatives include:
Glitch
Glitch is a web-based IDE that automatically deploys as you make changes to the code. This means there's no need to bridge the gap between a local and public server. The server is public by default.
Some alternatives include:
webhook.site
For quick and dirty prototyping, webhook.site makes it trivial to:
- Get an endpoint up and running.
- Inspect the incoming requests.
An alternative option is RequestBin.