Flipper cannot be opened because the developer cannot be verified in macOS Catalina

Flipper is a platform for debugging iOS, Android and React Native apps. I have downloaded the Flipper app from https://fbflipper.com/, but I can't run it.

macOS version: Catalina 10.15.3

Just Right Click > Open. Or alternatively, open System Preferences, Security & Privacy, General tab, and Click 'Open Anyway'. Guide on support.apple.com

• Still not working?: Right Click > Open, again. If you don't have certain permissions on your mac (for example on your work laptop), you'd need to run xattr -d com.apple.quarantine /Applications/Flipper.app instead.

Problem

• This is a general problem (security feature called Gatekeeper) with apps on macOS where the developer is not registered with Apple (Paying $99/year) and so has not notarized their application. Specifically, Gatekeeper saves a quarantine flag on a downloaded file. So alternatively, you can remove this flag for your specific file, or disable Gatekeeper entirely so you never have this issue again.

• A nice explanation by the Terraform team who faced the same issue:

  Indeed the new version of MacOS is stricter about running software you've downloaded that isn't signed with an Apple developer key. Terraform distributions are signed with a HashiCorp key with signatures distributed out of band on releases.hashicorp.com, but MacOS Catalina is requiring participation in Apple's developer program specifically, and Terraform is currently not built to support that. source

• From an app developer stand point: Applications on macOS need a Developer ID certificate to verify that we are trusted developers. This also provides access to macOS capabilities: e.g. CloudKit, Apple Push Notifications. If you're making an app, you can need to go into developer.apple.com to create an Apple Developer ID certificate, or create on in XCode (in some cases).