Summarized from https://discuss.circleci.com/t/organization-wide-webhooks/2200 :
Currently we are setting the same webhook for many projects. It would be handy to have an option for organization-wide webhooks, that is, webhook notifications that apply to every project of the organization.
As an example we currently set the exact same Slack hook for every project, and it is very easy to forget doing that when adding new projects. GitHub introduced the exact same feature a while ago and it’s been an incredible help for us.
A related feature has been released, which may make this easier for some teams. Webhooks can now be configured via API, although still per-project vs per-org. Learn more in the API docs: https://circleci.com/docs/api/v2/#tag/Webhook
Our current thinking on this is that we are looking at adding some mechanism to have configuration that can cascade into pipelines and/or dynamically generate config from the org or project level. That would let you effectively add your webhooks at the org level without having to build new notifications infrastructure.