This legacy integration for Trello works by running a script that communicates with the Trello API in a cron job. We recommend the new Trello webhook integration (which will eventually replace this entirely). Please report any issues which cause you to prefer this integration over the webhook integration.

First, create the stream you'd like to use for Trello notifications, and subscribe all interested parties to this stream. We recommend the name trello.

Next, download a copy of trello-to-zulip and follow the instructions in README.md. When you make changes in Trello, they will be reflected in Zulip:

Thanks to Nathan from FoundationDB for submitting this integration!