hubot-slack-api is a Slack web API call extension for Hubot that adds new methods to your robot instance, under robot.slack. Each API call lives in a subobject corresponding to the first part of the API call name, so for example channels.list is robot.slack.channels.list(). Each method has the signature function(args, callback). The argument object keys should be API argument names, and the callback should have the signature function(err, res). If the callback is omitted a bluebird Promise is returned.
The API key is read from either the HUBOT_SLACK_TOKEN environment variable that hubot-slack uses, or – if you want to use a separate API key – you can either use the HUBOT_SLACK_API_TOKEN env variable or give the token in the token key in the argument object.
To use it, run npm install --save hubot-slack-api and add hubot-slack-api to your external-scripts.json.
slackage is a command line tool for making Slack web API calls (and not just message sending, but the whole API is supported). Read more here.