We are big fans of Slack and have been using it for a while now. Our friends at Vizzuality started using it recently and we missed not being able to speak with them. We started with a light integration with Slack using 4 webhooks and this project.

This gave way to better way to share channels across between slack teams: slackline.io

You can try it for free joining our #slackline shared channel

The free version is a light integration with the Slack API just using incoming and outgoing webhooks.

slackline.io allows you to:

• See the avatars from the users in the other team.
• Easier to setup: create your shared channel, share the URL to the shared channel with somebody in the other team and they can connect their team by themselves. No need to exchange tokens or manually craft URLs.
• Support for more than two teams connected to the same shared channel.
• Any team can change the channel they are using with no need to change anything in the other teams.

slackline.io is still under development, but you can try it for free connecting to our #slackline shared channel and we'll notify you as soon as it's available.

We would obviously recommend you use slackline.io since it's easier to setup and seeing avatars from those on the other side really rocks. But, if you want to use this version, that's cool with us too! :)

You just need to follow the following steps to setup a channel.

1. Create a channel you want to share with another team.
2. Create an Incoming WebHook integration and select the channel you created.
3. Copy the Incoming WebHook token (you can find it in the left column from the integration page).
4. Create a URL with the following format: http://slackline.herokuapp.com/bridge/?token=[TOKEN]&domain=[YOUR_SLACK_DOMAIN] send it to the person setting up the other team.
5. The person setting up the other team will send you a similar URL with their domain and token, create an Outgoing WebHook with that URL and the channel you created in step 1.

Once you have done this in both teams, you will have a chat-room shared by both teams.

Here you have an example of a Outgoing WebHook URL:

http://slackline.herokuapp.com/bridge/?token=bcaa5867b1d42142b74eDVA4&domain=avengers.slack.com

We are just bridging hooks, we don't store any messages going through the bridge.

This project is not officially supported by Slack and they are not responsible for the use you make of this and won't give you any support related to this integration.

Now that we are talking disclaimers... I'm not responsible either for any use of the software. Use at your own risk and to be safe it might be good if you deploy this yourself rather than using my Heroku deployment ;)

Copyright (C) <2014> Ernesto Jimenez erjica@gmail.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.