I am developer at Teatro.io and I want to offer you our service — it automatically creates a staging server for each opened pull request.
Teatro.io is free for open source projects and some large projects like GitLab, ErrBit, OpenProject, Spree and others are already using Teatro for free stage servers.
Here’s URL of Teatro stage server for my fork of discourse: http://teatro.divineforest-discourse-51d3c00407c3a4a9be8e.ttrcloud.com/
When you connect project to Teatro, we’ll automatically post a comment (via @TeatroIO) with link to unique stage server that was made for this specific branch (see divineforest#3 for example).
To use Teatro you need: — sign in using Github account on https://teatro.io — add your project
Benefits: — demo for new users (always up to date!) — the way to test changes: each Pull Request gets separate stage server — FREE for open source!