At least for Rails there are several gems available (ie https://github.com/WeTransfer/ghost_adapter https://github.com/WeTransfer/ghost_adapter or https://githu

At least for Rails there are several gems available (ie https://github.com/WeTransfer/ghost_adapter https://github.com/WeTransfer/ghost_adapter or https://github.com/departurerb/departure https://github.com/departurerb/departure) that seamlessly hook into the existing migration system and will run all eligible migrations through gh-ost or pt-osc as needed. You're right that it's not free but it isn't all that far off either. That said, online schema migrations are a specialized tool designed for very big tables that take hours to run an ALTER TABLE on. If all your tables are small enough that alterations take less than a second or so, don't bother and just block the table for a bit. It's fine.