Odoo was released as Tiny ERP in 2005, and re-branded as OpenERP in 2009 and as Odoo in 2014. Odoo is a full featured system that tries to do everything - it includes a website builder, fleet manager, event manager, kitchen sink, and so on.
The demo looks really good - they will let you set up and play with an instance for fifteen days, so there is the opportunity to try it out with little initial outlay of time and effort. Configuring such a large system is daunting, though.
WebERP is a lightweight ERP system - one of the design goals is that it is simple, fast and runs on smaller hardware. The main contributor is in New Zealand.
It looks worth investigating further. But there are some problems. It relies on outputting PDF files - presumably for printing - but this shouldn't be to hard to fix. The most worrying thing is that there seems to be a battle of wills amongst some of the main contributors.