There are a number of fact-checking sites, with varying philosophies and methods. Many quote and use data from think-tanks and other partial organisations so it is well worth looking at several fact-checking sites, particularly if you are investigating one specific topic.
Generally a good impartial website that tries to present even-handed assessments. The interpretation
A pro EU independent website with a large amount of information and several commissioned articles every day
Holding European national and EU politicians to account in response to specific statements. Farage seems to have a particularly high score for telling porkies.
Wikipedia : “The think-tank was set up by business people and is a proponent of a flexible model for European integration, allowing for EU member states to integrate with each other to different degrees and for powers to also be returned from the EU to member states. Open Europe is an advocate of an economically liberal EU Single Market as well as supportive of the EU’s freedom of movement, but has called for less EU involvement in several other policy areas. It has adopted a neutral stance in the 2016 EU referendum in the UK.”
“The authoritative source for independent research on UK-EU relations”. Funded by the Economic and Social Research Council (ESRC), and based at King’s College London.