Give Well is a research organisation that publishes reports on the effectiveness of charities. They do select a 'Top 9' of best charities for a range of issues

Give Well is a research organisation that publishes reports on the effectiveness of charities. They do select a 'Top 9' of best charities for a range of issues, and also run a 'donation index' where you can allow your donation to be distributed to the top charities (purportedly without a fee being taken). I've heard of Give Well being mentioned on various Stats podcasts (e.g. the BBC's More or Less) and Our World in Data is very reputable.