I have collated a list of providers of standardised assessments below. I have not used all of them, so cannot comment on them.
NFER Tests (only available for primary year groups)
Analysing the data is vital, especially for school leaders, who need to quickly calculate values of key groups, or even for subject leaders who need to identify key students who could achieve that ‘magical grade’ with the right support. Each Key Stage will have different needs and I have created spreadsheets that support the needs of each one below.