The Charities Aid Foundation (CAF) is a registered UK charity that operates in the United Kingdom, the United States of America and Canada. It works with companies, private philanthropists, regular donors, fellow foundations, governments, charities and not-for-profit enterprises to enable them to give more. According to its website, CAF's stated purpose is to "accelerate progress in society towards a fair and sustainable future for all."

In late 2021, CAF was listed by the UK Charity Commission as the country's fourth largest charity by income. It serves as regulatory experts to ensure funds reach charities and social enterprises as quickly and safely as possible via its charity validation which enables effective cross-border giving. CAF also wholly owns CAF Bank, a fully regulated bank that serves more than 14,000 UK-based charities and social enterprises.

CAF claims to be known for its independence, expertise, and international reach, leading an international network of like-minded charitable organisations. CAF Group consists of Charities Aid Foundation and its subsidiaries in the UK including CAF Bank; CAF America; the CAF American Donor Fund and CAF Canada. CAF Group collectively seeks to inspire innovation, share best practice, and improve cross-border giving in support of civil society.

CAF's head office is located in Kent, southeast of London and the charity has a second UK office in central London at St Bride Street, EC4A 4AD.^{[citation needed]}

In addition to offices in the UK, America, and Canada, CAF leads an international network of independent philanthropic organisations in several other countries. They include CAF Southern Africa, Good2Give (Australia and New Zealand), BCause (Bulgaria), IDIS (Brazil), and CAF India.

As well as offering a range of services to charities, philanthropists and businesses, CAF also produces leading research into charitable giving. CAF produces the World Giving Index as well as the UK Giving report – the largest multi-year study of giving behaviour in the UK.

In 1924, the National Council of Social Service set up a Charities Department to encourage efficient giving to charity. This department was later renamed the Charities Aid Fund while the National Council of Social Service became the National Council for Voluntary Organisations (NCVO). The Charities Aid Foundation took its current name in 1974 when it became a fully independent organisation.

CAF provides services to charities, businesses and individuals in the UK and abroad, including help with fundraising, consultancy, and loans and grants.