New records of more than 55,000 convicts transported to Australia in the 18th and 19th centuries have gone online for the first time.
They contain details of people who were shipped to Australia and were subsequently pardoned or served out their sentences.
Family history website Ancestry.co.uk said the records could be accessed for free for seven days from 24 January.
The company estimates more than two million Britons have convict ancestors.
The convict registers of conditional and absolute pardons 1791 to 1846, and the New South Wales certificates of freedom 1827 to 1867 have been launched online.
Read more on BBC.