Beryl Evans from the national library's family history unit with a will
A five-year project to make 190,000 wills available online has been completed.
About 800,000 pages of documents, some going as far back as the 14th Century, have been placed on the National Library of Wales' website.
Among the wills available at the click of a button are Twm Sion Cati's, known as the Welsh Robin Hood, and hymn writer William Williams, Pantycelyn.
Officials said it had taken more than five years to digitise the documents.
The National Library of Wales in Aberystwyth said the wills dated from the 14th Century until 1858, when civil probate was introduced, and 1,000 of them were written in Welsh.
It said the project was "good news for family historians, social historians and the inquisitive".
Beryl Evans describes the contents of some of the more interesting wills available online
A national library spokesman said: "Wills which were proved in the Welsh ecclesiastical courts before the introduction of civil probate on 11 January 1858 have long been deposited at The National Library of Wales.
"An online index and an opportunity to view digital images of these wills within the library building has been available for some time.
"However from today remote users will also be able to view the digital images.
"Amongst the collection is the will of Twm Sion Cati, alias Thomas Johnes, Fountaine Gate, Caron, this year being the 400th anniversary of his death.
"The will of Howell Harris, the famous Welsh religious reformer, can also be seen."
Twm Sion Cati lived between 1530 and 1620 and was from Tregaron in Ceredigion.
In his youth he made his living as a highwayman and was famed for his kindness to his victims.
In later life he became a magistrate and became a member of the ruling classes.
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