Please note that this is not a complete list of all online resources.

Genuki

https://www.genuki.org.uk/big/eng/GLS

Registration districts for the whole of England and Wales - you can easily click on the Gloucestershire link. :smile5;
https://www.ukbmd.org.uk/reg/index.html

Or, if you already know the name of the district, here's an alphabetical list of the districts in England and Wales.
https://www.ukbmd.org.uk/reg/districts/index.html

FamilySearch - you have to register, but it's free to use.
https://www.familysearch.org/en/

FreeREG - transcriptions of parish registers. An on-going project, who are always looking for volunteers.
https://www.freereg.org.uk/

FreeCEN - transcriptions of the census 1841-1861. An on-going project, who are always looking for volunteers.
https://www.freecen.org.uk/

British Newspaper Archive
Can't remember if you have to register to search, but searching is free.
All but the latest updates to the BNA are also available on Findmypast.
https://www.britishnewspaperarchive.co.uk/

Ancestry and Findmypast (FMP) both have what are called 'library editions' which are available for free through your local library. Not all counties provide this service, and although some allow you to sign in on your home computer, at other libraries you have to visit in person.
Not all of the datasets are available on the library editions.

Ancestry datasets

Bristol, England, Non-Conformist Baptism, Marriage and Burial Registers, 1644-1981
Bristol, England, Church of England Baptisms, 1813-1918
Bristol, England, Church of England Baptisms, Marriages and Burials, 1538-1812
Bristol, England, Church of England Burials, 1813-1994
Bristol, England, Church of England Marriages and Banns,
Gloucestershire, England, Church of England Marriages and Banns, 1754-1935
Gloucestershire, England, Church of England Baptisms, 1813-1913
Gloucestershire, England, Church of England Confirmations, 1834-1913
Gloucestershire, England, Church of England Burials, 1813-1988
Gloucestershire, England, Prison Records, 1728-1914G
Gloucestershire, England, Church of England Baptisms, Marriages and Burials, 1538-1813
Gloucestershire, England, Electoral Registers, 1832-1974
Gloucestershire, England, Land Tax Records, 1713-1833
Gloucestershire, England, Wills and Inventories, 1541-1858


FMP datasets

Gloucester Apprentices 1595-1700
Gloucestershire Baptisms 1695 – 1801 (but only eight parishes select from list)
Gloucestershire Burials 1696 – 1801 (but only eight parishes select from list)
Gloucestershire Marriages 1697 – 1801 (but only eight parishes select from list)
Gloucestershire Registers & Records
Gloucestershire Wills & Administrations, 1801-1858
Gloucestershire, Bigland's Monumental Inscriptions
Gloucestershire, Bristol Baptism Index
Gloucestershire, Bristol Burial Index
Gloucestershire, Bristol Marriage Index
Gloucestershire, Cheltenham Probate Abstracts, 1660-1740