use only initials for author name in bibliography

Update

If you want to abbreviate given names, use the giveninits option (which in older versions of biblatex was called firstinits). That option does not influence maxnames and friends, so has no influence on whether or not a list of names is shortened with "et al.".

documentclass[british]{article}
usepackage[T1]{fontenc}
usepackage{babel}
usepackage{csquotes}

usepackage[style=numeric, maxbibnames=99, giveninits]{biblatex}


addbibresource{biblatex-examples.bib}

begin{document}
Lorem autocite{sigfridsson,worman,geer,nussbaum,aksin}

printbibliography
end{document}

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It is quite unusual to abbreviate the family/last names of people in the bibliography, but Biber already provides abbreviated family names, we just have to use them.

For initials of given names there is a simple option called giveninits and while a similar option exists for the family name it doesn't do anything with the standard styles. So here we just define a new name format and use that.

documentclass[british]{article}
usepackage[T1]{fontenc}
usepackage{babel}
usepackage{csquotes}

usepackage[style=numeric, maxbibnames=99]{biblatex}

DeclareNameFormat{given-f}{%
  usebibmacro{name:given-family}
    {namepartfamilyi}
    {namepartgiven}
    {namepartprefixi}
    {namepartsuffix}%
  usebibmacro{name:andothers}}

DeclareNameAlias{default}{given-f}

addbibresource{biblatex-examples.bib}

begin{document}
Lorem autocite{sigfridsson,worman,geer,nussbaum,aksin}

printbibliography
end{document}