How to create biblatex bibliograpy and citation syles

This is a question that comes up from time to time, but I'm afraid there is no comprehensive tutorial for writing biblatex styles at this point.

Some of the introductory materials at biblatex in a nutshell (for beginners) mention a few things that could be interesting to style developers, but there is nothing comprehensive in English. There is a series of two German articles from 2008 by Dominik Waßenhoven in Die TeXnische Komödie about his biblatex style (https://archiv.dante.de/DTK/PDF/komoedie_2008_2.pdf, https://archiv.dante.de/DTK/PDF/komoedie_2008_4.pdf). (Note that the articles are more than 10 years old now, many details have changed since then. The overall approach is still the same, but I expect that there will be new, more elegant interfaces for a few things.) See also the discussion at the end of my answer to Customize biblatex citation style.

If you want to code your own style, the best way to start is to look at the code of the standard styles in

• biblatex.def
• standard.bbx

and a base style you like, say,

• authoryear.bbx
• authoryear.cbx.

See What is the location of the biblatex citation style files? and Editing a citation style (verbose-ibid) for more details on where to find the style file. See also the first part of Customize verbose citation style.

You can also look at some of the styles on CTAN, but keep in mind that styles implementing more complex guidelines (like APA or Chicago style) may have to be quite complex to implement the rules to the letter.

The manual documents all commands defined by the biblatex core, but it does not document all style decisions and style-level (bibmacro) definitions. Because of its length and structure it is often more useful as a reference to look up what exactly a certain command or option does rather than as a guideline to help you write a style.

A great way to get started is Guidelines for customizing biblatex styles and you will find countless questions and answers about modifying biblatex styles on this site already.

If you get stuck, just ask a new question about the problem you are facing. Please try to make your question about specific one particular bit of the style and include a concise example document as well as clear descriptions of the desired output.