1. Alternative Dialog Find & Replace for Writer (AltSearch)
The default “Find & Replace” functionality in LibreOffice Writer does more than basic find and replace, and I guess for many users this is more than what they need. However, if you, like me, have more complex find and replace tasks to perform, you may want to check the AltSearch extension.
This extension comes with lots of features such as multiple search and replacement in one step, batch mode, and the ability to search practically everywhere (e.g. bookmarks, text fields, footnotes, endnotes, etc.)
2. MultiSave
If you work with documents in multiple formats – e.g. you write the document in .ODT because this is the format of your choice but need to submit the final version in Microsoft Word format and/or export it in PDF, then you will certainly love the MultiSave extension.
Enter the name of the file and the location you want to save it to. Then choose which formats to save it simultaneously to. This addon is very handy when you need to have the same file in two or all of these formats. For instance, the invoices for a client of mine are in PDF. I write the original in .html, and it’s not unlikely to submit the wrong PDF version simply because I made the changes in the html file and forgot to export them to the PDF one. With this extension the changes are written immediately to the PDF, too.
3. Calendar for Calc
For anybody who frequently has to enter dates in Calc, Calendar for Calc is a great extension. Instead of having to check a separate calendar and enter the dates manually, with this addon you can select range(s) and double click on a day to insert the date in ISO format.
4. Code Colorizer Formatter
I know LibreOffice isn’t meant to be a coding tool, but if you prefer to use it for writing/editing/viewing code, you will love this extension. Code Colorizer Formatter highlights keywords, literals, comments, and operators in BASH, Basic, C++, Java, Perl, PHP, Python, R, SQL, XML, C#, Lisp, Object C, JavaScript, Ruby, 8085 Assembler, and x86 Assembler, thus making it much easier to read the code and make edits.
5. ShowNotes
ShowNotes is an addon that was released more than five years ago, but it still works. It’s a simple extension for Calc that allows you to show/hide all the notes for all cells. This is so much easier than to have to check all the cells with notes one by one.
6. A Spell Checker, Grammar Checker or a Dictionary Extension for Your Language
If you are using languages other than English, check the dictionary extensions to see if there are dictionaries, grammar checkers, spell checkers and other language tools for the language(s) of interest to you. There are language tools for Spanish, French, Russian, German, Danish, Turkish, etc., so just pick the one(s) you need.
There are quite a number of extensions for LibreOffice and not every one is useful. Those that I have included are the more useful ones and compatible with the latest LibreOffice versions. If you expected thousands of LibreOffice addons to choose from, you will be disappointed – there are probably just a few dozen of recently-updated addons. If you are curious to see what else is available, check this list of LibreOffice Extensions. Just be warned that not all of them are recent, and they might not work for your LibreOffice version.