Have a look at my NHunspell implementation (mentioned above as https://www.helpandmanual.com/downloads_delphi.html, but it's on SourceForge as well): https://sourceforge.net/projects/nhunspelldelphi/files/
It is a wrapper for NHunspell for Delphi 2007 up to the latest versions. And it includes a wrapper class for Addict v4 dictionaries.
Hunspell is great, because it's open source and can use numerous dictionaries from OpenOffice. But Hunspell alone is missing a parser for the classes/controls used by many Delphi developers. Like a TRichview, just to name an example.
The Addict spell checker is great, because it is a solid spelling checker with a full-fledged parser, has been around for quite a while and it enjoys support for almost every Delphi control you can think of. Just the dictionaries delivered with Addict were never really good.
My goal back then was to combine the two, without having to rewrite everything spelling-check related. We keep using Addict as the spelling checker for everything it was used before. But we don't use the dictionaries. The component comes with an ad3MainDictionary.pas unit (which is, in fact, for Addict 4) and implements a new TMainDictionary (the Addict dictionary class), which redirects the generic functions to Hunspell. The unit needs to replace the original unit from Addict, or take precedence in your search path. The main dicts can be mixed with custom user-defined dictionaries from Addict and the spelling check function is fully transparent. The wrapper has been approved by Addictive Software for inclusion into the open source distribution, because this part of the package is actually not fully open.
What it does
Implements Hunspell for Delphi 2007 and up.
Takes .OXT files as dictionaries, no need to unzip them. A simple zip reader and XML parser is part of the distribution.
Supports spelling and hyphenation dictionaries (no Thesaurus)
Optionally introduces a TMainDictionary wrapper to use it with the Addict Spelling checker
So, if you have been using Addict (you need an Addict license, to use the Addict wrapper) you have the best of both worlds with this implementation. You can use Addict as your spell check engine without many changes, but run it with OpenOffice dictionaries. The hyphenation part is separate from Addict and needs to be applied manually. All the control parsers that were made for Addict, however, should be working fine.
I haven't bothered to update the component on SourceForge. It has received a few internal tweaks in last couple of years - mostly strange OXT configurations, that we have come across. If you are going to use it, please PM me for an update.