Although not free, there's a cheap (~5$) option - Data Transformer (disclaimer - I'm its developer). It converts between CSV, JSON, XML, and YML locally.
It offers a number of conversion settings (with sensible defaults) so you can match the data for your purposes.
You can check it out on the Mac App Store or the Microsoft Store.
Have you looked at kiki (https://sources.debian.org/src/kiki/0.5.6-8.1/). It's written in Python and uses wxPython, so likely could be run on numerous platforms. It's in Debian repositories, and possibly other Linux versions.
You can install Calibre eBook (which has a GUI) and use it exclusively from the Command Line &/or the APIs for integration with VIM, etc. and there is no reason other than performance & roaming that you could not have the library located on a network share.
You can certainly add your own plug-ins to customise behaviour, search, etc.
Free, yes & ...
It might not be the best application for your intended plans, though you could use taskwarrior:
For the listed groceries task you could either:
create a list of template tasks for the activities you mentioned, then add the user defined attribute UDA and specify their datatype e.g.
task config uda.grocery_item.type string
task config uda....
Create the file you want as a template. Then create a Batch file as follows. I'm using the "chores" as an example:
for /f "tokens=2 delims==" %%a in ('wmic OS Get localdatetime /value') do set "dt=%%a"
set "YY=%dt:~2,2%" & set "YYYY=%dt:~0,4%" & set "MM=%dt:~4,2%" & set "DD=%dt:~6,2%"
copy chores chores%YYYY%%MM%%DD%.txt
Are you looking for a tool to run regular expression searches or to help develop & test the regex?
Cross Platform Regular Expression Tool
I am a big fan of Robert Kern's python grin tool/library.
Once you have python installed on your system just run:
pip install grin3 or for python 2 installations leave out the 3
What it does
On my side I always use this Chrome App.
It is very simple and light and it support the few things I need (multiline, highlight and replace). The big plus against the online tool regex101 is that once installed on your chrome browser, you can use it without need of Internet connections.
When using an IDE, you cal also install plugins into:
IntelliJ IDEA: ...
Possibly, for August, 2019 there are no programs suitable for all @Doug requirements.
In section “Suggestion” I suggest alternatives. See “Problems” section, to find out what disadvantages of these alternatives do I consider significant.
This answer is relevant for 19 August, 2019. In the future data of this answer may be ...
In case anyone chances on this question from a search engine, I found an answer.
fx is a command-line utility that allows TUI-style interactive browsing of JSON data. You can fetch that package through NPM or download a binary from the link.
Try dupeguru from here: https://dupeguru.voltaicideas.net/.
In Picture mode it checks for similar images, even though they have different sizes, it has a threshold setting, creates groups of similar files, choosing the biggest file as main, but can be set another file for reference too. Is able to move files to some path or to the recycle bin or delete them ...