As a last hope, I paid for a license to Notecase Pro in hopes of merging many other note formats into one tool. I regret that. I've wasted a lot of time trying every other app that claims import/export functionality. The elephant in the room is they ALL fail to export to Treepad (.hjt) format files so they can be re imported into other apps such as Essential PIM while using Notecase Pro as the master note keeper/editor. I've tried using second and third generation files and search/replace in raw files (like swaping outline/note/node) and nothing works.
Does anybody know of a separate converter program?

There is an app that does this.

You can import many file formats into Notcase Pro. Including tree outlines with multi nested deep level nodes in tree.

Then export from a file tree outline as OPML. Choose entire document in export.

On an Android phone, tablet or Chromebook install Halna Outliner. Either the cheap Pro version or the free version with ads.

Import the OPML from Notecase Pro by:

3 dots menu (top right of app): File: Import...

At bottom left change drop-down menu default:
Filetype (Treepad .hjt)
To
OPML 2

(N.B. Tthis is not version 2 of OPML but an alternative to Halna OPML 1 original, though imports most OPMLv1 & v2, there are numerous flavors as in markdown)

Now you can export as Treepad .hjt which will be imported fine into many apps including back into Notecase Pro itself, Treepad etc.

3 dots menu: File: Export
At bottom left drop-down menu default Export Filetype is Treepad .hjt

https://play.google.com/store/apps/developer?id=halna

Thank you.
I'd already been there done that -- I thought.
What you suggested works fine getting it into plain text in Halna by selecting OPML v2 in Halna. My mistake was following another step -- NoteCase Pro can also be set to save in OPML v2.0.
So, IF anybody else sees this -- don't do it or you'll lose compatibility (like I did, wrongly). You only loose RTF and images coming back to TreePad. I can add RTF and colors back in after updating the text.
The method below is ONLY for staying with OPML 2. It results in a corrupted .hjt file otherwise.
--------------------------------------------------------------------------
Can NoteCase Pro Export and Import OPML v. 2.0?
OPML Export and Import by NoteCase Pro defaults to OPML v. 1.1. To switch the OPML support to OPML 2.0 requires manual editing of the notecase_pro.ini file. The steps for the switch are:
1. Look up the location of the .notecase directory on your system in .notecase Directory.
2. Make sure that you have a plain text editor installed that supports UTF-8 character encoding without byte order marking ("BOM"). See Choosing a Plain Text Editor.
3. Close NoteCase Pro.
4. In your plain text editor, navigate to the .notecase directory and open the notecase_pro.ini file.
5. Add the following lines at the end of the file:

        [OPML Format]
        Version=2.0
        Title_Field=text
        Content_Field=description

6. Save the file.
7. Relaunch NoteCase Pro.
NoteCase Pro will now import and export OPML 2.0 files by selecting OPML as the format in the Import and Export dialogs. IF importing into Android Halna AND the article part does not show then go back to Version 1.1
**To switch back to OPML 1.1, repeat the steps above but in step 5, search & delete the specified lines.

I'm in the same boat as you so maybe can help you out a little. I use EssentialPIM along with other information managers and was searching for the same thing you were. I think I've tried them all, like a lot of others here. Currently I'm using EPIM, NoteCase Pro Windows and Android, RightNote and InfoQube.

There are two programs I found that export (or are native) to TreePad format nicely, but not sure what you need in an Information Manager.

The first one is obviously TreePad.

The second one is MyInfo Pro. It exports perfect TreePad .hjt files that import easily into EPIM, which it seems like you want to do. EPIM doesn't export notes in tree format easily though.

Like I said you didn't mention what you wanted in an Information Manager that does export to TreePad. Like many others here, I wish I could combine parts of every IM I use or tried to make the perfect program, but there doesn't seem to be just one.

I'm curious why you thought that NoteCase Pro exported Treepad files. I thought I was missing something so checked it out this morning but couldn't find anything that mentions it or any option to do this. Did you check out the Trial version? NCP does import TreePad files nicely but I didn't see anything about exporting

Thank you to washere and LB.
The Elephant in the Room I referred to is that for years people have complained about the lack of STANDARD tree/outliner file IMPORT AND EXPORT formats. They all claim to import many formats BUT fail to export to 'some standard' and refuse to improve over the years. It's Black Hole thinking that says 'import everything and don't let it back out'.

Yes, I saw that NoteCase Pro doesn't promote Exporting to Treepad (.hjt) format, but it appeared from the trial version that maybe one of the export formats would be a clean bridge to other apps. NoteCase Pro has some other advantages over TreePad Plus that I hoped would win out in my outline/note consolidation process. However, the Export of NoteCase Pro to HTML, MD, and OPML both version 1.1 and 2.0 to Android Halna (which I really like on Android but no Windows equivalent) introduces unrecognized characters when Exporting Halna back to Treepad format to then be sent back to Windows to import into Essential PIM (which I don't love either due to bugs). But, I hate Microsoft and Google worse. A tedious process when done frequently. It's looks like I will be going back to TreePad Plus in spite of missing lower priority features (I'm also exploring going back to KeyNote NF because it has the needed features, although it's going obsolete).

I'm retired now, but I used to test major software projects and wrote code to automate a wide scope of the process (i.e., White/Black Box, GUI, load testing, user acceptance tests). So... I tend to hold critical views about software not responding to long standing customer's needs. Back when working my go-to Information Mgmt. tools were TreeDBNotes and InfoCube to keep track of rapidly changing details and status on many sub projects merging into larger projects. Now those have gotten better but much harder to justify the expense for my retirement needs (like consolidating and updating many other notes/outlines into one tool/format) and then importing the most current/prioritized stuff into a calendar type app with reminders/sub tasks/note details, etc., that is also not part of NoteCase Pro.

So, in my awkward way, I was asking NoteCase Pro to add functionality to ALSO Export to the defacto TreePad file format that can be easily be imported into calendar apps like Essential PIM.

Thanks again for your responses.
Larry W.

Yes productivity apps do more imports Filetype formats than exports, to stop people going elsewhere I guess. In fact more exports would make them more successful.

Unfortunately there will be no Halna for Windows as he does it in his spare time. Works even better on a Chromebook. There are good Chromebooks now half the price of Pixel and Samsung Pro and of similar quality. Older good ones are much cheaper too second hand. Battery lasts all day.

You might want to try converting the Notecase opml export to other txt formats. Maybe Unicode utf8 and other txt formats in another app, MS Word etc. Might fix the problem, same test with halna output. I never had that problem importing Notecase opml. Opml 2 (minimal, so imports exports most v1 & v2 flavors) format for halna app was my spec.

You might want to make a little opml export file from notecase, few nodes and one node maybe with 3 sublevels, and send it to PIM essential dev. Just a few lines of texts, each line a few words, one node with multi lines for data.

He should have an opml import in this day and age anyway and the devs usually have no allergy to import formats as long as it's easy. And opml is easier than Treepad or keynote filetypes he's done. You might contact the Notecase dev too and ask what format opml txt his export is if you can't figure it out yourself. He's a nice guy too.

All the best.

WOW and Thank you again to washere and LB.

I'm happy to report, I'm not such a grouchy old man now !!!
The recommendation to MyInfo Pro so far is looking like a HOT TIP. So far, It's looking like it does EVERYTHING I hoped. It is maintaining ALL the structure, RTF, and colors I hoped for without lots of fuss.

I'm OK with using tables in the article/note pane when I need that for checkboxes or prioritizing lists. It even has a calendar that I haven't tried yet, but the TreePad Plus note imports into Essential PIM seem to be PERFECT. It'll be worth buying and going back to my conversion process.

Oh yea, I had tried the UTF-8 combinations. One remaining thing I haven't retested is that I had lots of recipes in TreePad Plus formats where apparently there was the single character symbols for fractions (like 1/2 cup) that messed up but I have already gone through my favorites to change to three character fractions.
Thanks a bunch !
Larry W.

Glad to help. One thing I test a lot with all the different IM's is the export / import capabilities. I have lots of bridges between IM's to get the info from one to another.

I thought I'd mention also that since you own a license to NoteCase Pro to try posting on their forum and ask if there's a script that can be adjusted or created to export to TreePad format. The guys there are pretty awesome about helping out and guiding you along. I had a problem with the exporting and importing and Miro, Paul and Daniel jumped on to help within a day. They even guided me along with questions I had about scripting in Lua and sent their own information for me to use. It's really great to see a forum where they help so much. Just like Pierre at InfoQube, that's another really helpful and nice guy and forum. And of course this forum. I found out so much just from reading a lot of the posts.

I use the Windows and Android versions of NCP and have made that my main IM I'm using. It's fast and works great with Android (even encryption). Now I pretty much use that for notes and barely touch EPIM notes. But I still love trying and using all the other IM's I can get my hands on.

Have a good one,
Larry