What is the best workflow to sync two TODO.TXTs edited on two different devices?

[tempuserr]

On two different devices (PC and Android) I use 2 different apps to maintain Task List (Sleek on PC and Simpletask on Android).

What is the best way to sync (merge) this todo.txt Lists when edits (e.g. adding new tasks, completion others, changing due dates, deleting, etc.) ale done on both of them independently?
Is it possible for this kind of two-way sync?
What is the best automatic method or software to do this?

[jbtodo]

Is this an ongoing sync between different files or do you just want to sync them up once and then use a single todo.txt file?

For the second case, I have had good luck with Dropbox (free account) using Sleek and SwiftoDo on iOS (not sure what is the comparable Android app). I can edit on both (just not withing seconds of each other... and they sync up just fine.
If it is a onetime sync, that is the beauty of txt files, you can just copy paste everything together and then clean it up on your preferred platform.

[tempuserr]

I mean ongoing sync.
I adding task on my Android phone when on a road and on Windows when working at computer.
So my task gets different on both lists - some can be common, but another tasks are only on one of this two lists.

There is an article which shows what is a main issue with todo.txt: https://rtalbert.org/back-to-todoist/
Unfortunately I agree with that - there is not a reliable ongoing two-way sync of todo.txts at the moment. As far I have researched for it.

Of course it is possible to make it - comparing two text files is not a rocket science, but this needs to be built into clients or added to some kind of network/server service which merge two lists when clients connects to it. So this is task rather to senior programmer.

[mshuflin]

I use synching for this

[tempuserr]

Syncthing can merge different lines from two different text files and merge it into one??

[mshuflin]

If you have syncthing syncing the whole time, it does not need to merge anything

[tempuserr]

Maybe it will work for people with all devices permanently turned on and online, who don't leave one big city.
As described in above linked article it will not work in other cases (traveling, flights, mountain trips, etc.) for others, and I'm in this group.

But thanks for a tip, maybe this would be a solution for users from first group.