You don't have to start from scratch. Whatever you've got in plain text files, in Markdown, or in the export from your current notes app — it comes with you.
Almost every notes app exports to Markdown or HTML, and if you've kept your notes in plain .txt files for years, there's nothing to convert at all. OttaNote reads all three.
You pick the files — one, or a whole folder of them, mixed together is fine — and choose where they go: an existing folder, or a new one you create on the spot. Each file becomes a note, with the file name as its title.
From Markdown and HTML, your formatting comes with it: headings stay headings, lists stay lists, and - [ ] becomes a checkbox you can click. We read a .txt file literally, so a # or a * stays exactly as you typed it. We do make web addresses clickable, and every line becomes its own paragraph.
For a single note, you don't need to make a file at all. Paste Markdown or formatted text from a web page into a note, and OttaNote asks whether to turn it into headings, lists and checkboxes, or leave it as raw text. That often saves the whole detour through an export.
Evernote exports a whole notebook as a single .enex file, and we read that format directly: one such file becomes one folder in OttaNote, with all the notes in it. So there is no need to save everything separately first.
You export your notebooks and select them all at once. You then see what's in each notebook, untick anything you don't want to bring, and set the folder name before you start — handy, because Evernote hands them over as Notebook (1).enex. Each notebook becomes its own folder; any single notes you exported go together in one place.
Your formatting comes with it — headings, bold, italic, colours and links — and checkboxes come across too, including their nesting and whatever you'd already ticked. PDFs and images attached to a note come along as attachments. The created and modified dates are kept, so your archive keeps its timeline and you don't suddenly have a thousand notes dated today.
However you bring them in, OttaNote recognises notes you already have by their title and content. For each one you choose what happens: skip it, add it anyway, or move the existing note to the import folder. Tick one box and the rest of the duplicates follow the same choice. You can stop halfway, so you can switch over in stages, or redo an export when you can't remember what was in it.
The free plan goes up to 50 notes and 50 MB of attachments. If your archive is bigger, you'll need Plus: € 29.99 a year or € 3.99 a month, or a one-time lifetime (launch price from € 29.99). So it's worth checking how many notes your export contains before you start.
It all comes back out again, too: Markdown, HTML and PDF — per note, per folder, or all at once as a full backup to your own device.