MDSTUDIO
A Markdown editor for writers and developers who want to write, preview, present and share a document without creating an account.
Reading or sharing a document shouldn't require an account, and writing, previewing and presenting are different jobs that one screen does badly.
The key decision was to put the shared document in the link itself. The text is compressed and stored in the part of the URL that browsers don't send to a server, so no server ever holds it. The tool is plain about the cost: anyone who has the link can read it, because compression is not encryption.
It has Edit, Split and Preview modes, plus Zen, Focus, Presentation and print to PDF. The preview handles GitHub-style Markdown with maths, diagrams and footnotes. Fonts, accent, width, spacing and code theme can be changed, and the sound effects and desk pet are strictly opt-in.
Documents live in one of two places: the browser, or a folder on your computer. Each tracks what is saved and what isn't. Saving to a folder only happens when autosave is on, a folder is connected and something has changed, after a short pause. Folders work only in Chromium browsers, and the error says so and suggests one.
The limit: a damaged or truncated link fails to open without any message, long documents make very long links, and the diagram rendering path still needs testing, because a shared link carries someone else's content.
Next I would add a clear error when a link can't be opened, warn when a link gets too long, and test diagram rendering with hostile input before calling sharing safe.