SumizAI vs Markdown Shell Extensions and Editor

What Markdown Shell Extensions and Editor is

Markdown Shell Extensions and Editor (the EtheaDev project) is a free, open-source (Apache-2.0) Windows tool that does one thing well: it lets you edit and preview Markdown files directly from Windows Explorer, without opening a separate app for every .md file. This sits in a completely different category from commercial AI notepads — it's a developer tool, written in Delphi, aimed at people who treat Markdown as a working format rather than just a way to store ai notes content.

The core feature is shell integration: a "Preview Handler" shows the rendered content of a Markdown file right in Explorer's preview pane, without opening an editor — exactly the way PDF or image preview works. On top of that there's a full text editor with syntax highlighting (headings, bold, links, code blocks in multiple languages including Delphi and JSON) and synchronized scrolling between the editor and the HTML preview.

For anyone managing a software project's documentation — README files, CHANGELOGs, technical notes — this tool removes the friction between writing and checking how a fragment will look once rendered. It's not a system for building a large ai notes knowledge base with full-text search or a link graph — it's a lightweight file-system add-on that complements work in Explorer rather than replacing it.

Export to PDF (via the SynPDF library) with clickable hyperlinks preserved is a detail appreciated by anyone preparing documentation for distribution outside the dev environment — a colleague with nothing installed to read Markdown gets a normal PDF file instead. That's the pragmatic approach typical of tools built by and for developers, where the priority is solving one recurring problem well rather than building a platform.

A color theme matched to Windows' light and dark mode is another small but appreciated detail — the tool doesn't stick out visually against the rest of the system, which can't be said for some competing shell extensions.

Compared to full editors like Typora or Mark Text, Markdown Shell Extensions doesn't offer a WYSIWYG mode or cloud sync — its edge is precisely the depth of Explorer integration, something web-based or cross-platform ai notes competitors can't offer by definition.

The Apache-2.0 license and a public GitHub repository mean the project can be audited, forked, and adapted — relevant for organizations that avoid closed system-shell extensions of unknown behavior on principle. That's also a trust signal for a tool that integrates deeply with the OS shell, where trusting the code matters more than for a plain ai notes app running in an isolated window.

The limitation is, of course, the platform — Windows only, no macOS or Linux version, and none of the features typical of modern AI notepads, like summaries or semantic search. That's a deliberate scope choice, not an oversight: the creators focused on solving one shell-integration problem well, instead of spreading resources thin on features that dedicated these notes tools already handle better.

Anyone keeping a project's technical log directly in Markdown files inside a repository will also appreciate the lack of any cloud dependency — these notes content (developer notes, in this case) stays on the local disk and in version control, with no risk of leaking to an external provider.

In short, Markdown Shell Extensions and Editor is a niche but solidly built tool for Windows users who work with Markdown files daily — it's closer to a file-system extension than a full these notes notepad, and it does that niche job very well.

What SumizAI is

A note-taking application built around a conversation with an AI model. You ask a question, the answer streams back, and the answers worth keeping become Markdown notes — filed into a vault that is a folder on your own disk.

A vault is a directory holding base.md, a generated table of contents up to six levels deep, and a notes/ folder with one .md file per note. Before a note is written it is checked against the ones already there, so the fourth note about the same idea gets merged instead of added. Links between notes are ordinary Markdown links to files that exist.

The model is never ours: you bring your own API key to one of seven providers — Anthropic, OpenAI, Gemini, Groq, OpenRouter, a local Ollama or your own server — and pay that provider directly. A question sends the table of contents plus at most five relevant notes within a 24,000-character budget, and the app shows you which five it used.

Every answer kept this way becomes one of these ai notes, ready to search again months later without hunting back through old chats.

Side by side

Where they differ

• AlternativeTo's description of Markdown Shell Extensions and Editor does not mention an AI model. That is the whole starting point in SumizAI: you have a conversation with a model on your own API key, and the answers worth keeping become notes without you filing them.
• Markdown Shell Extensions and Editor is open source (Apache-2.0), and SumizAI is not. If reading the source is what decides it for you, that is a real argument for Markdown Shell Extensions and Editor. The guarantee SumizAI offers instead is structural rather than legal: the notes are Markdown files in a folder you chose, so they open in any editor whether or not the application is running.
• Both keep Markdown, which makes moving between them mostly a matter of copying files. In SumizAI a vault is a directory holding base.md — a generated table of contents — and a notes/ folder with one .md file per note.
• AlternativeTo lists no mobile version of Markdown Shell Extensions and Editor. SumizAI runs on macOS, Windows, iOS and Android.
• Both are run from the EU: SumizAI's operator is registered in Poland and the servers are in Germany.

Which one to pick