SumizAI vs PeekMark

What PeekMark is

What PeekMark is

PeekMark is a native, fully local Markdown viewer and workspace for macOS, built for users who want to quickly glance at their notes without launching a heavyweight editor. The app integrates with the system's Finder Quick Look, so a single tap of the space bar on a .md file in Finder shows a fully rendered note — with Mermaid diagram and math rendering support — without opening a separate program. That approach puts PeekMark somewhere between a plain file previewer and a full-fledged notes app.

Key features

Finder Quick Look integration is the feature that sets PeekMark apart from other Markdown viewers — it lets you glance at a note's content directly from the file system, without switching between apps. Mermaid diagram rendering supports visualizing flows, charts, and structures right inside the note's text, which is especially useful for developers documenting system architecture. Math notation support lets researchers and students display formulas without converting them to images. Optional workspaces let you group related files into larger collections once single-file previewing stops being enough. Full-text search searches the content of every note in a workspace at once, and backlinks show which other notes reference the current one, building a web of connections similar to a knowledge graph. A built-in knowledge graph visualizes these connections as an interactive map of nodes and links.

Who it's for

PeekMark appeals to people who work daily with a large number of Markdown files — developers documenting code, researchers keeping scientific notes with formulas, and anyone who values a fast content preview without waiting for a full editor to launch. Users committed to local file storage, without depending on a third-party cloud provider, will find a tool aligned with that philosophy.

Use cases

In practice, PeekMark works well when you need to quickly check the content of a technical note in Finder without interrupting work in another program. A developer browsing project documentation can hit the space bar once and see an architecture diagram rendered from Mermaid code. A researcher browsing a set of notes with equations can instantly verify a specific formula without opening a LaTeX editor. Someone organizing a large collection of Markdown notes can use the knowledge graph to see which topics connect to each other and where there are gaps in the collection.

Pricing and business model

PeekMark runs on a freemium model while also being open source under the AGPL-3.0 license — basic preview functionality is free, and extended features like workspaces or the knowledge graph may require a paid tier. The open source code lets a community of developers audit the app and submit fixes, a rarity among native macOS tools.

Limitations and what to watch for

PeekMark is available on macOS only, so Windows and Linux users have no access to it. The app focuses on preview and light editing rather than advanced formatting or the extensive editorial features found in full-fledged note apps — this is a tool for quick glances, not for intensively writing long documents.

AI notes and quick previewing

PeekMark has no built-in AI model integration, but its strength lies precisely in instant previewing — if you save an ai notes entry from a conversation with an assistant as a .md file in your file system, PeekMark lets you review it with one tap of the space bar, no editor required. For people accumulating many such ai notes entries from different AI sessions, PeekMark's knowledge graph can help surface connections between them, as long as the notes link to each other through standard Markdown references.

What's worth checking before choosing

Before fully relying on PeekMark, check whether the features that matter to you — workspaces or the knowledge graph, say — are available in the free tier or require a paid plan, and make sure you're on macOS, since PeekMark doesn't support other platforms.

Bottom line

PeekMark is a fast, native way to browse a collection of Markdown files on macOS with advanced diagram and formula rendering. Anyone who wants ai notes from AI conversations to land there automatically as ready files instead of being manually saved should consider a tool built around that specific workflow.

Speed as a design philosophy

PeekMark was designed around the assumption that the most common interaction with a note isn't editing it, but quickly checking its content — hence the emphasis on Quick Look integration rather than building yet another full-fledged text editor. That philosophy means the app launches and renders notes almost instantly, without the delays typical of heavier tools that load an entire interface every time a file opens.

The local nature of the data

Because PeekMark works directly on files on disk, with no sync cloud of its own, full responsibility for backup and cross-device sync rests with the user and whatever tool they choose — iCloud Drive or Dropbox, for instance. For people who value full control over where their files physically live, that's an advantage rather than a limitation.

A place in the daily workflow

Many users run PeekMark alongside their main Markdown editor rather than instead of it — writing and editing in one program, while opening PeekMark purely to quickly check the content of files they don't want to open in a full editor at that moment. That split of roles — a heavier editor for writing, PeekMark for browsing — saves time when working with dozens or hundreds of files a day. Over time that habit becomes a natural part of the workday, saving dozens of small app switches that seem trivial individually but add up to real, measurable distraction.

Comparison with SumizAI

PeekMark and SumizAI agree on format — Markdown files, stored locally. They differ in content source: PeekMark is a viewer for existing files the user already has and writes themselves, while SumizAI generates ai notes directly from a conversation with an AI model, turning answers worth keeping into ready files without manual saving. Anyone who already has a large collection of Markdown notes and wants fast previewing with a knowledge graph will pick PeekMark; anyone who wants ai notes from AI conversations to be created automatically will find SumizAI the better-fitting tool.

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 PeekMark 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.
• PeekMark is open source (AGPL-3.0), and SumizAI is not. If reading the source is what decides it for you, that is a real argument for PeekMark. 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.
• PeekMark is freemium: there is a free tier and a paid one, and the line between them is the thing to read before committing. SumizAI has one plan at a dollar a month, so there is no feature held back for a higher tier — and an unpaid account still opens and exports every vault it already has.
• 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.
• PeekMark is described in terms of linking notes together. SumizAI links them too, but deliberately without a syntax of its own: a link is an ordinary Markdown link, [Title](file-name.md), and the model may only point at a file that actually exists. There are no wiki-style [[…]] links to lose on export.
• AlternativeTo lists no mobile version of PeekMark. SumizAI runs on macOS, Windows, iOS and Android.
• Both export. SumizAI exports a whole vault as a PDF — summary or full detail — or as a .pptx deck in table-of-contents order, with fifteen slide themes.

Which one to pick