You have a JSON blob, a JWT, a Markdown snippet or a Mermaid diagram, and you want to look at it. Right now that means opening a website you do not control and pasting your data into it.
CodePeek is the local answer to that habit. It lives in your menu bar, opens instantly, and renders what you paste — without a project, without a server, without a single byte leaving your Mac.
WHAT IT RENDERS
• Markdown — headings, lists, task lists, tables, code blocks, quotes, images • HTML & CSS — complete documents or bare fragments, wrapped for you • JSON — collapsible tree with type badges, formatted view, exact error positions • JWT — header and payload decoded, expiry in plain language, signature never trusted silently • Mermaid — flowcharts, sequence diagrams, Gantt charts • CSV & TSV — a real sortable table, delimiter detected automatically • SVG — see the graphic and its dimensions • React with JSX — compiled locally, with a console and readable errors • Diff — compare two texts line by line, with the changed words picked out
WHAT IT DECODES
• Base64 — encodes or decodes, standard and URL-safe, text or raw bytes • URLs — percent encoding both ways, plus the query string as a readable table • Timestamps — Unix time in any unit, as local time, UTC, ISO 8601 and "three days ago" • Checksums — MD5, SHA-1, SHA-256, SHA-384, SHA-512 • Cron — what the expression means in a sentence, and the next five times it runs
Leave it on Auto and CodePeek works out what you gave it.
AND CONVERTS BETWEEN THEM
JSON to CSV, JSON to YAML, CSV to JSON, Markdown to HTML — written straight back into the editor, and only offered when the content actually supports it.
BUILT TO STAY ON YOUR MACHINE
CodePeek is sandboxed. Preview content is served through a private URL scheme, never from the file system, so a page cannot read your files, your bundle, or the app's own data. A strict Content Security Policy blocks scripts, network requests and remote fonts in preview content by default. Images from the web load only if you switch that on yourself. Nothing is uploaded, nothing is logged, there is no account and no sync.
Your last ten snippets are kept in a plain JSON file inside the app's own container. That is the entire storage story.
DESIGNED FOR THE THIRTY SECONDS YOU ACTUALLY HAVE
• A global shortcut — yours to choose — opens CodePeek with whatever is on your clipboard, already rendered • Pin the snippets worth keeping and search the rest • Live preview with debouncing — no reload flicker while you type • An editor with line numbers, syntax highlighting, auto-indent and Find • Copy the rendered result as rich text, or export it as PNG, PDF or HTML • Drag a file onto the window, or watch a file and see edits appear as you save • Float the window above everything else while you work next to it • Light and dark preview, independent of your system appearance • Interface in English and German, switchable in Settings
WHAT IT IS NOT
CodePeek previews snippets. It is not an IDE and does not try to be. React mode runs a single file with no imports and no npm packages. Markdown covers the features listed above rather than every corner of CommonMark. If you need a build system, you already have one.
Requires macOS 14 or later.