devpreview.me
Developer files, readable
Only for Mac
Free
Mac
Opens JSON, XML, YAML, TOML, CSV, Markdown, CSS and JavaScript as something you can read — with a schema view, value tables and a map that contacts nobody.
Open a JSON API response, a YAML config, an XML feed or a minified
stylesheet in Safari and you get a wall of unformatted text. devpreview.me
turns it into something you can actually read — and then leaves every
other page alone.
Each of the eight formats it recognises gets the views that format
deserves:
• Rendered — syntax colours, collapsible nodes, and virtual scrolling
that stays fast on files with tens of thousands of lines
• Schema — the shape of the data instead of the data: which keys exist,
how often, of which type, with a click to copy any path
• Values — any array the schema cannot open further becomes a sortable
table, with a count of distinct values per column
• Map — coordinates found anywhere in the file, drawn on a world map
that ships inside the extension. No tiles are loaded, no map service
learns which region you are looking at. Click a point and its
coordinates are on your clipboard.
• Feed, Sitemap and API — RSS and Atom as a readable feed, sitemaps as a
list of addresses, OpenAPI as its operations grouped by path
CSS and JavaScript get the two views a stylesheet and a program need:
• A minified file is pulled apart again — line breaks and indentation
restored, syntax coloured, every bracket foldable. A click copies the
piece that belongs together: a CSS value alone, a property name with
its whole declaration, a selector with the entire rule. In JavaScript
a function's name copies the call as you would have to write it,
including the await; the word "function" in front of it copies the
whole function.
• Profile — what a stylesheet declares, and what only measuring can
answer. Colours split by what they do, custom properties resolved to
the value they end up being, every font size with its line heights,
weights, colours and measured contrast, the spacing and radius
scales, the breakpoints. Every number opens the selectors behind it.
• API — what a JavaScript file declares: its classes with their members,
its functions with what each one hands back — nothing, a value, a
promise, or itself — its module-level values, and every event it
listens for, with what runs and how the listener was registered.
A file is recognised by what it contains, not only by its extension, so
one served as plain text still opens in the view that suits it. And some
files are more than their syntax: XSD and WSDL open as the definitions
they declare, a plist as the settings it holds, an OPML file as the
outline it is. KML and GPX show their places and tracks, GeoJSON and
TopoJSON draw their features on the map. JSON Lines opens as the records
it streams, and TSV as the table it already was.
One search box searches whatever you are looking at, including the
schema and the raw source. CSV can be exported in a form Excel opens
correctly on a European system, with formula injection defused. What you
had open for a file comes back after a reload, for as long as Safari
runs.
Nothing leaves your machine. No account, no server, no analytics, no
telemetry. The only host devpreview.me contacts is the one whose file you
opened — the same request Safari was making anyway.
Ratings & Reviews
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The developer, Alpha Technology GmbH, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Alpha Technology GmbH
- Size
- 351.7 KB
- Category
- Developer Tools
- Compatibility
Requires macOS 26.5 or later.
- Mac
Requires macOS 26.5 or later.
- Mac
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Alpha Technology GmbH