Yes. JSONViewer is completely free and open source. There is no cost, no account, and no subscription.

Does JSONViewer work offline?

Yes. JSONViewer runs fully offline and processes everything locally. Your JSON data never leaves your machine.

How do I extract a field from a JSON array?

Use the JSONPath-subset extractor. For example, $[*].id returns the id of every element in the top-level array, and $.users[*].email returns every user email. Results open in a separate window with Copy and Download buttons.

What macOS versions are supported?

JSONViewer supports macOS 13 or later on Apple Silicon (arm64). It is a native SwiftUI application.

Is the gzip output compatible with command-line gzip?

Yes. The Gzip&BASE64Encode and BASE64Decode&Ungzip transforms use real gzip, so the output is interoperable with the system gzip and gunzip command-line tools.

How do I open an unsigned app on macOS?

The release builds are unsigned arm64 binaries. On first launch, right-click (or Control-click) the app in Finder and choose Open, then confirm in the dialog. After that it opens normally.

Native · Free · Open source

The JSON tool for macOS that never touches the network.

Format, validate, explore and transform JSON in a fast, private, native SwiftUI window. Free and open source, built for Apple Silicon.

Download for macOS View on GitHub

macOS 13+ · Apple Silicon · v1.1.0 · unsigned (right-click → Open)

What it does

Everything you need for JSON, nothing you don't.

Format & minify

Beautify with 2-space, 4-space or Tab indentation, or minify to a single compact line.

Validate with line:column

Catch syntax errors instantly with precise line and column reporting — no guessing.

Syntax highlight & tree

Read JSON with colored syntax highlighting, or navigate nested data in a collapsible tree.

JSONPath extraction

Pull values with a JSONPath subset like $[*].id or $.users[*].email — results open with Copy & Download.

9 transforms

One-click JSON escape, Base64, URL encode and real gzip — each with line-numbered output.

JSON Compare

Diff two JSON documents side by side: a summary of added, removed and changed counts plus a color-coded tree showing each change as old → new.

Offline & private

Runs entirely on your Mac. Your data never leaves the machine — no servers, no telemetry.

The interface

A real native window, not a browser tab.

JSONViewer — sample.json

1{
2  "app": "JSONViewer",
3  "version": 1.1,
4  "offline": true,
5  "users": [
6    { "id": 1, "email": "a@b.dev" },
7    { "id": 2, "email": "c@d.dev" }
8  ]
9}

JSON Escape JSON Unescape BASE64 Encode BASE64 Decode URL Escape URL Unescape Gzip&BASE64Encode BASE64Decode&Ungzip String UnEscape

Try it here

Format JSON right in your browser.

A taste of the app — runs entirely in your browser, nothing is uploaded. The desktop app does much more.

Input JSON

Indent

Output

JSONPath subset

Extract exactly the values you need.

Type a path; matching values open in a separate window with Copy and Download.

$[*].idThe id of every element in a top-level array

$.users[*].emailEvery email under the users array

$.a.b[*].xField x across a nested array

[index]A single array element by position

['key']A property by quoted key name

FAQ

Questions, answered.

Is JSONViewer free?: Yes. JSONViewer is completely free and open source. There is no cost, no account, and no subscription.
Does JSONViewer work offline?: Yes. JSONViewer runs fully offline and processes everything locally. Your JSON data never leaves your machine.
How do I extract a field from a JSON array?: Use the JSONPath-subset extractor. For example, $[*].id returns the id of every element in the top-level array, and $.users[*].email returns every user email. Results open in a separate window with Copy and Download buttons.
What macOS versions are supported?: JSONViewer supports macOS 13 or later on Apple Silicon (arm64). It is a native SwiftUI application.
Is the gzip output compatible with command-line gzip?: Yes. The Gzip&BASE64Encode and BASE64Decode&Ungzip transforms use real gzip, so the output is interoperable with the system gzip and gunzip command-line tools.
How do I open an unsigned app on macOS?: The release builds are unsigned arm64 binaries. On first launch, right-click (or Control-click) the app in Finder and choose Open, then confirm in the dialog. After that it opens normally.

Get JSONViewer for macOS.

Free and open source. Download the latest release — DMG or ZIP — for Apple Silicon.

Download latest release View source on GitHub

JSONViewer-1.1.0.dmg / JSONViewer-1.1.0.zip · arm64 · unsigned (right-click → Open)