OK JSON - Viewer & Formatter — Mac download

Developers, QA engineers, and anyone who regularly inspects API responses or configuration files will find OK JSON cuts through the noise. It replaces staring at a wall of text in a code editor with a purpose-built viewer that structures data on demand.

View

Open a raw JSON, JSON Lines, or NDJSON file and the app instantly presents a clean tree or text view. Quick Look integration means you can preview a file’s structure from Finder without launching a full editor.

Query

Use built-in jq support and saved JSONPath queries to extract exactly what you need from a large payload. Custom scripts based on JavaScriptCore let you process strings with your own logic.

Format

The version 3.0 text editor brings syntax highlighting and a redesigned interface that stays consistent across the viewer, History, and Quick Look. Drag a file onto the dock icon, run a saved jq filter, and copy out the formatted result.

15 MB file stays around 120–160 MB with live highlighting

OK JSON 3.0.1 keeps its footprint deliberately small. Opening a 15 MB NDJSON file on an M-series Mac settles memory use around 120–160 MB even with syntax highlighting active on every line. The tree viewer populates progressively — you see the top-level keys immediately, and deeper nodes expand without a loading spinner.

Stability is equally predictable. I have left it running across sleep/wake cycles with a dozen documents in History, each carrying saved jq filters, and not seen a single crash. The local database that powers History writes only when the window closes, so there is no constant disk chatter during active work.

A practical workflow: inspecting a broken API response

You receive a 2,400-line JSON payload from a QA ticket — an order object where the tax_lines array is coming back empty. Here is a clean path through OK JSON.

1. Copy the raw response body from your HTTP client.
2. Switch to OK JSON. It auto-detects the clipboard and displays the tree outline instantly.
3. Collapse all nodes, then expand orders → line_items to confirm item data is present.
4. Open the Query panel and paste a saved JSONPath expression: $.orders[*].tax_lines[?(@.rate==0.2)]. The result pane isolates only the 20% rate entries — empty across every item.
5. Switch to text view, spot the timestamp property near the payload footer, and note it predates the tax rate update by two hours.
6. Save the query result as a new snippet for the developer ticket and close the document. History records the file and your last query automatically.

The whole inspection takes under a minute. No terminal, no temporary files, no switching context to a code editor that tries to parse a malformed block.

• macOS 15 or later
• Apple Silicon or Intel 64-bit