# A fast JSON viewer in Finder, for JSONC and JSON Lines too

> Preview JSON in Finder with Quick Look: a Tree view and the raw text, fast even for large files, plus JSON with comments and JSON Lines logs.

Press Space on a `.json` file and Gander opens it at once, even a large one, with a **Tree** of keys and values and the **Raw** text. Files with comments and trailing commas, such as `tsconfig.json` or `.jsonc`, work as well, and JSON Lines logs show one record per line.

![forecast.json in the Tree view: the city, the country and the current conditions as nested keys and values.](https://ganderfinder.com/img/features/json-tree-2x.webp)
![api-requests.jsonl with record 6 expanded as indented JSON, showing an upstream timeout error.](https://ganderfinder.com/img/features/jsonl-open-2x.webp)

## How to do it

1. Install Gander from the Mac App Store and open it once.
2. Select a `.json`, `.jsonc`, `.jsonl` or `.ndjson` file in Finder and press Space.
3. Switch between **Tree** and **Raw**. In JSON Lines, click a line number to expand that record.

## Tree and Raw

Tree shows the structure as nested keys and values. Raw keeps the file exactly as written, comments included, with line numbers one click away. The copy button copies whichever view is on screen, and files up to 1 MB open whole.

## JSON with comments

Gander reads strict JSON first and, if that fails, reads the file again with JSON5 rules. So comments and trailing commas, in `.jsonc` files and in `.json` files such as `tsconfig.json`, still get a Tree. A broken file still opens, as highlighted text.

## JSON Lines and NDJSON logs

`.jsonl` and `.ndjson` files show one record per line, so a log with thousands of entries opens in a moment. Click a record’s line number to expand it as indented JSON, in the file’s own key order, and click again to fold it. `package.json` gets its own overview of the name, version, scripts and dependencies.

## Questions

### How large a JSON file can Gander open?

Files up to 1 MB open whole, in about a tenth of a second. A longer file shows its first 1 MB, with a note saying so.

### Does Gander change my JSON?

No. Raw shows the file exactly as written, and Gander never writes to it.

### Do JSON files get Finder thumbnails?

Yes. JSON, JSONC and JSON Lines files get thumbnails of their coloured text in Finder’s icon and gallery views.

## More guides

- [Preview Markdown in Finder, rendered the way GitHub shows it](https://ganderfinder.com/markdown-quick-look)
- [View Mermaid diagrams on your Mac without a browser](https://ganderfinder.com/mermaid-viewer)
- [Turn Markdown into a PDF or a Word document, right from Finder](https://ganderfinder.com/markdown-to-pdf-word)
- [Convert CSV to Excel on your Mac, straight from Finder](https://ganderfinder.com/csv-to-excel)
- [Read Jupyter notebooks on your Mac without starting Jupyter](https://ganderfinder.com/jupyter-notebook-viewer)
- [Look inside an SQLite database from Finder](https://ganderfinder.com/sqlite-viewer)
- [Read any SQL query neatly laid out, without changing the file](https://ganderfinder.com/sql-formatter)
- [Open log files at the newest line, with errors in red](https://ganderfinder.com/log-viewer)
- [Check a .env file without putting secrets on screen](https://ganderfinder.com/env-file-viewer)

Gander is free on the Mac App Store, with no in-app purchases, no subscription and no account, and nothing you preview leaves your Mac. https://apps.apple.com/app/id6817038818

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