{ }JSONFmt/docs
Formatter

Documentation

JSONFmt reference.

The free, privacy-first JSON and YAML toolkit. Everything runs locally — no accounts, no uploads, no cost.

Getting StartedSupported FormatsFeaturesUpload Guide

Getting Started

No installation, no sign-up, no configuration. Open the formatter and start working immediately.

  1. 1

    Open the Formatter

    Navigate to /formatter or click "Open Formatter" from the home page.

  2. 2

    Paste or Upload

    Paste JSON/YAML into the left panel, or drag-and-drop a file. Format is auto-detected.

  3. 3

    Format

    Output appears automatically. Press Ctrl+Enter to re-format with current settings.

  4. 4

    Export

    Click Copy or use the Download dropdown to save as .json, .yaml, or .txt.

Supported Formats

JSON.json

Standard JSON — objects, arrays, strings, numbers, booleans, null.

JSONC.jsonc

JSON with Comments (// and /* */ syntax). Used in VS Code configs.

YAML.yaml, .yml

YAML 1.2 — Kubernetes manifests, Docker Compose, GitHub Actions workflows.

Features

Format / Beautify

Indents and pretty-prints. Configure indent (2 or 4 spaces) and key sorting in Settings.

Minify

Strips all whitespace. Shows before/after sizes and % saved.

Convert JSON ↔ YAML

Flip between formats instantly. Types and nesting preserved.

Validate

Syntax errors surface with line + column numbers, explanations, and fix suggestions.

Tree Viewer

Collapsible interactive tree. Search keys, copy paths, inspect value types.

JSON Schema Generator

Auto-derives a draft-07 JSON Schema from any data structure.

TypeScript Generator

Generates TypeScript interfaces or type aliases directly from your data.

Compare Mode

Side-by-side diff with path-annotated added, removed, and changed values.

Multi-tab Workspace

Open multiple files in tabs. Each tab independently tracks format and content.

Upload Guide

Three ways to load a file:

  1. Drag & drop — Drag any .json, .yaml, .yml, or .jsonc file onto the formatter window.
  2. File picker — Click the upload icon in the tab bar or press Ctrl+O.
  3. Paste — Paste raw text directly into the input panel. Format is auto-detected.

Multiple files open as separate tabs, each with its own format detection and modified state.

Privacy note

Files are read by the browser's FileReader API and stay in memory. Nothing is ever transmitted to a server.

Keyboard Shortcuts

Open Command PaletteCtrl + K
Format inputCtrl + Enter
Minify inputCtrl + Shift + M
Copy output to clipboardCtrl + Shift + C
Toggle the JSONPath query barCtrl + Shift + F
Copy a share link for the current documentCtrl + Shift + S
Open file upload dialogCtrl + O
Toggle the shortcuts dialogCtrl + /
Indent (or outdent with Shift) in the editorTab
Close dialog / paletteEscape

Privacy

Your data never leaves your browser. There is no server to send it to.

Open tabs and settings are kept in this browser’s localStorage so a refresh does not lose your work. Clearing site data removes them.

Local Processing

All JSON parsing, formatting, minification, and conversion runs in your browser via standard JavaScript APIs.

No Server Uploads

File data is read via the FileReader API and stays in JavaScript memory. Nothing is transmitted.

No Accounts or Tracking

No authentication, no analytics, no tracking pixels or fingerprinting.

No Permanent Storage

File content is never written to localStorage. Only editor preferences (indent, font, theme) are persisted.

Session-only Data

When you close the tab, all data is cleared automatically.

FAQ

Is this tool free?

Yes. JSONFmt is completely free, forever. No subscriptions, no premium tier, no ads.

Do I need to create an account?

No. Open the formatter and start working. Zero friction.

Is my data sent to a server?

No. All processing happens entirely in your browser. Your data never leaves your machine.

How do share links work?

The document is encoded into the URL fragment (the part after #). Browsers never transmit a fragment to the server, so the data stays on the machines of whoever holds the link. Anyone with the link can read the document, so treat it like the data itself.

What file formats are supported?

Reading: JSON, JSONC, YAML, TOML, CSV, XML, INI and .env. Any of them can be converted to any of the others, subject to what the target format can express — CSV needs an array of flat objects, and INI/.env need an object at the top level.

Is my work saved between visits?

Open tabs and settings are kept in your browser localStorage so a refresh does not lose them. Clearing site data removes them; nothing is stored anywhere else.

How large can my files be?

There is no enforced limit. Very large files (100 MB+) may be slower depending on your device. Everything runs locally.

Can I use this offline?

Yes. Once the page is loaded, JSONFmt works fully offline. No network required.

What is JSONC?

JSONC is JSON with Comments — allows // and /* */ comments. Used in VS Code config files.

Ready to use it?

No setup required. Open the formatter and start working immediately.

Open Formatter No sign-up · No install · Free