Format Odyssey

FILE FORMAT GUIDE

JSON File (.JSON): Structure, Opening & Syntax

A JSON file represents structured data using objects, arrays and simple values. Open it in a JSON-aware editor to inspect the structure; parsing it does not explain what an application's fields mean. The name comes from JavaScript, but JSON is a separate interchange format, not a script to execute.

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Quick facts

Extension
.json
Format
JavaScript Object Notation
Category
data
MIME type
application/json
Standard / developer
IETF
Open with
Visual Studio Code

What is JSON?

JSON separates property names from values and keeps arrays ordered. Quoted strings, booleans, numbers and null have defined syntax. Duplicate object names can produce different parser results. Editor support for JSON with comments is a distinct mode: a file accepted in that mode is not necessarily valid standard JSON.

  • Exchange structured application data
  • Edit JSON configuration and schema-associated documents

How to open JSON

Visual Studio CodeDesktop editor

Open the file in VS Code and select JSON language mode if it is not detected. Inspect syntax diagnostics and format the document when helpful. Use JSON with Comments only when the consuming application explicitly accepts it; editor acceptance is not a guarantee that another parser accepts the file.

Technical details

Signature
No registered magic number
Encoding
UTF-8 for exchange between open systems
Container
Not applicable
Compression
Not inherent to the format

RFC 8259

Things to check

  • Duplicate object names reduce interoperability.
  • Comments are an editor extension, not standard JSON syntax.

Related formats

  • YAML

    Another representation of nested mappings and sequences; parser behavior and scalar types differ.

  • Extensible Markup Language

    An alternative structured interchange syntax based on elements rather than JSON values.

  • TOML

    A configuration-oriented alternative when explicit tables and typed values fit the consuming application.

Sources & review

Fact review: 2026-09-18. Unknown fields are not inferred from the file extension.