How to Read a JSON File: A Practical Guide

Reading a JSON file means looking at the data it contains, either directly as text or through a program that turns it into usable values. JSON (JavaScript Object Notation) is a common format for settings, exports, API responses, and other structured information. You do not need JavaScript to read it: many languages and text editors support JSON.

Before opening a file, make sure you know where it came from and whether it contains sensitive information. A JSON file is not normally an executable program, but data can still contain untrusted text or links. Do not run commands or paste private data into an online viewer unless you trust the service.

What You’ll Need

To inspect it: the JSON file and a plain-text editor, such as Notepad, TextEdit in plain-text mode, or a code editor.
To read it in a program: a programming language with a JSON parser, such as Python, JavaScript, Java, or another language you use.
Optional: a JSON-aware editor or local formatter to make long or compact files easier to read.

Step-by-Step

Find the file. Locate the file in your downloads, project folder, or the location where an app exported it. JSON files commonly end in .json, though a file can contain JSON without that extension. If you received it from someone else, confirm it is the file you intended to open.
Choose how to read it. For a quick look, use a text editor. On a computer, right-click the file and select an option such as Open with, then choose your editor. Menu names vary by operating system and version. Avoid opening it in a word processor if possible; rich-text formatting can obscure punctuation or alter the content when saved.
Check the opening characters. JSON usually begins with { for an object or [ for an array. Objects contain named properties, such as "name": "Ava"; arrays contain ordered values inside square brackets. A file can also hold a single string, number, Boolean value, or null.
Follow the structure. Read from the outside inward. Curly braces group properties; square brackets group list items. A colon separates a property name from its value, and commas separate neighboring properties or items. Indentation and line breaks make the structure clearer but are optional, so a one-line file can still be valid JSON.
Recognize the value types. Text appears in double quotes, numbers do not, and the exact lowercase words true, false, and null have special meanings. Objects and arrays can be nested inside other objects or arrays. For example, an address may be an object nested under a person’s details.
Load it with a parser when needed. In Python, open the file as UTF-8 text and pass the file handle to json.load() from the built-in json module. In JavaScript, read the file as text using the environment’s file-reading method, then pass the text to JSON.parse(). File-reading methods differ between browsers, servers, and other runtimes; use the one appropriate to your environment.
Use the parsed data. After parsing, access an object property by its key or select an array element by its position, using the syntax of your language. Check whether the value is actually present and has the expected type before using it. A property might be missing, contain null, or hold a list instead of a single value.
Validate and preserve the original. If the file will be edited or processed, validate its syntax with your editor or parser, then save a copy before making changes. A parser confirms that the text follows JSON syntax, not that every value is correct for your particular application.

Common Mistakes

Using single quotes: JSON strings and property names require double quotes. {'name': 'Ava'} is not valid JSON; {"name": "Ava"} is.
Leaving a trailing comma: The final item in an object or array must not have a comma after it. Some programming languages allow this in their own syntax, but standard JSON does not.
Confusing JSON with a programming-language object: JSON is a data format. Text such as comments, variables, and expressions is not allowed in standard JSON, even if a language’s object syntax permits them.
Assuming numbers are text: "42" is a string, while 42 is a number. Treating one as the other can cause comparisons or calculations to behave unexpectedly.
Ignoring nesting: A key may be several levels inside an object, or a value may be an array of objects. Check the surrounding braces and brackets before assuming where a value belongs.
Trusting the contents because parsing worked: Valid syntax does not guarantee accurate, safe, or trustworthy information. Treat external data cautiously and do not use it as instructions to run.

Tips

Use a JSON-aware editor to highlight braces, show indentation, and flag syntax errors. Formatting changes how the file looks, not what its data means.
For a compact file, use a formatter or “pretty print” feature. For a large file, search for a known key rather than reading every line, and check its context so you know which nested object it belongs to.
When writing code, handle errors from both file access and parsing. A missing file, invalid text encoding, or malformed JSON can prevent the data from loading.
Keep the original file unchanged when experimenting. Work on a copy, especially if the file is an app configuration or an export you may need later.
Use UTF-8 when reading or writing JSON unless the file’s source documents another encoding. If text appears garbled, inspect the encoding rather than replacing characters at random.

Troubleshooting

The file looks like one long line: That can be normal. Use an editor’s formatting feature or a local JSON formatter to add indentation. Do not add commas or braces just to make it look organized.

The editor shows strange characters: Confirm you opened the correct file and check its text encoding, commonly UTF-8. If it is not actually a text file, an editor may display unreadable symbols; verify its source and extension.

The parser reports a syntax error: Read the error location, then inspect nearby quotes, commas, colons, braces, and brackets. Errors are often reported slightly after the character that caused them. Check that strings use double quotes, special values are lowercase, and no comments or trailing commas are present.

The program says a key is missing: Check the exact spelling and capitalization, then inspect the object’s nesting. JSON keys are text, and "Name" is different from "name". Also check whether the property is optional or represented by null.

The file opens but the data is unexpected: Confirm whether the top-level value is an object or an array, and inspect the actual types. An API response may also wrap the information in an outer property such as data or results.

Frequently Asked Questions

Can I read a JSON file without coding?

Yes. Open it in a text editor or a JSON-aware viewer to inspect its contents. You only need code if you want to load, search, or process the values automatically.

Is a JSON file the same as a JavaScript file?

No. JSON is a text format for data, while JavaScript is a programming language. JavaScript can parse JSON, but JSON does not contain JavaScript comments, functions, or variables.

Can I open JSON in Excel?

Some spreadsheet programs can import JSON, but the steps and support vary by version. For a quick inspection, a text editor is simpler; for a large dataset, use the spreadsheet’s documented import feature and check how nested data is represented.

Why does my JSON file fail to parse?

Common causes include single quotes, a missing comma, an extra trailing comma, unescaped quotation marks, or mismatched braces. Check the parser’s reported location and inspect the surrounding text.

Is it safe to open a JSON file?

Viewing it as text is generally different from running a program, but the file can contain misleading links or sensitive data. Do not trust instructions inside it, and avoid uploading private contents to an untrusted online tool.

Does JSON have to be formatted across multiple lines?

No. Whitespace and indentation are optional outside strings, so valid JSON can be compacted onto one line. A formatter can make it easier to read without changing the data.

Further reading: Python Software Foundation. Details can change, so check the official page for anything that matters to you. Spotted a mistake? Tell us. How we write an answer.