JSON Formatter

What JSON Is and Why Formatting Helps

JSON (JavaScript Object Notation) is one of the most common data formats used by APIs, configuration files, logs, and modern applications. It is lightweight, human-readable, and supported in nearly every programming language. The downside is that JSON is strict: one missing quote, one trailing comma, or one stray character can make it invalid.

A JSON formatter solves this by taking raw JSON and rewriting it with consistent indentation and line breaks. That makes it easier to read nested objects, spot missing fields, debug API responses, and share clean samples with teammates. When the tool also validates, you get immediate feedback on whether your JSON is syntactically correct.

Pretty Print vs Minify

Pretty printing adds whitespace and indentation so humans can scan structure quickly. Minifying removes extra whitespace to reduce size for transmission or storage. Both represent the same data, just in different “layouts.” This tool supports both by letting you choose indent style (2 spaces, 4 spaces, tabs, or 0 for minified output).

When debugging, pretty print is usually best. When embedding JSON in a URL, query parameter, or storage field with tight limits, minifying can help. The Minify button is a quick way to compress your JSON while keeping it valid.

Validation and Common JSON Errors

Strict JSON rules are a frequent source of frustration. Some of the most common causes of invalid JSON are:

• Trailing commas after the last item in an object or array
• Using single quotes instead of double quotes
• Unquoted keys (valid in JavaScript, invalid in JSON)
• Comments (JSON does not support them)
• Unescaped characters inside strings, such as an unescaped newline
• Extra text before or after the JSON document

This formatter can optionally strip common comment styles and remove trailing commas before parsing. That is useful when you copy JSONC-like config files or relaxed JSON snippets from tooling that isn’t strict. For production APIs, keep strict parsing on so you catch issues early.

Sorting Keys and “Deterministic” JSON

Sorting keys is a practical feature when you want stable output. Object property order is usually not meaningful for JSON semantics, but stable ordering makes it easier to compare payloads, review changes in version control, and create repeatable diffs. Turning on “Sort Object Keys” rewrites objects in alphabetical order.

If you are comparing API responses, sorting keys before diff is often the difference between a noisy diff and a clean diff. It doesn’t change your data, but it can dramatically improve readability.

Why JSON Lines Exists (JSONL)

JSON Lines (also called JSONL or NDJSON) stores one JSON object per line. It is widely used for logs and large datasets because you can stream and process records incrementally without loading one giant array into memory. Many data tools and pipelines prefer JSONL for this reason.

The Convert tab supports converting an array of objects into JSONL and converting JSONL back into a JSON array. That makes it easy to go from API exports (often arrays) to processing pipelines (often line-based) and back again.

Extracting Data with JSONPath

JSONPath is a query language for JSON, similar in spirit to XPath for XML. It lets you pull out values without manually scanning deep nesting. For example, you might want all IDs from an array of objects, or you might want a single nested field from a complex API response.

This tool includes a practical JSONPath runner. You paste the JSON, enter a JSONPath expression, and choose whether you want returned values, returned paths, or both. This helps when you are debugging responses, writing parsers, or building transformation rules.

Comparing Two JSON Documents with Diff

When you compare two JSON documents, raw diffs can be misleading because whitespace and key ordering create noise. The Diff tab normalizes JSON first (with chosen indentation) and can sort keys before running a line-based comparison. You can view the result as a unified diff or a side-by-side styled output.

The diff output highlights added lines, removed lines, and unchanged context lines. That makes it easier to answer questions like “What exactly changed in this API response?” or “Did a deployment alter a config value?” without manually searching.

Privacy and Safety Notes

JSON often contains sensitive information: access tokens, API keys, customer data, addresses, or internal identifiers. This tool runs fully in your browser, so nothing is uploaded or stored. Still, you should be careful when sharing screenshots or pasting output into public channels.

If you are formatting secrets, it’s best to redact them before sharing. In team environments, treat any exported JSON or diff output as potentially sensitive.

How to Use This JSON Formatter Efficiently

A simple workflow covers most needs:

• Paste JSON into the Format tab.
• Turn on comment stripping or trailing comma cleanup if you pasted relaxed JSON.
• Click Format to pretty print and validate.
• Use Minify when you need compact output.
• Use JSONPath when you need a specific field or set of values.
• Use Diff when comparing versions, responses, or environments.

If you need stable comparisons, enable “Sort Object Keys” and keep indentation consistent. That produces the cleanest diffs for review.