How to open a JSON file (browser, editor, terminal, or online)
Every way to open a .json file: double-clicking in a browser, a text or code editor, the command line, and when an online JSON viewer is the faster option.
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Blog
Guides, notes and background reading.
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JSON cheat sheet: syntax, data types and operations on one page
A one-page JSON reference: syntax rules, all six data types, common parse and stringify operations, and worked examples. Read here or download as an image.
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JSON data types explained, with the edge cases that break parsers
The six value types JSON has, what each one cannot represent, and specific edge cases (big integers, trailing commas, duplicate keys) that catch people out.
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JSON Pointer vs JSONPath: what is the difference
JSON Pointer resolves one exact location and fails or succeeds. JSONPath is a query language that can match many values. Here is when to use each.
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Common JSON use cases: APIs, config files and data storage
Where JSON shows up: REST API payloads, application configuration, NoSQL documents, log pipelines and browser storage, and what each one expects from it.
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JSON vs XML: a practical comparison
Why JSON replaced XML as the default API format: less markup for the same data, and a more direct match to how programs model data.
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JSON vs YAML: differences, and when to use each
JSON and YAML can represent the same data. What differs is comments, readability, whitespace sensitivity and how forgiving each format is to write by hand.
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What is JSON? A beginner's guide to JavaScript Object Notation
What JSON actually is, why it replaced XML for most APIs, the six values it can hold, and where you will run into it day to day.
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How JWTs work: header, payload, signature
What the three dot separated parts of a JSON Web Token contain, why decoding one is not the same as verifying it, and what a decoder cannot tell you.
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How to convert JSON to JavaScript object literals and back
Using the JSON to JavaScript converter: what it accepts, what it refuses by name, why undefined is not silently turned into null, and how numbers stay exact.
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How to diff two JSON documents by what they mean, not how they look
Using the JSON diff tool to compare two documents by value instead of by text, and why reindenting a file should never show up as a change.
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How to Base64 encode JSON without breaking on accents or emoji
Using the JSON to Base64 converter, why the browser built-in function throws on non-ASCII text, and how the tool tells three kinds of decode failure apart.
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How to convert JSON to CSV without losing data
Using the JSON to CSV converter, why every field comes back a string on the way back, and what happens to nested values, null and commas inside a cell.
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How to convert JSON to NDJSON for logs and streams
Using the JSON to NDJSON converter, why blank lines are skipped, and how a broken line is reported by the number it actually has in your file.
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How to convert JSON to TypeScript interfaces
Using the JSON to TypeScript generator, how nested objects get named types, and why an optional mark on a key means something specific about your sample.
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How to convert JSON to XML with a stated mapping
Using the JSON to XML converter: choosing a root element, what happens to attributes, text and empty values, and why everything reads back as a string.
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How to convert JSON to YAML without the classic 01234 bug
Using the JSON to YAML converter, why a numeric-looking string has to be quoted, and which YAML features the reader supports and refuses by name.
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How to escape and unescape JSON strings correctly
Using the JSON escape and unescape tool, why the forward slash is left alone, and when to escape everything above ASCII.
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How to explore a large JSON document as a tree
Using the JSON viewer to walk a nested document, copy the JSONPath of any value, and why it stays responsive on documents other viewers freeze on.
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How to fix broken JSON automatically, and see every change
Using the JSON repair tool to turn a JavaScript object literal or a commented config into real JSON, with an itemised list of exactly what it changed.
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How to flatten JSON into paths and values, and back again
Using the JSON flattener for config files and spreadsheets, why a key holding the separator is refused, and how unflattening tells an index from a key.
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How to format JSON without losing precision
A walkthrough of the JSON formatter: indenting, minifying, reading the error gutter, and why some formatters quietly corrupt long numbers.
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How to generate a JSON Schema from a real sample
Using the JSON Schema generator: why a key missing from one record is marked optional, and how a schema built here is only as good as the sample.
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How to minify JSON and see exactly what it saved
Using the JSON minifier to strip whitespace without touching data, why format and minify are safe to switch between, and how much space it actually saves.
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How to sort JSON keys for a clean diff
Using the JSON key sorter, why arrays are never touched, and the option that fixes 10 sorting before 2 in an alphabetical comparison.
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How to URL encode JSON for a query string
Using the JSON URL encoder and decoder, when a space should be a plus sign instead of %20, and how the tool tells apart three different decode failures.
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How to use JSON Pointer, and what to do when it fails
A walkthrough of the JSON Pointer evaluator: the ~0 and ~1 escapes, the empty pointer, and reading a failed lookup that names the keys that actually exist.
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How to validate JSON and actually understand the error
How the JSON validator names the real mistake instead of the token it choked on, and why it warns about duplicate keys that most validators ignore.
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How to validate JSON against a JSON Schema
Using the JSON Schema validator to check a document against a schema and read every mismatch with its keyword and path, including how it handles a broken $ref.
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Common JSON syntax errors and how to fix them
The nine JSON errors that come up again and again, what the parser is actually complaining about in each case, and the exact edit that fixes it.
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How CuteJSON works, and why nothing you paste leaves your browser
What happens to a document you paste into this site, how to verify the no upload claim yourself in about thirty seconds, and where the tools stop.
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JSONPath cheat sheet, with worked examples
Every JSONPath selector worth knowing, each with a query you can run and the result it returns, plus three rules that explain most queries matching nothing.
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