JSON Tools
Format, validate, compare and convert JSON, YAML, XML, CSV and TOML — every operation runs locally in your browser.
8 tools
JSON tools cover the whole lifecycle of a structured-data file: making an unreadable single-line payload readable, proving that it is valid, comparing two versions to see exactly what changed, and moving the same data between JSON and the formats that surround it — YAML for configuration, TOML for build files, XML for legacy APIs, CSV for spreadsheets.
This space is reserved for a sponsor. Every tool on this site stays free and runs locally in your browser.
JSON Formatter
Paste JSON to pretty-print it with consistent indentation, minify it to one line, or find the exact line and column of a syntax error. Runs locally.
JSON Diff
Compare two JSON documents and see every added, removed and changed value, with the JSON path of each difference and a one-click copy.
JSON to CSV
Convert JSON to CSV with a documented rule for flattening nested objects and arrays, plus a round-trip check that shows what the reverse conversion loses.
JSON to YAML
Convert JSON to YAML and YAML to JSON in your browser, with a clear note on what the round trip loses: comments, anchors, multiple documents and key order.
JSON Schema Validator
Validate a JSON document against a JSON Schema and get every error with its exact path, including failures nested inside objects and array items. Runs locally.
JSON to XML
Convert JSON to XML and XML to JSON with the array mapping rules spelled out, so the output matches what your downstream consumer expects.
JSONPath Tester
Run a JSONPath expression against your own JSON and get every match together with the path that reached it. Filter, slice and search without writing code.
JSON to TOML Converter
Convert JSON to TOML and TOML to JSON, with a clear choice for how null values are handled, since TOML has no null. Runs locally.
About JSON Tools
Everything on these pages runs inside your browser tab. That matters more for JSON than for most categories, because the text people paste into a formatter is rarely a toy sample: it is an API response holding customer records, a service-account key, a production config with credentials in it, or an error payload captured from a live system. A tool that uploads that text to a server turns a formatting job into a data-sharing decision.
The tools split along two axes: whether they inspect the data (validate, compare) or reshape it (format, minify, convert), and whether the output is meant for a human or for another program. If you are unsure where to start, format first — a pretty-printed document is far easier to diagnose than a single 40 KB line.
Frequently asked questions
Does the formatter send my JSON to a server?
No. Parsing, pretty-printing, validation and conversion all run as JavaScript in your browser. There is no upload and no backend endpoint involved. You can confirm it in a few seconds: open a tool, then disconnect your network and use it again. Every JSON, YAML, CSV, TOML and XML tool keeps working, because nothing ever leaves the tab.
Why does my JSON fail to validate, and how do I find the problem?
The usual causes, in rough order of frequency, are a trailing comma before a closing brace or bracket, a missing comma between members, single quotes instead of double quotes, an unquoted key, and a comment left by someone used to writing JavaScript. The validator reports the byte offset together with the line and column, so read the position it names and then look at the character immediately before it — the parser stops one token after the real mistake, not at it.
What is the difference between JSON and YAML?
They describe the same data model — maps, sequences and scalar values — using different syntax. YAML is built for humans writing configuration by hand: indentation instead of braces, comments allowed, multi-line strings without escape sequences. JSON is built for machines: unambiguous, minimal, trivially parseable. The practical consequence is that nearly all YAML can be expressed as JSON but not the reverse, because JSON has no comments and no anchors. The converters go both ways so a config can move between the two without being retyped.
Can I convert CSV to JSON with nested objects?
Yes, within limits. A flat CSV maps cleanly onto an array of objects, with the header row supplying the keys. Nesting needs a convention for expressing structure in a flat file — dotted column names such as user.address.city, or a repeated prefix grouping related columns. The converter supports the dotted-path convention and infers types (numbers, booleans, null) instead of quoting everything as a string. Genuinely irregular CSV — merged cells, multi-row headers, several tables in one file — has to be cleaned first, because no converter can guess which layout was intended.
Is there a size limit on what I can paste?
The practical limit is your device's memory rather than a fixed number, because the document is held in the tab instead of being posted to a server. Files in the low tens of megabytes format in about a second on a laptop. Very large inputs slow down syntax highlighting before they slow down the parser, so if a large file feels sticky, switch to minified view and the rendering cost drops sharply.
Related categories
Text Tools
Word and character counting, manuscript fee estimates and other text utilities that run entirely in your browser.
Encoding & Escaping
Escape, unescape and encode text and structured data — JSON string escaping, Base64 and character encoding, all running locally in your browser.
Converters
Currency conversion across 162 currencies with the mid-market rate, the inverse rate and the quote source shown for every figure.
This space is reserved for a sponsor. Every tool on this site stays free and runs locally in your browser.