Free online JSON tools
A small collection of JSON utilities for developers, tech writers, and anyone working with APIs. Everything runs locally in your browser, so you can safely paste production data without worrying about where it ends up.
16 tools available
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JSON Prettifier
Format, minify, and validate JSON in your browser. Fast, free, private — your data never leaves your device.
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YAML to JSON
Paste YAML, get JSON. Anchors and aliases resolved, multi-document streams supported. Runs in your browser — no upload.
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JSON to YAML
Paste JSON, get clean YAML 1.2 with consistent indentation. Runs entirely in your browser — no upload, no signup.
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CSV to JSON
Paste a CSV (or TSV), get a JSON array of objects. Auto-detects headers, types numbers and booleans, runs locally — no upload.
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JSON to CSV
Paste a JSON array of objects, get a CSV with proper quoting. Header row from object keys, runs locally in your browser.
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XML to JSON
Paste XML, get JSON. Attributes preserved with @_ prefix, runs entirely in your browser — no upload, no signup.
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JSON to XML
Paste JSON, get formatted XML. Keys with @_ prefix become attributes, runs entirely in your browser — no upload.
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TOML to JSON
Paste TOML, get JSON. Tables become objects, arrays of tables become arrays. Runs in your browser — no upload.
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JSON to TOML
Paste JSON (top-level object), get TOML. Strict spec compliance, runs entirely in your browser — no upload.
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YAML Formatter
Paste YAML, get it formatted with consistent indentation and validated. YAML 1.2 strict mode. Runs in your browser — no upload.
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XML Formatter
Paste XML, get it formatted with proper indentation and validated. Handles attributes and namespaces. Runs in your browser — no upload.
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TOML Formatter
Paste TOML, get it formatted in canonical order and validated against TOML 1.0. Runs in your browser — no upload.
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JSON to Struct
Paste JSON, get an idiomatic struct in TypeScript, Go, Rust, Kotlin, Java, C#, or Python. Powered by quicktype, runs in your browser.
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CSV Viewer
Paste or drop a CSV, view it as a sortable table. Headers auto-detected, columns clickable to sort. Runs in your browser — no upload.
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XLSX to CSV
Drop an XLSX file and export each sheet as CSV. Powered by SheetJS, runs entirely in your browser — no upload, no signup.
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CSV to Markdown
Paste a CSV, get a GitHub-flavored Markdown table. Headers auto-detected, alignment configurable. Runs in your browser.
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Why use these json tools?
Safe for production data
Because JSON never leaves your browser, you can paste API responses, config files, or payloads that might contain secrets without risking exposure to a third-party service.
Instant feedback
No network round-trip. Paste JSON, click Prettify, see the result. Invalid JSON gets a clear error message with the parse position.
No clutter
No ads stuffed inside the textarea. No paywalls, no feature gates, no "sign up to continue." Just a textarea and a handful of buttons that do what they say.
Common use cases
- Formatting an API response pasted from curl or a browser network tab
- Minifying a config file before embedding it in a URL or environment variable
- Quickly checking whether a string is valid JSON before using it
- Cleaning up LLM-generated JSON that has inconsistent indentation
Frequently asked questions
Does this tool store my JSON anywhere?
No. All parsing and formatting happen in your browser using the built-in JSON parser. Nothing is uploaded or logged.
What are prettify, minify, and validate?
Prettify re-formats JSON with indentation so it is easy to read. Minify strips all whitespace to make the output as small as possible. Validate checks whether the input is well-formed JSON and reports any syntax error.
Can I format JSON that contains comments?
Strict JSON does not allow comments. If your input has them, remove or convert to a superset like JSON5 first — this tool uses the standard JSON parser.