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JSON Prism is a free browser-based JSON editor for developers working with API responses, configs, test fixtures, and generated payloads. Paste JSON once, then move between formatter, validator, visual editor, tree view, diff, converter, debugger, and sharing tools without opening another tab.
No install. Runs in any browser.
No data upload. 100% local processing.
19 tools in one workspace.
Beautify minified API responses, normalize indentation, and make nested data easier to review.
Catch missing commas, broken strings, trailing commas, and invalid values before they reach an API.
Use the visual JSON editor to update fields, booleans, arrays, and objects without hand-editing syntax.
Diff two payloads structurally so value changes stand out without noise from whitespace.
Turn JSON into CSV, YAML, XML, or other working formats from the same browser workspace.
Get clearer explanations for parser failures, invisible characters, LLM output, and rough pasted data.
Clean up minified or messy JSON with a fast browser-based formatter that keeps data local.
Check whether JSON is valid before it breaks a deployment, import, or API request.
Browse large JSON documents with expand, collapse, and search-friendly structure.
Edit JSON online without hand-editing commas, brackets, or quote marks.
Turn nested JSON into a visual map when raw text and trees are not enough.
Review payload changes faster with a dedicated JSON comparison workflow.
Reformat JSON into the output your workflow needs next.
Find and fix JSON syntax problems without guessing where the payload broke.
Clean permissive input so it becomes strict JSON ready for tooling and production systems.
Recover structured JSON from LLM output that is wrapped in commentary, markdown, or partial formatting.
Produce smaller payloads by selecting only the useful branches of a document.
Get high-level metrics that explain the structure and size of a JSON document.
Run a lightweight quality pass on JSON structure before it becomes technical debt.
Understand the likely token footprint of JSON before it reaches an LLM.
Create sample JSON faster when you need believable structures for testing and demos.
Share JSON safely through URL-based workflows that stay browser first.
Add context to payload reviews without switching into a separate notes app.
Group several JSON documents into one portable, review-friendly bundle.
A structured learning library for JSON fundamentals and advanced production topics.
JSON (JavaScript Object Notation) is a lightweight data format used by 70%+ of APIs. Learn what JSON is, why it exists, and when to use it.
Compare JSON, XML, and CSV with examples, strengths, limitations, and guidance on when to use each data format.
JSON supports exactly six data types. Learn strings, numbers, booleans, null, objects, and arrays with examples.
Master JSON syntax: double quotes for keys and strings, no trailing commas, no comments. Avoid common JSON mistakes.
Write your first JSON object with clear examples of keys, values, commas, data types, and common beginner mistakes.
Understand JSON objects, arrays, nesting, ordered lists, key-value pairs, and practical patterns for structured data.
Yes. JSON Prism is completely free. There is no sign-up, no subscription, and no usage limit. All core tools - formatter, validator, diff viewer, converter, debugger, and more - are available immediately.
No. All processing happens in your browser. Your JSON never leaves your machine unless you explicitly use the optional share link feature, which encodes your JSON in the URL fragment (never sent to a server) or stores it in Cloudflare KV for 30 days when you create a short link.
JSON Prism includes a formatter, validator, diff viewer, tree view, visual editor, flow view, converter (JSON ↔ CSV, XML, YAML), debugger, trimmer, token estimator, mock generator, AI JSON cleaner, structure analyzer, best practices checker, share links, notes, bundle viewer, and a learn-JSON mode.
Yes. JSON Prism is a Progressive Web App (PWA). After your first visit, the core workspace works offline. Install it from your browser's address bar to get a standalone app experience without any installation from an app store.
Formatting (beautifying) makes JSON readable by adding consistent indentation and line breaks - it does not change the data. Validation checks whether the JSON syntax is correct. JSON Prism runs both automatically and shows inline errors when your JSON is invalid.
Open the JSON Diff tool from the left sidebar or use the keyboard shortcut. Paste the first JSON in the left panel and the second in the right panel. Differences are highlighted immediately - structural diffs, not line-by-line text diffs, so reformatting does not show as a change.
Privacy by design
Every operation runs locally in your browser. No JSON is uploaded or stored by default. Short links are strictly opt-in and expire after 30 days.