JSON Generator/Formatter
Commercial use OK
380+ models
No watermark
No sign-up needed
Model:
+ GPT-5, Claude, Gemini
Format, validate, minify, diff, convert, or AI-generate JSON — all in one place. Client-side validate/format runs instantly in your browser with no network call. AI modes (generate from description, explain parse errors, convert to YAML/TOML/XML/CSV) cost ~100 tokens.
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Generate and format JSON with free AI. Create schemas, mock data, and more.
How to Use JSON Generator/Formatter
1
Enter your input
Type text, upload a file, or describe what you want. No account needed.
2
Click generate
Our AI processes your request in seconds using the best open-source models.
3
Download & share
Download, copy, or share your result. Free for personal and commercial use.
Use this tool via API
Automate this tool from your own code. OpenAI-compatible REST endpoint, Bearer-token auth, no extra SDK required. Token costs match the web interface.
curl -X POST https://api.free.ai/v1/chat/ \
-H "Authorization: Bearer sk-free-..." \
-H "Content-Type: application/json" \
-d '{"model": "qwen-coder", "messages": [{"role": "user", "content": "Write a Python function that reverses a string."}]}'JSON Generator/Formatter — FAQ
Paste JSON to format, validate, minify, or diff. Or describe a JSON structure ("user object with id, email, address.street, and roles array") and get back a sample. Or paste invalid JSON and get back the fixed version with a per-error explanation. Tree view, copy / download, and one-click conversion to YAML / TOML / XML / CSV.
JSONLint and JSONFormatter.org are free, ad-supported, and only validate / format. JSON Editor Online is excellent for editing but doesn't generate new JSON from descriptions. Free.ai combines all of those in one tool, no ads, plus AI-driven generation, error explanation in plain English, and conversion to other formats — all under the daily free token pool.
Format / validate / minify run client-side in your browser — instant, no network call, works offline. AI-driven generation, error explanation, and format conversion call the GPU and require a connection. The page caches the last result so refreshing won't lose your work mid-edit.
Yes — every parse error is annotated with the line / column, the actual character causing the problem, the most likely fix (extra trailing comma, unquoted key, single instead of double quotes, missing closing brace), and a corrected version you can copy. JSONLint just says "expecting comma at line 5"; Free.ai says "trailing comma after `roles`: [...]; remove it" with the fix highlighted.
Yes — one-click buttons convert to YAML, TOML, XML, CSV (when the structure is array-of-objects), and Markdown table (same constraint). For CSV / Markdown of nested data, the converter flattens with dot-notation columns by default (`address.street`) — toggle to JSONPath if needed.
JSON5 (trailing commas, single quotes, comments) and JSONC (just comments, used in VSCode settings) parse correctly and convert to strict JSON on output. NDJSON / streaming JSON (newline-delimited JSON) is supported in the converter — pick "NDJSON" as input format.
Client-side format / validate / minify works on multi-megabyte files in modern browsers (tested up to 10MB). AI-driven mode caps at 12,000 characters per call. For huge JSON files, format client-side and only send the part you want to explain or convert through AI.
Yes — paste sample JSON and ask "generate a JSON schema". The model produces draft-2020-12 schema with type inference, optional vs required fields based on what appears in the sample, format hints (email, uri, date-time) where detectable. Use for OpenAPI specs, validation libraries, or contract tests.
Client-side ops (format, validate, minify, tree view) never leave your browser. AI ops (generate, explain errors, convert formats) send the JSON to the model, process, and discard — not stored, not used for training. Pick Qwen 3 Coder for maximum privacy on AI ops.
Yes — paste object A and object B in the diff tab. The output highlights added keys, removed keys, and changed values with deep nesting. Output is human-readable side-by-side and structured (RFC 6902 JSON Patch) for programmatic use.
jq is a CLI for transforming JSON via a query language — powerful but requires learning. Free.ai is browser-based and supports natural-language transformations ("extract all emails from the users array, deduplicated"). For frequent CLI users, jq stays faster; for ad-hoc / shareable transforms, Free.ai wins.
Yes — POST to /v1/chat/ with a JSON-specialist system prompt and your input. Useful for in-app JSON validation with AI-friendly error messages. See /api/ for snippets.
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