Free Online JSON Tools
Olutil stands for Online Utilities — a growing suite of privacy-first, browser-native web tools. This sub-site brings you a complete suite of JSON utilities that run entirely in your browser. Format, validate, minify, convert, diff, query and generate schemas — all in one place. 100% Local Processing
JSON Formatter
Beautify and pretty-print raw JSON with clean indentation for easy reading and debugging.
JSON Validator
Detect syntax errors instantly with clear, friendly error messages pointing to the problem.
JSON Minifier
Compact large JSON by removing all whitespace and newlines for faster storage and transfer.
JSON Tree Viewer
Explore JSON structure interactively with collapsible nodes and color-coded types.
JSON Diff
Compare two JSON strings and see exactly what was added, removed or changed.
JSON to CSV
Convert JSON arrays into standard CSV with proper escaping and auto-detected headers.
CSV to JSON
Map CSV headers to JSON object keys automatically with support for quoted fields.
JSON to YAML
Convert JSON objects to clean, human-readable YAML with proper indentation.
YAML to JSON
Parse YAML text into formatted JSON with support for anchors, aliases and multi-document.
JSONPath Tester
Test JSONPath expressions against JSON samples and get matched results instantly.
JSON Schema Generator
Auto-generate JSON Schema from sample data with type inference and required field detection.
JSON Pretty Print
Format minified JSON into clean, readable output with proper indentation.
JSON Sorter
Recursively sort all object keys alphabetically for consistent output.
JSON Escape
Escape special characters for safe embedding in JSON strings.
JSON Unescape
Decode JSON-escaped strings back to their original form.
JSON Size Analyzer
Measure character count, byte size, nesting depth and compression ratio.
JSON Fixer
Auto-repair trailing commas, single quotes, comments and unquoted keys.
JSON Flatten
Convert nested objects into flat dot-notation keys for data processing.
JSON Unflatten
Convert flat dot-notation keys back into nested JSON objects.
JSON Merge
Deep-merge two JSON objects recursively, concatenating arrays.
JSON Deduplicator
Remove duplicate elements from a JSON array by full JSON comparison.
JSON Filter
Filter JSON array elements using JavaScript expressions.
JSON Field Extractor
Extract a specific field from JSON objects by dot-notation path.
JSON Key Rename
Batch rename object keys throughout nested JSON recursively.
JSON Path Extractor
List every field path and value in a JSON document.
JSON to Query String
Transform JSON objects into URL query parameters.
Query String to JSON
Parse URL parameters into a JSON object.
JSON to Base64
Encode JSON strings as Base64 for safe transport or storage.
Base64 to JSON
Decode Base64 strings back to formatted JSON.
JSON to Markdown Table
Transform JSON arrays into Markdown tables for documentation.
JSON to HTML Table
Generate HTML table markup from JSON arrays.
JSON to Properties
Flatten JSON into key=value .properties file format.
Properties to JSON
Parse key=value .properties files into JSON objects.
JSON to ENV
Transform JSON into .env format with uppercase keys.
JSON Lines to JSON
Parse newline-delimited JSON (NDJSON) into a single JSON array.
JSON to NDJSON
Split JSON arrays into newline-delimited JSON lines.
Random JSON Generator
Generate random test JSON objects with nested structures.
JWT Decoder
Decode JWT tokens to view header and payload as formatted JSON.
JWT Validator
Check JWT structure, decode claims and verify expiration.
JSON to cURL
Create cURL commands from JSON request bodies.
cURL to JSON
Extract JSON request body from cURL commands.
How It Works
All tools on this site perform their work locally in your browser. Your data is never sent to any server, making these tools ideal for sensitive or confidential JSON payloads. Simply paste your JSON, click the run button, and copy the result.
- Runs 100% in your browser — no uploads, no server dependencies
- Fast performance, even with large JSON files
- No sign-up, no accounts, no tracking pixels
- Works on desktop, tablet and mobile devices
Frequently Asked Questions
Is my data safe?
Yes. All processing runs locally in your browser. Your data is not uploaded to any server. You can even use these tools while offline once the page is loaded.
Do I need to install anything?
No. Every tool works directly in your web browser using JavaScript. No plugins, extensions or software installation required.
Can I use these tools for large JSON files?
Yes. The tools are optimized for performance and can handle JSON files of several megabytes without issue.