Data & Test Data
Convert and format data such as JSON, CSV and YAML, and generate dummy data for testing. Prepare the data you need for development checks on the spot.
20 tools・Ordered by measured page views over the last 90 days.
Japanese Phone Number Generator
Randomly generate Japanese phone numbers (mobile, landline, toll-free). Hyphen on/off and CSV export.
Test Data Generator
Generate fictional test data — names, emails, phones, addresses, UUIDs — by count and columns. Export as CSV/TSV/JSON/SQL.
Japanese Name Generator
Randomly generate Japanese full names with furigana and romaji. Export sample names as test data by count to CSV.
JSON Formatter & Validator
Paste JSON to pretty-print or minify. Syntax errors are reported with line and column.
Japanese Address Generator
Randomly generate Japanese addresses (postal code, prefecture, city, block, building). Export as CSV for form checks.
CSV ⇄ JSON Converter
Convert between CSV and a JSON array, with header and delimiter options.
JSON Diff
Deep-compare two JSON documents and see added, removed, and changed keys with paths like a.b[2], color-coded. Key order is ignored; nesting is compared recursively.
Placeholder Image Generator
Create mockup placeholder images with a custom size, background and text colour. Save as PNG, JPEG or WebP.
Random Date Generator
Generate random dates for test data from a chosen range, count and format. Sorting and duplicate removal included.
YAML / JSON Converter
Convert between YAML and JSON in both directions. Syntax errors are shown with line and column numbers, and the indent width is selectable.
Email Address Generator
Randomly generate dummy email addresses for testing using safe reserved domains like example.com. Export to CSV.
JSON Relationship Map
Draws JSON nesting as levels. Select an element to color-code its parent, children, siblings and ancestors.
Dummy Company Name Generator
Randomly generate fictional Japanese company names in Japanese and English. Choose industry and legal entity type, export as CSV.
Test Barcode Number Generator
Generate batches of JAN/EAN-13, UPC-A, ISBN-13 and ITF-14 test codes with a correct check digit. In-store prefixes that cannot collide with real products are selectable.
.env and JSON Converter
Convert between a .env file and JSON. Handles comments, the export prefix, quoting, escapes and duplicate keys, and reports warnings.
CSV ⇄ Markdown Table
Convert CSV or TSV into a Markdown table and back, handling quoted commas, line breaks and pipe characters.
JSONL / JSON Converter
Convert between JSONL (NDJSON, one JSON per line) and a JSON array in both directions. Broken lines are reported with their line number.
JSON Schema Generator
Generate a JSON Schema (draft 2020-12) from sample JSON. Arrays are merged across every element; required and format inference are optional.
JSON to TypeScript
Paste JSON to generate TypeScript interfaces or types. Nested objects become separate named types and array element types are merged. Runs in your browser.
CSV to vCard (.vcf)
Build a vCard (.vcf) file from a contacts CSV. Name, phone, email, company and title columns are detected automatically and merged into one downloadable file.