Data & Format Tools
Free Online Data & Format Tools
Data format converters and generators that run entirely in your browser. Convert between JSON, CSV, YAML, XML, and TOML, generate realistic mock data for testing, create JSON schemas, and build form test cases — with no data sent to a server.
Data format tools for developers and data engineers
Modern applications consume and produce data in JSON, CSV, YAML, XML, TOML, and a dozen other formats. Switching between them is a constant task — for API integration, config file management, database seeding, and test data preparation.
JSON has become the lingua franca of web APIs, but CSV remains dominant for spreadsheets and data pipelines. YAML is preferred for configuration files (Kubernetes, GitHub Actions, Docker Compose) because it is more readable than JSON. Knowing when to use which format — and how to convert between them reliably — is a core developer skill.
All conversion logic runs entirely in your browser with no server round-trip. Large CSV files, complex nested JSON, and multi-document YAML files all process instantly at native JavaScript speed.
Data & Format best practices
FAQ
Common questions
What is the difference between JSON and YAML?
JSON uses strict syntax — double quotes for keys, no trailing commas, no comments. YAML is a superset of JSON with more relaxed syntax, support for comments, and cleaner multi-line strings. YAML is popular for config files; JSON is the standard for API payloads.
How do I convert a CSV with nested data?
Nested JSON cannot be represented directly in CSV. The JSON to CSV converter flattens nested objects into dot-notation column names (e.g., address.city). For deeply nested structures, consider JSON or YAML instead of CSV.
What is JSON Schema?
JSON Schema is a vocabulary for describing the structure of JSON data. It specifies types, required fields, string patterns, numeric ranges, and array constraints. Use it to validate API request/response bodies and catch schema drift early.
What data types does the mock data generator support?
The mock data generator supports names, emails, phone numbers, addresses, dates, UUIDs, booleans, integers, floats, company names, and custom strings. Export as JSON or CSV for use in tests, database seeding, or Storybook stories.
What is TOML and when should I use it?
TOML (Tom's Obvious Minimal Language) is a configuration format designed to be easy to read. It maps cleanly to a hash table and is used by Cargo (Rust), Hugo, and Poetry (Python). Use it when you want a config format that's more structured than YAML but simpler than JSON for humans.