Data Converter
Convert between JSON, CSV, YAML and TOML data formats. Paste or upload. Free, browser-based.
Input
Output
JSON Input
CSV Output
About Data Converter
Modern software development involves constantly moving data between different systems, each with its own preferred format. REST APIs return JSON, configuration files often use YAML or TOML, spreadsheets work with CSV, and analytics pipelines might need flat table structures. Converting between these formats manually is tedious and error-prone — one missed comma or incorrect indentation can invalidate an entire file.
Our Data Converter handles bidirectional transformation between JSON, CSV, YAML, and TOML formats. Pick the input format and the output format with the buttons above each panel, and if the parser rejects your input the conversion stops and shows you the parser's own error message instead of producing garbage. Nested JSON objects convert to flattened CSV using dot notation (e.g., a `user.name` key becomes a "user.name" column header), and array items keep their index in the path (`tags.0`, `tags.1`), making complex API responses accessible in spreadsheet tools.
You can paste data directly into the input field or upload a file. The output can be copied to your clipboard or downloaded as a new file, and the ⇄ button between the format rows sends the output back into the input so you can chain another conversion. Everything runs locally in your browser — your configuration files, API keys, and structured data stay completely on your device.
How to Use Data Converter
- 1Paste your source data into the input field, or click "Upload file" to load a .json, .csv, .yaml, .yml or .toml file.
- 2Pick the input format with the JSON / CSV / YAML / TOML buttons in the "Input" row.
- 3Pick the target format with the buttons in the "Output" row.
- 4Click the Convert button at the bottom — if the input is malformed, the parser error appears below the panels instead of an output.
- 5Copy the output to clipboard or click "Download" to save the converted file.
- 6Click the ⇄ button between the two format rows to push the output back into the input and chain another conversion.
Use Cases
- →Convert a JSON API response to CSV for analysis in Excel or Google Sheets
- →Transform a YAML configuration file to JSON for use in a JavaScript application
- →Convert TOML config files to YAML for compatibility with deployment pipelines
- →Flatten a nested JSON structure to a CSV for database import or reporting
- →Convert CSV data exports from a CRM or analytics tool to JSON for API consumption
- →Reformat configuration files when migrating between tools that use different formats
Tips
- ✓If the parser rejects your input, its error message appears right below the panels — fix it and hit Convert again
- ✓Arrays of objects convert to CSV rows with the object keys becoming column headers
- ✓CSV output needs an array at the top level — a single JSON object will be rejected with a clear message
- ✓Nested JSON objects are flattened with dot notation (e.g., user.address.city) in CSV mode
- ✓YAML is the most human-readable format — great for configuration files read and edited manually
- ✓TOML is commonly used in Rust (Cargo.toml), Python packaging (pyproject.toml) and Hugo
- ✓For very large files (several MB), processing may take a few seconds entirely in your browser
Frequently Asked Questions
JSON (JavaScript Object Notation), CSV (Comma-Separated Values), YAML (YAML Ain't Markup Language) and TOML (Tom's Obvious, Minimal Language). All conversions are bidirectional — any format can be the input or output.
The JSON input must be an array of objects. Each object becomes a CSV row, with the object keys becoming column headers. If objects have different keys, missing values are left empty. Nested objects are flattened into dot-notation columns — { "user": { "name": "Ada" } } becomes a user.name column — and array items keep their index in the path, such as tags.0 and tags.1.
Yes. Click the "Upload file" button above the input panel to load a .json, .csv, .yaml, .yml or .toml file directly from your computer. The file is read in your browser — it is never sent to a server.
TOML is a configuration file format designed to be easy for humans to read and write. It's commonly used for configuration files in Go, Rust and other languages (e.g., Cargo.toml).
Both YAML and JSON can represent the same data structures. YAML uses indentation instead of brackets and is more human-readable. JSON is stricter, requires quotes around strings and is more widely supported in programming environments.
The Swap button reverses the input and output format selection and moves the current output text into the input panel. This lets you quickly do a round-trip conversion or continue working with the converted output.