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Data Format Converter — Free Online

Convert between JSON, YAML, TOML, and CSV instantly with this free online data format converter. Swap formats with one click, no sign-up required.

What is a Data Format Converter?

A data format converter is a tool that transforms structured data from one serialization format to another. Modern software development uses multiple data formats for different purposes: JSON (JavaScript Object Notation) is the dominant format for web APIs and configuration; YAML (YAML Ain't Markup Language) is popular for CI/CD pipelines, Kubernetes manifests, and human-editable configs; TOML (Tom's Obvious Minimal Language) is used by Rust's Cargo, Python's pyproject.toml, and other build tools; CSV (Comma-Separated Values) is the universal format for spreadsheets and tabular data. Converting between these formats manually is tedious and error-prone — this tool parses the input format, creates an intermediate data structure, and serializes it into the target format automatically.

How to Use This Free Online Data Format Converter

  1. Select the input format (JSON, YAML, TOML, or CSV) from the left dropdown.
  2. Select the desired output format from the right dropdown.
  3. Paste your data into the input text area. The conversion happens in real time.
  4. Use the swap button (↔) to reverse input and output formats and switch the converted output back into the input field.
  5. Click the Copy button to copy the converted result to your clipboard.

Common Use Cases for Data Format Conversion

  • Converting API responses to YAML configs — Take JSON output from an API and convert it to YAML format for use in Kubernetes manifests, Docker Compose files, or Ansible playbooks.
  • Migrating configuration between tools — Convert TOML configuration (e.g. pyproject.toml) to JSON or YAML when switching build systems or tools that require a different format.
  • Exporting data to spreadsheets — Convert JSON arrays or YAML lists into CSV format that can be opened directly in Excel, Google Sheets, or other spreadsheet applications.
  • Importing CSV data into applications — Parse CSV files from databases or exports and convert them to JSON for use in web applications, APIs, or NoSQL databases.
  • Learning new data formats — Quickly see how the same data looks in different formats to understand YAML indentation, TOML table syntax, or CSV header conventions.

FAQ

Can all data be converted between all formats?
Not always. JSON, YAML, and TOML can represent nested objects and arrays, so they convert well between each other. CSV is inherently flat (rows and columns), so complex nested data may not convert cleanly to CSV. When converting to CSV, the tool flattens the top-level array of objects into columns and rows.
Does YAML preserve data types during conversion?
YAML has richer type inference than JSON — for example, it can interpret 'true', 'yes', and 'on' as booleans, and bare numbers as integers or floats. This tool uses js-yaml's default schema which follows the YAML 1.2 spec, so type handling is standard and predictable.
What TOML features are supported?
This tool uses smol-toml which supports TOML v1.0 including tables, inline tables, arrays of tables, multiline strings, datetime types, and all numeric formats. However, TOML does not support null values, so any null fields in your data will need to be handled.
Is this tool free and private?
Yes. All conversions run entirely in your browser using JavaScript libraries (js-yaml, smol-toml, papaparse). No data is sent to any server, and no sign-up is required.

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