How to Format and Validate JSON, YAML, and XML Online
JSON, YAML, and XML are data formats used in configuration files, APIs, and data exchange. Malformed or improperly formatted data causes errors and makes code difficult to read. This guide shows you how to format and validate JSON, YAML, and XML using fixie.tools — a free online formatter that checks syntax, highlights errors, and beautifies your data, no signup required.
Step 1: Open the Data Formatter
Go to fixie.tools/formatter in your web browser. The tool supports JSON, YAML, and XML formatting and validation with no account required. All processing happens in your browser for privacy — your data is never uploaded or stored.
Step 2: Select Your Data Format
Choose the format you want to work with: JSON, YAML, or XML. The tool auto-detects the format in most cases, but selecting explicitly ensures proper syntax checking. Each format has its own validation rules and formatting conventions.
Step 3: Paste Your Data
Paste your data into the input editor. This could be API responses, configuration files, or any JSON, YAML, or XML content. The editor supports large files (up to 10MB) and provides syntax highlighting to help identify structure even before formatting.
Step 4: Validate and Check for Errors
Click the validate button to check for syntax errors. The tool highlights errors with red underlines and displays error messages explaining what's wrong and where. Common issues include missing quotes, unclosed brackets, invalid escape sequences, or incorrect indentation in YAML. Fix any errors before proceeding to formatting.
Step 5: Format and Beautify
Once validation passes, click the format button to beautify your data. The tool adds proper indentation, line breaks, and spacing to make your data readable. Choose your preferred indentation (2 spaces, 4 spaces, or tabs). Copy the formatted output or download it as a file. You can also minify (compress) formatted data to reduce file size for production use.