Validate before transforming
Start by validating the original input. Formatting invalid data can hide the location of the real problem or create a result that looks correct but cannot be parsed. Keep an untouched copy until the conversion is complete.
For JSON, XML and YAML, use a validator that reports syntax errors before applying indentation. For tabular data, verify the delimiter, headers and quoting rules before converting CSV to JSON or HTML.
Choose the target format by use case
JSON is a strong default for APIs and browser applications. YAML is easier to edit by hand for configuration files. XML remains common in feeds and enterprise integrations, while CSV is suitable for flat tables and spreadsheet exchange.
SQL formatters improve readability but do not execute or guarantee a query is valid for a specific database. Treat formatting as a review aid, not as a database test.
Protect real payloads
API responses and configuration files may contain tokens, email addresses or internal identifiers. Local browser tools reduce exposure because the content stays on the device. Remove secrets before sharing the formatted output with another person or service.