String Template Formatter
Format strings with several placeholder styles.
🧩String Template Formatter
All processing happens locallyWhat this tool does
String Template Formatter is a string formatter supporting positional, named and legacy placeholders, implements the standard table both ways and locates invalid bytes instead of silently dropping them.
All four styles can be mixed in one template: pass named values as key=value, positional ones in order, and %s/%d/%f consume arguments sequentially. Separate arguments by newline or comma; use newlines when values contain commas.
How to use it
- Paste or type your content into the input field at the top, or press the sample button to load demo data.
- Adjust the options below the input, such as output format, separators, letter case or precision.
- Press the main button to run the conversion. Results appear instantly in the output panel without a page reload.
- When the result looks right, use the copy button in the corner, or download it as a local file.
Tips and notes
Clean up stray spaces and line breaks before pasting for more accurate results.
FAQ
Yes. Both commas and newlines separate arguments, so put one argument per line when a value contains commas.
Yes, but they count independently: {0} and the first %s both take the first argument. Mixing is error-prone, so pick one style.
The placeholder stays verbatim in the output instead of becoming empty, so a missing value is obvious.
The bytes are invalid in the chosen encoding — usually the wrong codec.
Yes. The tool is completely free with no usage limits, and you never need an account or a sign-in.
No. All processing runs locally in your browser, so the input never reaches a server and is never logged or stored.
Yes. The layout is mobile-first, so inputs and buttons stay comfortable on phones and tablets in both orientations.
Yes. A copy button in the output panel puts the result on your clipboard, and you can also download it as a text file.