Add Prefix or Suffix

How to use Prefix and Suffix

1. Paste lines or select a local text or Markdown document.
2. Enter prefix, suffix, or numbering settings and choose which lines qualify.
3. Check the first 100 changed lines, then copy or download the complete result.

Supported behavior

Add Prefix or Suffix decorates selected lines without manually editing each one. Enter literal text to prepend, append, or both, then target every line, only non-empty lines, lines containing a literal value, or lines matching a regular expression. It can also add sequence numbers with a configurable starting value, zero-padding width, and separator. Numbering works even when both prefix and suffix are empty. The first 100 changed lines are previewed so alignment and matching can be checked before exporting. If a regular expression is invalid, the source remains unchanged and the error is shown rather than producing partial output. Local .txt and .md files, match rules, and generated lines stay entirely in your browser and are never uploaded. Prefixes and suffixes are literal output content; they are not templates or executable code. Numbering follows the lines selected by the chosen condition, so confirm whether empty or unmatched lines should consume a number in your intended workflow.

• The preview shows only the first 100 changed lines, although the full valid input can be processed.
• Regex conditions time and select lines; they do not provide capture-based replacement templates.

Examples

                apples
pears
plums
              

                draft
review
publish
              

Common use cases

• Turn a list of names into Markdown bullet items.
• Add padded sequence numbers to a plain-text inventory.
• Append a marker only to lines matching a status pattern.

Frequently asked questions