Colorize Text with Regex Rules

Paste logs or command output, write color: regex rules, and export highlighted ANSI text or themed HTML.

Highlight logs and command output with repeatable rules

Text Colorizer applies a stack of color: regex rules to every line of pasted text. It is useful for turning plain CI logs, command output, server logs, or grep results into terminal-colored ANSI text or self-contained HTML you can paste into a report.

Rules are evaluated from top to bottom. Each rule uses the text before the first colon as the style and the text after it as a Rust regular expression. Earlier rules win where matches overlap, so put the most important patterns first.

Worked example

Paste this text:

INFO service started
WARN retrying request
ERROR database timeout

Then use these rules:

bold red: \bERROR\b
yellow: \bWARN(ING)?\b
green: \bINFO\b

Choose ANSI terminal escapes to paste into a compatible terminal or HTML <pre> to produce a small themed block for a web page or incident note.

Rule syntax

red: ERROR colors matching substrings red.
bold red: \bERROR\b adds attributes before the foreground color.
green on black: \bOK\b sets a background with on <color>.
#3465a4 underline: https?://\S+ uses a custom hex color.
Turn on Color whole matching lines when you want a matching ERROR or FAIL to color the entire line.

Limits and edge cases

Input text is capped at 512 KiB and rules are capped at 200 lines.
Rules use Rust regular expressions, not JavaScript-specific regex features.
HTML output escapes unmatched text before wrapping styled matches, so pasted < and & are safe text.
ANSI output includes escape characters; use HTML output when a destination does not interpret ANSI.

FAQ

What colors and attributes can I use?

Named colors include black, red, green, yellow, blue, magenta, cyan, white, gray/grey, and bright variants such as brightred and brightyellow. You can also use #rgb or #rrggbb hex colors. Attributes include bold, dim, italic, underline, blink, reverse, and strike.

What happens when two rules match the same text?

The first rule in the list wins for the overlapping characters. Put high-priority rules such as ERROR before broad catch-all patterns like timeout|failed|error.

Can I color an entire log line instead of just the matching word?

Yes. Enable Color whole matching lines. The first rule that matches anywhere on a line styles the whole line, which is useful for CI statuses or severity-based log highlighting.

When should I choose ANSI versus HTML?

Choose ANSI when the result will be viewed in a terminal or a tool that understands escape codes. Choose HTML when you want a portable preview block for documentation, incident notes, or web pages.

Developer & Automation Access

Run it from the terminal

Same engine as this page, headless — via the gizza CLI:

gizza tool text-colorizer "INFO service started
WARN retrying request
ERROR database timeout" 'rules=bold red: \bERROR\b
yellow: \bWARN(ING)?\b
green: \bOK\b'

New to the CLI? Get gizza →

Open it by URL

Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:

https://gizza.ai/tools/text-colorizer/?text=INFO%20service%20started%0AWARN%20retrying%20request%0AERROR%20database%20timeout&rules=bold%20red%3A%20%5CbERROR%5Cb%0Ayellow%3A%20%5CbWARN%28ING%29%3F%5Cb%0Agreen%3A%20%5CbOK%5Cb&output=ansi&theme=dark&ignore_case=true&whole_line=true

Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.