PTPureToolkit
Code generationLocal-only

Regex Log Pattern Generator

Paste sample logs, choose a preset or auto-detect, select fields, and generate JavaScript and Python named-capture extraction patterns, parsing snippets, explanations, and match previews.

This tool runs locally in your browser. Your input is not uploaded.

No uploadsNo server logsNo runtime APIsBrowser-only transforms
Options
Fields to extract

MVP limit: 1-20 log lines, up to 200KB.

Generated log extraction pattern

Generate a log extraction pattern to see regex, preview, and parsing snippets.

Examples

Nginx access log example

Generate named groups for IP, timestamp, request, status, and user agent fields.

203.0.113.7 - - [27/Apr/2026:10:12:44 +0000] "GET /api/users?id=1 HTTP/1.1" 200 1234 "-" "Mozilla/5.0"

Apache log example

Apache combined logs share the same extraction shape as common access logs.

198.51.100.4 - frank [27/Apr/2026:10:15:12 +0000] "POST /checkout HTTP/1.1" 500 532 "-" "curl/8.0"

How it works

  1. What this log regex generator does: creates extraction patterns with named capture groups for supported log formats.
  2. Named capture groups explained: each selected field is emitted as a JavaScript (?<field>...) group and a Python (?P<field>...) group.
  3. When regex is not enough: JSONL logs should be parsed as JSON instead of matched with regex whenever possible.

Limitations

  • The tool is not a generic regex tester; it generates deterministic extraction patterns for known log presets.
  • Custom log formats may need manual adjustment after generation.
  • JSONL mode prefers JSON field access examples over regex when the input is valid JSON lines.

FAQ

Is this a general-purpose regex tester?

No. It is designed to generate extraction patterns for logs using known presets and named capture groups.

Why does JSONL mode avoid regex?

Structured JSON logs are safer and more reliable to parse with JSON.parse or json.loads than with regular expressions.

Are the generated regexes safe?

The patterns use anchored templates and bounded character classes to avoid catastrophic backtracking in the supported formats.

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