JSONL Log Field Extractor
Generate named capture groups for newline-delimited JSON logs locally in the browser.
{"timestamp":"2026-04-27T10:30:00Z","status":500,"errorCode":"E_TIMEOUT","message":"upstream timed out"}Code generationLocal-only
JSONL Log Field Extractor
Generate named capture groups for newline-delimited JSON logs locally in the browser.
This tool runs locally in your browser. Your input is not uploaded.
No uploadsNo server logsNo runtime APIsBrowser-only transforms
Prefilled local output
Copy the generated result or open the full tool to adjust inputs locally.
Sample log line
{"timestamp":"2026-04-27T10:30:00Z","status":500,"errorCode":"E_TIMEOUT","message":"upstream timed out"}Regex and parsing snippets
JSONL access example
const record = JSON.parse(line);
const timestamp = record["timestamp"];
const message = record["message"];
const status = record["status"];
const errorCode = record["errorCode"];
Field table
| Field | Capture group |
| --- | --- |
| timestamp | `timestamp` |
| message | `message` |
| status | `status` |
| errorCode | `errorCode` |
Preview
Line 1: no match
Python snippet
import json
record = json.loads(line)
# Access fields directly, for example:
# message = record.get("message")
JavaScript snippet
const record = JSON.parse(line);
// Access fields directly, for example:
// const message = record.message;Examples
How it works
- JSONL Log Field Extractor focuses on extracting useful fields from newline-delimited JSON logs. The sample is prefilled so you can inspect the generated JavaScript and Python named capture groups immediately.
- This page is not a generic regex playground. It is tuned for log parsing workflows: select fields, generate a conservative extraction pattern, preview matches, and copy parser snippets into your own pipeline.
- Regex is best for stable line-oriented logs. If your application emits JSONL, parse JSON rather than matching text; if your log format varies by service version, treat the generated pattern as a starting point and add tests around real samples.
Limitations
- This preset targets a common workflow and should be reviewed against your production environment.
- Generated output is deterministic and local-first, but scheduler, log, or infrastructure dialects can vary.
- Use the full parent tool when you need to adjust fields, ports, options, or sample inputs.
FAQ
Can this parse every newline-delimited JSON logs variant?
No. It generates a practical starter for common formats and shows warnings when manual adjustment is likely.
Are sample logs uploaded?
No. Generation and preview run locally in the browser.
Why use named capture groups?
Named groups make downstream parsing clearer because each extracted value is labeled by field name.
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