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Log Parser & Highlighter

Paste Logs

Paste your log file above to start parsing and filtering.

What This Tool Does

Paste a log file to parse, filter, and search it in the browser — nothing is uploaded. The parser auto-detects JSONL, Python logging, syslog, nginx access, and generic timestamped formats, extracts timestamps and levels, and filters by level or regex. Nginx access lines carry no level, so the tool derives one from the HTTP status: 5xx maps to ERROR, 4xx to WARNING.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Programmatic Access

Log Parser & Highlighter is also callable as a free HTTP JSON API at https://aidevhub.io/api/log-parser/ — GET with query parameters or POST with a JSON body, no authentication, CORS enabled, 50 requests/day per IP. Responses return { ok, tool, result, meta }. 

curl -s -X POST https://aidevhub.io/api/log-parser/ \
  -H "Content-Type: application/json" \
  -d '{"logs":"2026-07-12T10:00:00Z ERROR db timeout\n2026-07-12T10:00:05Z INFO retry succeeded"}'

Machine-readable contract: /api/tool/log-parser.json All API endpoints: /agents/ LLM site index: /llms.txt

Agent Invocation

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Dedicated API endpoint

Deterministic outputs, machine-safe contracts, and production-ready examples.

Dedicated API

https://aidevhub.io/api/log-parser/

OpenAPI: https://aidevhub.io/api/openapi.yaml

GET /api/log-parser/ GET log-parser
POST /api/log-parser/ POST log-parser

Unified Runtime API

https://aidevhub.io/api/tools/run/?toolId=log-parser&a=...

GET and POST are supported at /api/tools/run/ with identical validation and limits.

Limit: 30 req / 60s, input max 256 KB.

How to Use Log Parser & Highlighter

  1. 1

    Paste your log file

    Paste raw logs (syslog, application logs, or JSON logs) into the input. Supports multiline entries and mixed log formats.

  2. 2

    Select log level filters

    Filter by severity: ERROR, WARN, INFO, DEBUG, TRACE. Choose multiple levels to focus on the logs that matter.

  3. 3

    Enable syntax highlighting

    The parser automatically highlights timestamps, error codes, stack traces, and key-value pairs in different colors for quick scanning.

  4. 4

    Search and analyze

    Use the search field to find specific terms, correlation IDs, or IP addresses. The parser shows frequency counts and clustering for patterns.

  5. 5

    Export filtered results

    Download the parsed and filtered logs as CSV or JSON for further analysis in spreadsheets or data tools.

Frequently Asked Questions

What is Log Parser & Highlighter?
Log Parser & Highlighter analyzes log files with syntax highlighting, level filtering, and search. It auto-detects formats including JSONL, Python logging, syslog, and nginx access logs.
How do I use Log Parser & Highlighter?
Paste your log content into the editor. The tool auto-detects the format and applies syntax highlighting. Use the level filter to show only errors or warnings, and search to find specific entries.
Does Log Parser & Highlighter store or send my data?
No. All processing happens entirely in your browser. Your log data never leaves your device — nothing is sent to any server.
Which log formats are supported?
The tool auto-detects and highlights JSONL structured logs, Python logging output, syslog format, and nginx access/error logs. It also supports generic log patterns with timestamp and level detection.

How do I parse and filter a log file online without uploading it?

Paste the log. The parser samples the first non-empty lines, detects the format, and shows a badge with the result; each line is then split into timestamp, level, and message, and the stats bar reports totals per level plus the time span from first to last timestamp. All of it happens in the page — there is no upload step.

Step by step

  1. Paste log content, or load the sample to see the parsed view.
  2. Confirm the detected format badge — JSONL, Python, syslog, nginx, or generic.
  3. Uncheck levels you want hidden; the per-level counts next to each checkbox come from the full file.
  4. Search with plain text or a regular expression — matches highlight inline and the match count updates live.
  5. Copy or download the filtered result. The export contains the raw log lines, so it drops straight into a ticket or a diff.

Formats this parser detects

Format Recognized shape What gets extracted
JSONL Each line is a JSON object Timestamp from timestamp/time/ts/@timestamp; level from level/severity/loglevel; message from message/msg/text
Python logging 2026-02-12 15:30:45,123 INFO message Timestamp, level, message
syslog Feb 12 15:30:45 host proc[pid]: message Timestamp and message; level from keywords in the message
nginx access IP - - [date] "request" status bytes Timestamp and request line; level derived from the HTTP status code
Generic ISO-style timestamp prefix, bracketed or bare Timestamp and message; level from keywords

Detection as implemented in this parser: a format wins when at least half of the sampled lines match its pattern (JSONL requires 70%). Mixed-format files fall back to generic keyword-based level extraction.

How does level filtering work when lines have no level?

Lines without a detectable level always stay visible, so stack traces and continuation lines keep their context when you filter to ERROR. Keyword extraction looks for DEBUG, INFO, WARNING, ERROR, or CRITICAL anywhere in the line, and nginx status codes map to levels — which turns an access log into something you can triage by severity even though the format has no level field.

Can it handle large log files?

Yes, within browser memory — there is no network quota because there is no upload. Above 1,000 lines the viewer switches to virtualized rendering and only draws the visible slice, so scrolling a six-figure-line paste stays responsive.

Do my logs leave the browser?

No. Production logs routinely carry IP addresses, user identifiers, session tokens, and internal hostnames. Parsing and filtering run in the page, nothing is stored, and closing the tab discards the data — the safe default when the log you are debugging came from a live system.