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// about this tool

Log File Analyzer Online

Updated 2026-08-19

Search a log file the way you would with grep, right in your browser. Paste in a log — a server log, a CI run, an app's stdout — type a pattern, and every matching line lists live with its line number. Nothing is uploaded, so it is safe for logs that carry hostnames, IPs, or request data you would not want to paste into a hosted tool.

Plain text search is the default; flip on regex mode for wildcards and character classes, invert match to filter out noise like health checks, and add before/after context lines to see what happened around a crash without scrolling through the whole file by hand.

// how to use

  1. 1 Paste your log file or output into the log text panel — nothing is uploaded.
  2. 2 Type a search term or regex pattern; matching lines list live as you type, with the line number shown.
  3. 3 Toggle case-insensitive, invert match, or regex mode, and add before/after context lines to see the surrounding log entries.

// examples

Find every error line
Input
pattern: ERROR  text: a 500-line app log with 2 ERROR lines among mostly INFO lines
Output
2 matches — lines 47 and 312, each with 1 line of context
Exclude noisy health-check lines
Input
pattern: /health  invert: on  text: a log mixing health-check pings with real requests
Output
All lines except the /health pings — 480 of 500 lines shown
Find every occurrence of a request ID
Input
pattern: req_[a-f0-9]{8}  regex: on  text: a server log with request IDs
Output
14 matches, one line per request

// common uses

Scanning a server log for error lines Filtering out noisy health-check or heartbeat lines Finding every line mentioning a specific request ID or IP address Pulling the surrounding context around a crash line from a large log dump

// faq

Does this upload my log file anywhere?
No. Searching happens entirely in your browser — nothing is sent to a server, so it is safe for logs containing private hostnames, IPs, or request data.
What is the difference between this and the Regex Tester?
Regex Tester is built for debugging a single pattern against arbitrary text with capture-group feedback. Log File Analyzer is built for scanning a whole log — line numbers, invert match, and before/after context are grep features regex debugging doesn't need.
Can I search with plain text instead of a regex?
Yes — that is the default. Turn on regex mode only when you need wildcards, character classes, or anchors.
What does "invert match" do?
It shows every line that does NOT match your pattern — the same as grep -v — useful for filtering out noisy lines like health checks or heartbeats.
How do context lines work?
Context before/after add N surrounding lines around each match, the same as grep -B and -A. A "--" divider appears where two match blocks are not adjacent, so you can tell separate incidents apart.

// works with your data

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Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/log-file-analyzer \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"text":"pattern: ERROR text: a 500-line app log with 2 ERROR lines among mostly INFO ..."}'