Static + Browser-Only

Log Regex Tester and Validator Online

Test regex rules against JSON online. Put regex rules JSON on the left, validate a log payload on the right, and highlight invalid or missing fields directly in the browser.

This is useful for log review, field validation, and regex-based line checks without uploading data.

Rules

Regex rules JSON

Paste regex rules JSON on the left and a log payload on the right.

Payload

Payload Logs

Validated payload with field-level regex highlights will appear here

What Is It

What is a log regex tester and validator?

This page validates logs against a rules JSON object where each field contains a regex pattern. It helps teams test whether line-based keys and values match expected formats before sharing, debugging, or using those logs elsewhere.

Use Cases

When should you validate logs with regex rules?

Check API fixtures before QA or release review
Validate form payload patterns like email, phone, and member IDs
Review logs and extracted key-value lines against internal standards
Highlight log lines that break expected regex rules

Features

What this log regex validation tool can do

Use a JSON object of regex rules as the source of truth
Validate fields such as email, status, and memberId
Highlight invalid and missing values in log payloads
Run locally in the browser with no upload

FAQ

Common questions

How do I test a payload against regex rules?

Paste your regex rules JSON on the left, paste the matching payload format on the right, and run validation. Invalid or missing fields are highlighted in red inside the payload viewer.

Can I validate log fields?

Yes. Nested objects are supported, so rules like customer.memberId and customer.email work when the log structure matches.

Does this work only for logs?

Yes. This page is focused on log validation. Other regex pages are available for XML, HTML, CSV / TSV, SQL, logs, plain text, and HTTP payloads.

Does this upload the rules or payload?

No. Validation runs locally in the browser and no rules JSON or payload content is uploaded during the workflow.

Why log regex validation matters before sharing or testing logs

Teams often assume sample payloads are valid until a downstream system rejects them. A log regex validator makes those formatting problems visible before a payload reaches QA, support, docs, vendors, or AI workflows.

This is useful for log fields such as emails, phone numbers, IDs, member IDs, and status values where format errors are easy to miss.

Teams often search for a free regex tester online when they need to validate field formats, check sample payloads, enforce naming rules, or catch invalid values before QA, release review, or external sharing. A browser-only regex validator is especially useful when payloads, logs, or request examples should stay local and should not be uploaded to a remote validator.

Examples

Example log rules and payload

The rules JSON defines regex patterns, and the payload is log text with invalid values highlighted.

Regex rules JSONValidation rules

{
  "email": "^[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,}$",
  "phone": "^\\d{3}-\\d{3}-\\d{4}$",
  "status": "^(active|pending|paused)$",
  "customer": {
    "memberId": "^mem_\\d{3,}$"
  }
}

Payload LogsInvalid fields highlighted

{
  "email": "john@example.com",
  "phone": "2045550199",
  "status": "trial",
  "customer": {
    "memberId": "204"
  }
}