Static + Browser-Only

HTML Regex Tester and Validator Online

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

This is useful for API payload review, fixture validation, nested field checks, and HTML regex extraction workflows without uploading data.

Rules

Regex rules JSON

Paste regex rules JSON on the left and an HTML payload on the right.

Payload

Payload HTML

Validated payload with field-level regex highlights will appear here

What Is It

What is an HTML regex tester and validator?

This page validates HTML against a rules JSON object where each field contains a regex pattern. It helps teams test whether markup values and text nodes match expected formats before sharing, debugging, or publishing HTML elsewhere.

Use Cases

When should you validate HTML with regex rules?

Check API fixtures before QA or release review
Validate form payload patterns like email, phone, and member IDs
Review HTML templates, email markup, and snippets against internal standards
Highlight HTML text content that breaks expected regex rules

Features

What this HTML regex validation tool can do

Use a JSON object of regex rules as the source of truth
Validate HTML paths such as card.email and card.status
Highlight invalid and missing values in HTML 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 nested HTML fields?

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

Does this work only for HTML?

Yes. This page is focused on HTML 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 HTML regex validation matters before sharing or testing payloads

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

This is useful for HTML fields such as emails, status text, IDs, and data attributes 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 HTML rules and payload

The rules JSON defines regex patterns, and the payload is an HTML snippet 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 HTMLInvalid fields highlighted

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