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Checkers and validators for faster quality review

Run bounded checks on supplied text, data, files, and configuration before the next step.

USE WITH CONTEXT

Before you use these tools

A checker can surface rule matches and inconsistencies, but it does not replace formal certification or specialist review. Correct the source, rerun the check, and retain evidence when the decision matters.

Choose a focused workspace

SEO & Marketing

Email Subject Line Tester

Review supplied subject and preview-text lengths without sending email or predicting open rates.

Text, Writing & Language

Keyword Density Checker

Measure literal keyword or phrase frequency with a visible density formula.

Developer & Data

DNS Record Lookup Helper

Build validated dig, nslookup, and DNS-over-HTTPS references without making a DNS request.

SEO & Marketing

Keyword Density Checker

Measure literal keyword occurrences and word count without treating density as a ranking score.

SEO & Marketing

Canonical URL Checker

Compare supplied page and canonical URLs locally without fetching, crawling, or asserting indexability.

Developer & Data

JSON Validator

Validate JSON syntax and report its root type, depth, and structural counts.

Developer & Data

XML Formatter

Validate and indent XML locally while blocking document type and entity declarations.

Analytics & Research

A/B Test Significance Helper

Create a bounded, browser-local a/b test significance helper with visible assumptions, review guidance, and downloadable output.

Video, Audio & Media

SRT Formatter

Normalize validated SRT numbering, timing punctuation, whitespace, and cue separation.

Productivity & Business Ops

Safety-Critical Alarm Test Completion Calculator

Measure due safety-critical alarm tests completed with evidence.

Text, Writing & Language

Readability Checker

Estimate English Flesch readability metrics with documented syllable heuristics.

Developer & Data

Regex Tester

Run a bounded JavaScript regular expression and inspect matches, groups, and positions.

Quality Assurance

Accessibility Test Checklist

Create a bounded, browser-local accessibility test checklist with visible assumptions, review guidance, and downloadable output.

Accessible Email Checker

Create a bounded, browser-local accessible email checker with visible assumptions, review guidance, and downloadable output.

Developer & Data

JSON Formatter

Format and validate one JSON value locally with readable two-space indentation.

Accessible Table Checker

Create a bounded, browser-local accessible table checker with visible assumptions, review guidance, and downloadable output.

Developer & Data

JWT Expiry Checker

Explain JWT expiry and not-before timing against the current browser clock.

Video, Audio & Media

Subtitle Timestamp Shifter

Shift validated UTF-8 SRT or VTT cues by one signed millisecond-precision offset.

Legal, Compliance & Policy

Audit Evidence Index

Create a bounded, browser-local audit evidence index with visible assumptions, review guidance, and downloadable output.

Security & Privacy

JWT Expiry Checker

Create a bounded, browser-local jwt expiry checker with visible assumptions, review guidance, and downloadable output.

Travel & Logistics

Luggage Size Checker

Create a bounded, browser-local luggage size checker with visible assumptions, review guidance, and downloadable output.

Accessible Form Label Checker

Create a bounded, browser-local accessible form label checker with visible assumptions, review guidance, and downloadable output.

PDF & Documents

Reorder PDF Pages

Reverse a PDF or define a complete custom page order with validated page ranges.

Design, Color & Branding

Color Contrast Checker

Create a bounded, browser-local color contrast checker with visible assumptions, review guidance, and downloadable output.