Math & Numbers
Calculate sample variance with the n - 1 denominator for estimating spread from a sample dataset
sample-variance-calculatorMath & Numbers
Calculate arithmetic, geometric, and Fibonacci sequences, including the nth term, the first terms, and the partial sum
sequence-calculatorAI Tools
Convert scanned or image-heavy PDFs into Markdown with OpenDataLoader hybrid OCR, with a graceful fallback when the hybrid backend is unavailable
scanned-pdf-ocr-to-markdownMath & Numbers
Add, subtract, multiply, and divide values written in scientific notation, then return standard, scientific, and engineering forms
scientific-notation-calculatorMath & Numbers
Convert numbers between standard decimal format and scientific notation, with optional engineering notation output
scientific-notation-converterValidation
Simulate the reading order and spoken semantics a screen reader may expose from a URL or raw HTML, then flag likely accessibility gaps
screen-reader-simulation-testerMath & Numbers
Estimate required sample size for proportions or means using confidence level, margin of error, and optional finite population correction
sample-size-calculatorText Processing
Automatically detect and mask sensitive information like phone numbers, emails, ID cards, and bank cards in text
sensitive-data-maskerHealth
Calculate running pace, speed, and time for various distances
running-paceFitness
Calculate calories burned while running
running-burn-calculatorValidation
Validate Semantic Versioning 2.0.0 version numbers (x.y.z-alpha.1 format)
semver-validatorDevelopment
Complete reference guide for HTML void elements (self-closing tags), SVG elements, and MathML elements
self-closing-html-tags