Tools starting with H

13 available now, 2 planned, 2 not possible in a browser.

Available now

Heading Analyzer

Check a page's heading outline for skipped levels, duplicates and missing h1.

Heart Rate Zone Calculator

Work out training heart rate zones from age and resting heart rate.

HEX to HSL Converter

Convert a hex colour to HSL, plus RGB, HSV and CMYK.

HEX to RGB Converter

Convert colours between HEX, RGB and HSL with a live preview and copyable CSS values.

Hex Viewer

View any file as a hex dump with its text column, and search for bytes or text.

HMAC Generator

Sign a message with a secret key using HMAC-SHA256 and related algorithms.

Hreflang Generator

Generate hreflang link tags for multilingual and regional versions of a page.

HSL to RGB Converter

Convert HSL values to RGB and hex, with HSV and CMYK alongside.

HTML Entity Encoder & Decoder

Escape text for safe use in HTML, or decode entities back into readable characters.

HTML Formatter & Minifier

Indent messy or minified HTML so it can be read, or strip it back down to one line.

HTML Live Editor

Write HTML and see it render as you type, in a sandboxed frame.

HTML to Text

Strip HTML to readable plain text, keeping paragraphs, list markers and link URLs.

HTTP Status Code Reference

Look up any HTTP status code, what it means and what it usually indicates in practice.

HEIC to JPG — No browser except Safari decodes HEIC, so the page would fail for most visitors on the file it names.
HEIC to PNG — The same missing HEIC decoder; the output format does not change what the browser cannot read.