Curated picks
Tools
Open a card for a full guide and a browser-only tool — no uploads. Details and external picks are below.
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In-browser tools
Utilities that run locally in your browser — use the topic filter above to narrow the list.
- Base64 encode & decode
Turn text into Base64 and back — UTF-8 safe, in your tab.
In-browser SecurityOpen - HTML entity encode & decode
Escape text for HTML or decode common entities — client-side only.
In-browser SecuritySEOOpen - JSON format & minify
Validate, pretty-print, or compress JSON for configs and APIs.
In-browser PerformanceSecurityOpen - JWT decoder
Inspect header and payload JSON — signature is not verified here.
In-browser SecurityOpen - Meta description length
Count characters and aim for a snippet-friendly range.
In-browser SEOOpen - SHA-256 hash
Fingerprint arbitrary text with SHA-256 — no server round trip.
In-browser SecurityOpen - Unix time converter
Parse ISO strings or Unix seconds/ms into local time and UTC.
In-browser PerformanceOpen - URL encode & decode
Percent-encode query values or decode escaped strings.
In-browser SEOOpen - URL slug generator
Turn titles into clean path segments for blogs and static routes.
In-browser SEOOpen
Hand-picked from the web
Editorial bookmarks for audits and research — each opens in a new tab at the provider.
Editor’s pick
@cometweb/carbon-badgeLightweight website carbon footprint badge for your pages — npm package for teams and static sites.
EcologyExternal- Accessibility Insights
Fast checks and guided assessments from Microsoft.
AccessibilityExternal - axe DevTools
Browser extension and APIs used in many CI pipelines.
AccessibilityExternal - Bing URL Inspection
See how Bing crawls and indexes a URL.
SEOExternal - Bundlephobia
Check npm package size and dependency cost before you install.
PerformanceExternal - Can I use
Browser support tables for HTML, CSS, and JavaScript features.
PerformanceSEOExternal - Chrome DevTools
Performance panel, coverage, and memory tooling in the browser.
PerformanceExternal - CSP Evaluator
Paste a Content-Security-Policy and spot risky directives.
SecurityExternal - Ecograder
Sustainability score with actionable recommendations.
EcologyExternal
Further down you will find hand-picked third-party tools we use in audits (each opens in a new tab), plus links to our topic hubs and the rest of the site.
For deeper reading, jump into our topic hubs. Everything here opens in a new tab on the provider’s site.
Explore our Performance, Ecology, Accessibility, Security, and SEO hubs for deeper reading.