Awesome Free Web Tools

A curated list of free online tools for websites, images, PDFs, SEO and link previews, each built to answer one specific question fast. They run in the browser, most of them need no sign-up, and the image and PDF converters process your files on your own device.

Every tool in this list is part of CachePlex, a free toolkit for website owners, marketers, developers and anyone who has ever asked “why won’t this photo open?” or “why does my link show the wrong image on WhatsApp?”. Each entry says what the tool does, the questions it answers, and links straight to it.

Quick links: All tools · Troubleshooting guides · Which free tools do you actually need? · llms.txt

Contents

Social Share Preview Checker

See exactly how a link will look when it is shared on WhatsApp, Facebook, LinkedIn, X (Twitter), Discord, Slack, Telegram and iMessage, before you share it. The checker reads the page the way link-preview crawlers do (raw HTML, no JavaScript), lists every Open Graph and Twitter Card tag, downloads the share image to confirm it really loads, and explains each problem in plain English with the fix. It also suggests a complete, copy-ready set of og: tags.

Site-Wide Share Preview Scan

Checks the share preview of every page in your sitemap at once, instead of one URL at a time. It finds the problems a single check cannot show: pages with no share image, images that fail to load for crawlers, one default image on every page, and duplicate titles that make different pages look identical when shared. The homepage is checked first because it is the page shared most.

Every app reads the same Open Graph tags but has its own rules for images, caching and layout. Each of these pages opens the checker on that app’s preview and explains how to fix and refresh it there:

PostPlex: Social Post Studio

Design social media posts from professionally built templates without design software. Edit the text directly on the canvas, choose the post size (square, portrait, story or landscape link image), and download a ready-to-upload PNG. Useful for quote posts, announcements and 1200 × 630 Open Graph share images.

SEO and Site Health

SEO Analyzer

Analyse any web page for on-page SEO problems and get a score with prioritised fixes: title and meta description, headings, images and alt text, links, and other on-page factors, with AI-assisted recommendations.

Schema Markup Checker

Enter any URL to find and validate its structured data: JSON-LD, Microdata and RDFa. See every schema type on the page (Product, Article, FAQPage, Organization and more) and catch invalid markup that stops rich results from appearing in search.

Meta Tag Generator

Generate SEO-optimised meta titles and meta descriptions from plain page details. Do one page for free, or generate tags for many pages at once from a CSV.

Robots.txt Checker

Fetch and analyse any site’s robots.txt. Get a full report on its directives, Sitemap lines, issues and suggested fixes.

Robots.txt Generator

Build a clean, valid robots.txt with a guided builder: crawl rules per user agent, blocked paths and sitemap references, ready to copy to your site’s root.

Sitemap Validator

Validate any XML sitemap or sitemap index for structure, errors and URL problems, so search engines can crawl your site cleanly. Finds your sitemap through robots.txt if you only know the domain.

SSL Certificate Checker

Check any domain’s SSL/TLS certificate: validity, expiry date, issuer, certificate chain and an A+ to F security grade.

Email Deliverability Checker

Find out why your emails go to spam. Checks a domain’s SPF, DKIM, DMARC and MX records and blacklist status, including SPF’s 10-DNS-lookup limit that breaks silently, then tells you the exact DNS record to fix.

Add campaign parameters (utm_source, utm_medium, utm_campaign, utm_term, utm_content) to any URL so you can measure campaigns in Google Analytics 4.

Image Converters and Editors

HEIC to JPG Converter

Convert multiple iPhone HEIC photos to JPG at once. Conversion happens in your browser, so the photos are never uploaded. Download them one by one or as a single ZIP.

WebP and AVIF to JPG Converter

Convert WebP and AVIF images to JPG or PNG in your browser. Fixes images saved from websites that will not open in Photoshop, Word, Windows Photos or a print shop’s software. Batch conversion with ZIP download.

WebP Converter (JPG/PNG to WebP)

Convert PNG and JPEG images to WebP in bulk to cut page weight and improve Core Web Vitals. Runs privately in your browser, with a ZIP download.

SVG to PNG Converter

Convert SVG to a pixel-perfect PNG at any size. The SVG is rendered by your own browser, so gradients, fonts and transparency come out correctly.

Image Compressor

Shrink image file sizes with a visual before/after slider, so you can see the quality you keep while the size drops.

Image Resizer

Resize images by pixels, by percentage, or to a target file size such as 20 KB, 50 KB or 100 KB for upload forms. Batch resize with presets and download a ZIP.

Background Remover

Remove the background from a photo with an AI model that runs in your browser. Export a transparent PNG or put the subject on any colour, then clean up edges with a touch-up brush.

PDF Tools

JPG to PDF Converter

Combine JPG, PNG and other images into one PDF. Reorder and rotate pages, choose A4 or Letter, and keep the original image quality, all in your browser.

PDF to JPG Converter

Save PDF pages as JPG or PNG images at 72, 150 or 300 DPI. Convert every page or a range of pages and download them as a ZIP.

Icons, QR Codes and App Store Assets

Favicon Generator

Upload any image and generate a complete favicon set (ICO, PNG and WebP in every size browsers and devices ask for) as a ZIP.

App Icons Generator

Generate every required iOS and Android app icon size from a single image and download a ready-to-use ZIP.

QR Code Generator

Create QR codes for URLs, Wi-Fi networks, vCards, email, SMS and more, with custom colours, and download a high-resolution PNG.

App Store Screenshot Generator

Turn raw app screenshots into a store-ready set: device frames, headlines, and a ZIP at every exact size the App Store and Google Play require, including the Play feature graphic.

AI Writing and Content

AI Text Detector

Check whether a piece of text was likely written by AI or by a person, with a confidence score and a breakdown of the signals behind it.

AI Humanizer

Rewrite AI-generated text so it reads naturally, with a warmer and more human tone.

Readability Checker

Score any text with Flesch Reading Ease and Flesch-Kincaid Grade Level,, with no word limit.

Developer Tools

JSON Formatter

Format, validate, minify and explore JSON with syntax highlighting and instant error reporting.

JSON Validator

Validate and beautify JSON and catch syntax errors with clear, line-by-line messages.

HTML Minifier

Minify HTML by removing comments and unnecessary whitespace to cut file size and speed up pages, with before/after size stats.

CSS Minifier

Minify CSS to shrink stylesheets and improve load times without changing how the site looks.

Troubleshooting Guides

Step-by-step answers to specific problems, each linking to the tool that fixes it.

Start here: What Free Tools Do You Actually Need to Run a Website? A Working Toolkit, which walks through this list by the problem each tool solves.

Link previews and social media

Photos and images

SEO and websites

Email

Apps, icons and QR codes

Writing and AI content

Which tool do I need?

I want to… Use
See how my link looks on WhatsApp, Facebook, LinkedIn or X Share Preview Checker
Check every page’s share image at once Site-Wide Share Preview Scan
Fix a Discord embed or Slack unfurl Discord · Slack
Open an iPhone photo on Windows HEIC to JPG
Open a WebP image in Photoshop or Word WebP to JPG
Get a photo under 50 KB for a form Image Resizer
Make a transparent PNG Background Remover
Put several photos into one PDF JPG to PDF
Stop my emails going to spam Email Deliverability Checker
Find out why a page is not ranking SEO Analyzer
Check my structured data Schema Checker
Fix a sitemap Search Console cannot read Sitemap Validator
Make a favicon or app icons Favicon Generator · App Icons
Make a QR code QR Generator

About this list

These tools are built and maintained by CachePlex. Most are free with no account; a few have an optional paid tier for heavy use, which is marked on each entry. Image and PDF converters process files in your browser, so your files are not uploaded.

Found a broken link or have a tool idea? Open an issue or contact us.

License

CC0

The text of this list is released under CC0 1.0. The tools themselves are services of CachePlex.