# CachePlex > 31 single-purpose web tools for developers, marketers and site owners: checking how a link previews when shared, converting images and documents, auditing on-page SEO, validating DNS and structured data, and building app store assets. Most run entirely in the browser, need no sign-up, and upload nothing to a server. Each tool page answers one specific question and states its own limits in plain language. Tools listed under a free tier have an optional paid upgrade; everything else is free, some with a small daily cap per IP address. - Tool index: https://www.cacheplex.com/tools - Guides and troubleshooting: https://www.cacheplex.com/blog ## Free tools - [SEO Analyzer](https://www.cacheplex.com/seo-analyzer/): Analyze any webpage for on-page SEO issues. Get an AI-powered score with actionable fixes to rank higher. - [WebP to JPG Converter](https://www.cacheplex.com/webp-to-jpg/): Convert WebP and AVIF images to JPG or PNG in your browser. Fixes images saved from websites that will not open in Photoshop, Word or Windows Photos. - [Email Deliverability Checker](https://www.cacheplex.com/email-deliverability-checker/): Find out why your emails go to spam. Checks SPF, DKIM, DMARC, MX and blacklists, and tells you the exact DNS record to fix. - [UTM Generator](https://www.cacheplex.com/utm-generator/): Easily add campaign parameters to URLs so you can measure Custom Campaigns in Google Analytics 4. - [AI Text Detector](https://www.cacheplex.com/ai-detector/): Instantly detect whether text was written by AI or a human, with confidence scores and detailed signal analysis. - [Readability Checker](https://www.cacheplex.com/readability-checker/): Measure content readability with Flesch Reading Ease and Flesch-Kincaid Grade Level scores. No word limits. - [Favicon Generator](https://www.cacheplex.com/favicon-generator/): Upload any image and generate ICO, PNG and WebP favicons in every size. Works with all browsers and devices. - [QR Generator](https://www.cacheplex.com/qr-generator/): Create QR codes for URLs, WiFi, vCards, email, SMS and more. Custom colors, download as high-res PNG instantly. - [App Icons Generator](https://www.cacheplex.com/app-icons-generator/): Generate all required iOS & Android app icon sizes from a single image. Download a ready-to-use ZIP in seconds. - [SVG to PNG Converter](https://www.cacheplex.com/svg-to-png/): Convert SVG to pixel-perfect PNG at any size, rendered by your own browser for correct gradients, fonts and transparency. - [JPG to PDF](https://www.cacheplex.com/jpg-to-pdf/): Combine JPG, PNG and other images into one PDF. Reorder and rotate pages, pick A4 or Letter, all in your browser. - [PDF to JPG](https://www.cacheplex.com/pdf-to-jpg/): Save PDF pages as JPG or PNG images at 72, 150 or 300 DPI. Convert every page or a range, download a ZIP. - [Image Resizer](https://www.cacheplex.com/image-resizer/): Resize images by pixels, percentage or target file size like 50 KB. Batch resize with presets and download a ZIP. - [Background Remover](https://www.cacheplex.com/background-remover/): Remove the background from a photo with AI that runs in your browser. Transparent PNG or any colour, with a touch-up brush. - [HEIC to JPG Converter](https://www.cacheplex.com/heic-to-jpg/): Convert multiple iPhone HEIC photos to JPG at once. Converted in your browser, downloaded one by one or as a single ZIP. - [Share Preview Checker](https://www.cacheplex.com/share-preview-checker/): See how a link looks on WhatsApp, Facebook, LinkedIn and X. Test the Open Graph image and fix missing or broken tags. - [Robots.txt Checker](https://www.cacheplex.com/robots-checker/): Fetch and analyze any site's robots.txt file. Get a full report on directives, sitemaps, issues and fixes. - [SSL Checker](https://www.cacheplex.com/ssl-checker/): Verify any domain's SSL certificate. Check validity, expiry, issuer, security grade (A+ to F) and chain details. - [Robots.txt Generator](https://www.cacheplex.com/robots-txt-generator/): Build a clean, valid robots.txt with the right directives, crawl rules and sitemap references in minutes. - [Sitemap Validator](https://www.cacheplex.com/sitemap-validator/): Validate any XML sitemap for structure, errors and URL issues so search engines can crawl your site cleanly. - [JSON Validator](https://www.cacheplex.com/json-validator/): Validate, format and beautify JSON instantly. Catch syntax errors with clear line-by-line messages. - [JSON Formatter](https://www.cacheplex.com/json-formatter/): Format, validate, minify, and explore your JSON data with advanced syntax highlighting and instant error reporting. - [HTML Minifier](https://www.cacheplex.com/html-minifier/): Compress and minify HTML — remove comments and whitespace to cut file size and speed up your pages. - [CSS Minifier](https://www.cacheplex.com/css-minifier/): Minify CSS to shrink stylesheet size and improve load times, without changing how your site looks. - [Schema Checker](https://www.cacheplex.com/schema-checker/): Enter any URL to find and validate its JSON-LD structured data. See every schema type and catch invalid markup instantly. - [WebP Converter](https://www.cacheplex.com/webp-converter/): Convert bulk PNG and JPEG images to next-gen WebP format instantly to boost your Core Web Vitals. - [Image Compressor](https://www.cacheplex.com/image-compressor/): Smart image compression with a visual before/after slider. Shrink file sizes drastically without losing quality. ## Link preview checkers by app - [Discord Embed Checker](https://www.cacheplex.com/share-preview-checker/discord/): Check how a link will embed in Discord before you post it. See the title, description, image and colour Discord shows, and find out why an embed is missing. - [Slack Link Preview Checker](https://www.cacheplex.com/share-preview-checker/slack/): See how a link will unfurl in Slack before you share it. Check the title, description, image, icon and extra fields Slack shows, and why an unfurl is missing. - [Telegram Link Preview Checker](https://www.cacheplex.com/share-preview-checker/telegram/): Check the link preview Telegram will show for a URL: title, description, image and site name. Find out why a preview is missing and how to update an old one. - [iMessage Link Preview Checker](https://www.cacheplex.com/share-preview-checker/imessage/): Preview how a link will look in Apple Messages before you send it. Check the title, image and icon iMessage uses and find out why a rich link is not showing. - [LinkedIn Post Preview Checker](https://www.cacheplex.com/share-preview-checker/linkedin/): See how a link will look when shared in a LinkedIn post. Check the title and image LinkedIn uses, find out why the image is missing, and clear an old preview. - [Facebook Link Preview Checker](https://www.cacheplex.com/share-preview-checker/facebook/): Check how a link will look when shared on Facebook and Messenger: the title, description and image from your Open Graph tags, with fixes for missing images. - [X (Twitter) Card Checker](https://www.cacheplex.com/share-preview-checker/x-twitter/): X removed the preview from its Card Validator. Check your Twitter Card and Open Graph tags here, see the card X will show, and find out why it is missing. - [Site-Wide Share Preview Scan](https://www.cacheplex.com/share-preview-checker/site-scan/): Reads a sitemap and checks the Open Graph tags and share image of every page at once. First 5 pages free. ## Tools with a free tier and a paid upgrade - [PostPlex — Social Post Studio](https://www.cacheplex.com/postplex/): Design social posts from professionally built templates. Edit the text right on the canvas, pick your size, and download a ready-to-upload PNG. - [App Store Screenshot Generator](https://www.cacheplex.com/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. - [AI Humanizer](https://www.cacheplex.com/ai-humanizer/): Transform AI-generated text into natural, human-sounding content with a warmer, more human tone. Free tier available. - [Meta Tag Generator](https://www.cacheplex.com/seo-meta-generator/): Generate SEO-optimized meta titles and descriptions from plain page details. One page free, or bulk from a CSV. ## Guides Written to answer a specific symptom rather than to cover a topic broadly. ### AI Tools - [How to Make ChatGPT Sound More Human](https://www.cacheplex.com/blog/how-to-make-chatgpt-sound-more-human): ChatGPT writes fast — but it doesn't write like you. Here's a practical guide to getting output that sounds like a real person, not a language model trying too hard. - [How to Humanize ChatGPT Content](https://www.cacheplex.com/blog/how-to-humanize-chatgpt-content): AI-generated content fails when it sounds AI-generated. Here's a practical, step-by-step guide to humanizing ChatGPT output — so it reads naturally, ranks better, and… - [How to Make AI-Generated Content Read Like a Human Wrote It](https://www.cacheplex.com/blog/how-to-make-ai-generated-content-read-like-human): AI content is efficient. But efficient doesn't mean effective. Here's a complete guide to transforming machine-generated text into writing that feels genuinely… - [How to Detect AI-Generated Content (Free Tool Included)](https://www.cacheplex.com/blog/how-to-detect-ai-generated-content-free-tool): AI-written content is everywhere — but how do you actually tell? Learn how AI detectors work, what signals they look for, and how to check any text for free in seconds. ### App Development - [App Store Connect Won’t Accept Your Screenshots? Every Reason It Happens](https://www.cacheplex.com/blog/app-store-connect-screenshot-upload-errors): Screenshot dimensions rejected, wrong display size tab, missing iPad set, transparency and colour space. Every cause of a failed App Store screenshot upload, and the fix… - [How to Create App Icons for iOS and Android (Free Tool)](https://www.cacheplex.com/blog/how-to-create-app-icons-ios-android-free): Learn how to generate all required app icon sizes for iOS and Android from a single image. No design skills needed — just upload and download your ZIP in seconds. ### App Marketing - [What to Put on Your App Store Screenshots (and What to Leave Off)](https://www.cacheplex.com/blog/what-to-put-on-app-store-screenshots): Captions that convert, how many screenshots to use, device frames, the Play feature graphic, and the things that get a listing rejected. A practical guide for indie… ### Content Creation - [How to Make AI Text Sound Human, Natural, and Undetectable](https://www.cacheplex.com/blog/how-to-make-ai-text-sound-human): AI writing often sounds robotic, repetitive, and lacks emotion. Here is a practical guide to humanizing AI-generated content so it engages readers and bypasses detectors. ### Content Writing - [Readability Scores Explained: Flesch, FK Grade, and Why They Matter for SEO](https://www.cacheplex.com/blog/readability-score-guide-flesch-fk-grade-explained): A Flesch Reading Ease of 72. A Flesch-Kincaid Grade of 8. What do those numbers actually mean — and how do they affect your rankings and conversions? Here's the complete… ### Digital Tools - [How to Create QR Codes for Free: A Complete Guide for Businesses](https://www.cacheplex.com/blog/how-to-create-qr-codes-free-complete-guide): QR codes are one of the most powerful — and underused — tools in digital marketing. Here's everything you need to know, plus a free generator to create yours instantly. ### Email Deliverability - [Why Are My Emails Going to Spam? The Six Real Causes (and How to Fix Each)](https://www.cacheplex.com/blog/why-are-my-emails-going-to-spam): Emails landing in junk is almost never your subject line. It is usually SPF, DKIM or DMARC — including the 10-lookup limit that breaks SPF silently. Here is how to find… ### Image Resizing - [How to Resize an Image to 50KB, 100KB or Any File Size](https://www.cacheplex.com/blog/how-to-resize-image-to-specific-kb): Shrink a photo under an upload limit like 20 KB, 50 KB or 100 KB without making it blurry. The difference between KB, pixels and DPI, with tested results. ### Marketing Analytics - [How to Create UTM Tracking Links for GA4](https://www.cacheplex.com/blog/how-to-create-utm-tracking-links-for-ga4): Build clean UTM tracking links for Google Analytics 4. See source, medium, campaign, and content examples plus a naming system that prevents messy reports. ### Off-Page SEO - [How to Find Competitor Backlinks and Steal Their SEO Strategy](https://www.cacheplex.com/blog/how-to-find-competitor-backlinks): Your competitors are ranking above you because of their backlink profile. Learn how to check competitor backlinks and uncover easy link-building opportunities. ### On-Page SEO - [How to Write SEO Meta Tags for Hundreds of Pages Fast](https://www.cacheplex.com/blog/how-to-write-seo-meta-tags-fast): Writing unique meta titles and descriptions for a large website is a nightmare. Discover how to bulk generate perfectly optimized SEO meta tags in minutes. - [Title Tag Optimization: The Complete Guide for 2025](https://www.cacheplex.com/blog/title-tag-optimization-complete-guide): The title tag remains the most influential on-page SEO element you can control. This guide covers length, format, keyword placement, and every edge case — with real… - [How to Write Meta Descriptions That Actually Get Clicked](https://www.cacheplex.com/blog/how-to-write-meta-descriptions-that-get-clicked): Your meta description is your organic ad copy. Here's the formula for writing descriptions that drive clicks, improve CTR, and bring more qualified traffic to your pages. - [10 On-Page SEO Mistakes That Are Silently Killing Your Rankings](https://www.cacheplex.com/blog/on-page-seo-mistakes-killing-your-rankings): You could have brilliant content and still rank on page 3. These ten fixable on-page errors are the most common reason well-written pages never reach page one. ### PDF Tools - [How to Convert JPG to PDF (and Combine Multiple Photos Into One PDF)](https://www.cacheplex.com/blog/how-to-convert-jpg-to-pdf): Convert JPG to PDF and combine several photos into one file. Page order, sideways photos, A4 vs Letter, and how to shrink a PDF that is too big to upload. ### Photo Conversion - [Why Can't I Open a WebP File? (And How to Convert It Properly)](https://www.cacheplex.com/blog/why-cant-i-open-a-webp-file): Photoshop rejects it, Word will not insert it, and the print shop says no. Why WebP and AVIF files refuse to open outside your browser, why renaming them makes things… - [Why Won’t HEIC Photos Open on Windows? Three Fixes That Actually Work](https://www.cacheplex.com/blog/heic-photos-wont-open-on-windows): Windows cannot read iPhone HEIC photos out of the box. Convert them, install the codec, or stop the iPhone making them — with the trade-offs of each. - [How to Convert Multiple iPhone HEIC Photos to JPG at Once](https://www.cacheplex.com/blog/convert-multiple-heic-photos-to-jpg): Batch convert iPhone HEIC photos to JPG in minutes. Why HEIC causes compatibility problems, which quality to choose, what happens to file size and metadata, and how to… ### Photo Editing - [How to Remove the Background From a Photo for Free (and Get Clean Edges)](https://www.cacheplex.com/blog/how-to-remove-background-from-photo-free): Remove a photo background for free, then fix the edges: halos, shadows and missing parts. When to use a transparent PNG or a white background. ### SEO - [How to Write Meta Titles and Descriptions in Bulk (Without Losing a Weekend)](https://www.cacheplex.com/blog/how-to-write-meta-tags-in-bulk): Writing meta tags for one page is easy. Writing them for two hundred is a slog. Here is a faster, saner way to generate optimized titles and descriptions in bulk. - [How to Fix Duplicate Meta Descriptions (and Actually Keep Them Unique)](https://www.cacheplex.com/blog/how-to-fix-duplicate-meta-descriptions): Duplicate meta descriptions are one of the most common SEO warnings, and one of the easiest to fix. Here is how to find them, fix them, and stop them coming back. ### Social Media - [What Size Should Social Media Post Images Be? A Straight Answer](https://www.cacheplex.com/blog/what-size-should-social-media-post-images-be): Forget memorising a pixel table for every platform. There are really only four shapes that matter, and this guide covers what each one is for, what gets cropped, and how… - [How to Make Social Media Graphics When You Are Not a Designer](https://www.cacheplex.com/blog/how-to-make-social-media-graphics-without-design-skills): You do not have bad taste — you have too many decisions. Here is a practical workflow for making social posts that look deliberate, without learning design software or… - [How to Make Quote Graphics for Instagram Free (No Photoshop Needed)](https://www.cacheplex.com/blog/how-to-make-quote-graphics-for-instagram-free): Quote posts are the easiest graphics to make and the easiest to make badly. Here is how to pick a quote that works visually, set it so it reads at thumbnail size, and… ### Social Sharing - [Link Preview Showing the Wrong Image? How to Clear the Cache on Every Platform](https://www.cacheplex.com/blog/link-preview-showing-wrong-image): You changed the og:image and the old one still appears. That is caching, not a tagging problem. Here is how to force a refresh on Facebook, LinkedIn, X, Slack and… - [Why Is My WhatsApp Link Preview Image Not Showing? How to Check and Fix It](https://www.cacheplex.com/blog/whatsapp-link-preview-image-not-showing): WhatsApp link preview missing its image, showing the wrong one, or stuck on an old version? Follow this step-by-step check of your Open Graph tags, share image and… ### Technical SEO - [Search Console Says “Couldn’t Fetch” Your Sitemap: What Each Error Means](https://www.cacheplex.com/blog/search-console-couldnt-fetch-sitemap): Couldn’t fetch, could not be read, general HTTP error, 0 discovered URLs — each means something different. What causes each one, and how to fix it. - [How to Run an SEO Audit on Your Own Site in Under an Hour](https://www.cacheplex.com/blog/how-to-run-seo-audit-yourself): Most audits fail because they start in the wrong place. Work in dependency order — crawlable, indexed, on-page, technical, content — and an hour is enough. - [How to Check If a Website Has Schema Markup (Free, No Code Needed)](https://www.cacheplex.com/blog/how-to-check-if-a-website-has-schema-markup): You do not need to read source code to see a page's structured data. Here is how to check any URL for schema markup in seconds, read the results, and act on what you… - [What Is robots.txt and How to Check It for SEO Issues (Free Tool)](https://www.cacheplex.com/blog/what-is-robots-txt-and-how-to-check-it): Your robots.txt file controls which pages search engines can crawl — one wrong line can accidentally block your entire site. Here's everything you need to know, plus a… - [How to Check SSL Certificate Expiry and Security Grade](https://www.cacheplex.com/blog/how-to-check-ssl-certificate-website-security-grade): Check an SSL certificate’s expiry, hostname coverage, SANs, issuer, key, signature, and chain—then diagnose common browser warnings step by step. - [Structured Data Explained: How to Unlock Rich Snippets in Google Search](https://www.cacheplex.com/blog/structured-data-guide-rich-snippets-2025): Rich snippets — star ratings, FAQs, breadcrumbs, recipes — dramatically improve click-through rates. This guide explains Schema.org structured data, JSON-LD, and exactly… - [Why HTTPS Is No Longer Optional: The Impact on SEO and User Trust](https://www.cacheplex.com/blog/why-https-matters-for-seo-and-user-trust): HTTPS became a Google ranking signal in 2014. In 2025, a site without it triggers browser warnings, destroys conversion rates, and sends a negative trust signal no… ### Web Design - [How to Create a Favicon for Your Website (Free, No Design Skills Needed)](https://www.cacheplex.com/blog/how-to-create-favicon-for-website-free): That tiny icon in the browser tab is doing more for your brand than you think. Here's what a favicon is, why it matters, and how to create a complete favicon package… ### Web Security - [“Your Connection Is Not Private”: What It Means and How to Fix It](https://www.cacheplex.com/blog/your-connection-is-not-private-ssl-certificate-error): Expired certificate, name mismatch, broken chain or just a wrong clock? Read the error code, work out whose problem it is, and fix the one that actually applies. ### Web Tools - [What Free Tools Do You Actually Need to Run a Website? A Working Toolkit](https://www.cacheplex.com/blog/free-tools-you-need-to-run-a-website): A working toolkit organised by the questions that actually come up: links that preview wrongly, pages missing from Google, emails in spam, images that will not open… ### Website Performance - [How to Reduce Image File Size Without Losing Quality](https://www.cacheplex.com/blog/how-to-reduce-image-file-size-without-losing-quality-website): Reduce website image file sizes without visible quality loss. Learn when to resize, compress, or convert to WebP, plus the mistakes that make images blurry. ## Optional - [About CachePlex](https://www.cacheplex.com/about): Who builds these tools and why. - [Contact](https://www.cacheplex.com/contact): Report a bug or suggest a tool. - [Privacy policy](https://www.cacheplex.com/privacy): What is stored, for how long, and what never leaves your browser. - [Terms of service](https://www.cacheplex.com/terms): Usage terms for the free and paid tiers.