Built for Creators. Engineered for Privacy.
Calkora provides 16 precision-engineered, free marketing and developer tools. Every single conversion, canvas render, and diagnostic check runs 100% inside your browser with zero server uploads.
Eliminating the Pain of Creative Asset Rejections
Every day, app developers submit icons to Google Play only to be rejected over a 1-pixel dimension mismatch. Digital marketing agencies spend thousands on Google Ads campaigns, only to have responsive display ads stalled by non-compliant aspect ratios. YouTubers upload thumbnail files that exceed the strict 2MB limit.
Existing online tools either demand paid subscriptions, plaster watermarks over your work, or upload your sensitive pre-launch marketing creative to remote cloud servers where confidential graphics risk exposure.
We built Calkora to change that. By utilizing modern WebAssembly, HTML5 Canvas 2D contexts, and client-side JavaScript, Calkora delivers instantaneous, zero-upload verification and conversion tools directly to your browser.
100% Client-Side Privacy
Your images, text, and metadata never leave your computer or phone. No cloud storage, no server caching, and zero tracking of your proprietary files.
Zero Latency Processing
Because computation runs on your device's CPU and GPU, resizing and validation occur instantaneously without waiting for network file uploads.
Aligned with Platform Standards
Every diagnostic threshold is calibrated against official guidelines from Google Ads, Google Play Console, YouTube, and schema.org.
The Complete Calkora Toolkit (16 Free Tools)
Explore our comprehensive suite designed for developers, growth marketers, and digital creators.
App Store Optimization
Play Store Asset Checker
Instant pre-flight diagnostic for icons, screenshots, and feature graphics against Google Play Console criteria.
Launch Tool โPlay Store Asset Converter
Batch generate all 6 Android icon densities (mdpi to xxxhdpi) plus Play Store 512ร512 master icons.
Launch Tool โPlay Store Listing Checker
Validate app title (30 chars), short description (80 chars), and full description (4000 chars) with policy warnings.
Launch Tool โAd Platforms & Asset Verification
Smart Image Resizer & WebP
High-performance canvas resizer with aspect locking, padding/letterboxing, and WebP compression.
Launch Tool โGoogle Ads Image Checker
Verify 1.91:1 landscape, 1:1 square, and 4:5 portrait formats for Google Display & Performance Max campaigns.
Launch Tool โGoogle Ads Text Checker
Validate responsive search ad 30-char headlines and 90-char descriptions with realistic Google SERP mockups.
Launch Tool โBulk Creative Asset Checker
Drag and drop up to 20 images at once to validate specifications simultaneously and download a compliant ZIP bundle.
Launch Tool โSocial, Growth & Creator Tools
UTM URL Builder
Build sanitized GA4 campaign URLs with one-click presets, parameter normalization, and CSV export.
Launch Tool โWhatsApp Link & QR Generator
Generate click-to-chat links with prefilled messages and download high-resolution vector QR codes.
Launch Tool โSocial Media Post Preview
Simulate live feed appearance across ๐ (Twitter), LinkedIn, and Instagram with character counters.
Launch Tool โYouTube Thumbnail Checker
Verify 1280ร720 resolution, 16:9 ratio, and under 2MB weight with a live YouTube video preview mockup.
Launch Tool โSEO Meta Preview
Test meta titles and descriptions against Google search snippet limits on desktop and mobile viewports.
Launch Tool โOpen Graph Generator
Craft Open Graph and Twitter Card tags with real-time Facebook, Twitter, and LinkedIn card previews.
Launch Tool โSchema Markup Generator
Generate valid JSON-LD structured data for Articles, Products, Organizations, FAQs, and Local Businesses.
Launch Tool โYouTube Thumbnail Creator
One-click transform any image into compliant 1280ร720 or 1920ร1080 16:9 thumbnails under 2MB with smart crops.
Launch Tool โSmart Video Compressor
Zero-upload in-browser video compressor with Discord 8MB auto-limit, WhatsApp, and email presets.
Launch Tool โEditorial & Technical Accuracy Standards
Our team continually monitors official policy documentation to ensure our diagnostic rules remain 100% accurate.
Google Play Console Compliance
We maintain strict fidelity to Google Play's icon specifications (512ร512 PNG, 32-bit color, no alpha transparency, max 1024KB) and feature graphics (1024ร500 JPG/PNG).
Google Ads Display & PMax Guidelines
Our checkers validate 1.91:1 landscape (minimum 600ร314, recommended 1200ร628), 1:1 square (minimum 300ร300, recommended 1200ร1200), and 4:5 portrait formats with exact aspect ratio tolerances.
YouTube Creator Specifications
We enforce YouTube's recommended 1280ร720 (minimum 640px width) 16:9 ratio and 2MB file size ceiling to ensure crisp video thumbnail rendering across all devices.
Schema.org & Search Engine Standards
Our JSON-LD structured data generators strictly adhere to schema.org syntax and Google Search Central rich results guidelines.
Publisher Transparency & Contact
Calkora is an independent digital utility platform. We are committed to transparency, user privacy, and continuous improvement. We welcome feedback, error reports, and feature recommendations.