Jawad Hassan

Tool Builder & Display Researcher

🛠️ 3 active tool sites 🔍 Sources: MDN, W3C, manufacturer specs 🔒 Privacy-first methodology 📅 Active since 2023

I build free browser tools that solve specific, verifiable problems. screenres.app is my display diagnostics project — a privacy-first toolkit that runs entirely client-side, used by developers, designers, and QA engineers to inspect screen resolution, pixel density, DPR, viewport dimensions, and display uniformity without installing software or sending data anywhere.

My background is in building accurate, methodology-transparent tools across several domains. Every diagnostic on this site is grounded in published technical specifications: the W3C Screen API, the Visual Viewport API spec, and manufacturer display datasheets. When browser APIs disagree with hardware specs — as they do on many Samsung and high-DPI Android devices — I document the discrepancy rather than hide it.

I'm not a hardware engineer and I don't claim to be. What I do claim: I read the specs, I test on real devices, I cite sources, and I correct errors when they're reported. Every calculator and guide on this site follows the same standard — see the testing methodology for the full process.

I also run CalnConvert (calculators and converters) and DogFoodCostCalc (nutrition-based dog feeding cost calculator built on AAFCO guidelines) — both built on the same privacy-first, source-linked philosophy.

Areas of focus

Display diagnostics

Screen resolution, DPR, PPI, viewport APIs, color depth, pixel uniformity testing.

Browser APIs

Screen API, Visual Viewport API, Window Management API, devicePixelRatio behavior across engines.

Responsive design tooling

CSS breakpoints, media queries, viewport units, cross-device testing methodology.

Privacy-first architecture

Client-side-only computation, consent-gated analytics, GDPR-compliant tool design.

Editorial responsibility

Source requirement: Every factual claim links to a primary source — W3C specs, MDN documentation, StatCounter data, or manufacturer datasheets. No claims sourced from secondary SEO articles.
Device testing: Core APIs are verified on real devices across Chrome, Safari, Firefox, and Samsung Internet. Known browser quirks (e.g. Samsung Android returning scroll height from window.innerHeight) are documented explicitly.
Corrections policy: Errors are corrected within 48 hours of being reported. No silent edits — corrections are noted in the changelog. Report via the contact page.
Privacy commitment: No display data is sent to servers. All diagnostics compute locally. See the full accuracy and privacy statement.

Full policies: Testing methodology · Editorial standards · Privacy statement

Tools built at screenres.app

All tools run client-side. No server calls. No data collection.

Screen Resolution Checker — Live detection: resolution, viewport, DPR, aspect ratio, color depth.
Viewport Size Checker — CSS viewport dimensions, updates live on resize.
DPR Checker — Device pixel ratio detection and density tier classification.
PPI Calculator — Pixels per inch from resolution and diagonal size.
Dead Pixel Test — Full-screen color panels for detecting defective pixels.
Monitor Ghosting Test — Motion trail detection for high-refresh displays.
Device Resolution Database — Resolution, CSS viewport, DPR, PPI for 70+ devices.
All display tools →

Other projects

CalnConvert — Free calculators and unit converters. Finance, health, and everyday math.
DogFoodCostCalc — Nutrition-based dog feeding cost calculator built on AAFCO guidelines.
Malkeeyat — Pakistani real estate property services.

Corrections and contact

Found an error in a tool, a stale spec, or a wrong number? Use the contact page to submit a correction. I review all reports and respond within 48 hours.

Last updated: June 2026