ToolHQ Blog
Guides, tutorials, and tips for getting the most out of free online tools. 185 articles.
185 articles — page 3 of 8
Your JWT Payload Is Not Encrypted. A 2015 Bug Let Attackers Change It by Setting the Algorithm to 'None'.
JWT payloads are Base64-encoded, not encrypted. Anyone with the token can read your user ID and role. A 2015 vulnerability let attackers bypass signature verification entirely.
400 Product Listings, 6-Second Load Times, and What Changing an Image Format Fixed
How converting PNG product images to WebP affects Core Web Vitals, Google rankings, and conversion rates. A practical breakdown for e-commerce sites.
Was the Investment Worth It? The ROI Formula Is Simple. The Answer Depends on What You Count.
ROI is net profit divided by cost. But what counts as profit and what counts as cost are decisions, not math. Here's why consistent definitions matter more than the formula.
The United States and Canada Are the Last Major Countries Still Using Letter-Size Paper. Here Is What Happens to Documents Crossing the Divide.
The US uses Letter, the world uses A4. That small size difference breaks documents constantly. Here is what resizing a PDF actually does and when you need it.
A Startup Chose Blue Because It Looked Professional. Here Is the Problem With That Logic.
The same reasoning that makes blue feel safe makes it the default for every competitor in your market. Here is what color research actually says about brand differentiation.
The Float-Clearing Hack Ran Production CSS for 15 Years. Flexbox Solved It in One Property.
Web developers used float hacks for column layouts for 15 years. Flexbox was specifically designed to solve those problems. Here is how it works and where it still trips developers.
Google Bought a Video Company in 2009. The Result Is Now the Web's Default Image Format.
WebP came from Google's 2009 acquisition of On2 Technologies and its VP8 video codec. Here's how video compression technology became the web's standard image format.
The Page Looked Fine. The Google Preview Was a Random Sentence from Paragraph 7.
Meta keywords were killed by Google in 2009. Meta descriptions, viewport tags, and Open Graph tags still matter. Here is the complete picture of what each tag does.
PDF Stores Instructions. PNG Stores Pixels. Here Is Why Resolution Is the Only Setting That Matters When Converting.
A PDF page does not exist as an image until a viewer renders it. When converting to PNG, the resolution you choose determines everything. Here is how to choose the right DPI.
Why Your WebP Files Open in Browsers but Nothing Else
WebP is everywhere on the web but incompatible with most photo software. Here's why the format gap exists and what to do when your images won't open.
Why Does a Web Page Look Perfect in Chrome But Break When You Print It to PDF? Here Is What the Browser Does Differently.
Browser print-to-PDF suppresses backgrounds, ignores page breaks, and reflows layouts. Here is what a dedicated HTML-to-PDF converter does that browsers cannot.
A Chinese Cryptographer Broke MD5, MD4, and Two Other Hash Functions in One Day in 2004. Here Is What Happened Next.
In August 2004, Xiaoyun Wang announced collision attacks on MD5 at CRYPTO 2004. Here is what hash collisions mean, which uses are still safe, and when SHA-256 is required.
JPG or PNG for Your iPhone Photos? The Answer Depends on What You Are Doing With Them.
PNG and JPG solve image storage differently. The right choice depends on your use case, especially if you need transparency or plan to edit the image repeatedly.
What Does a Broken Link Actually Cost? The Answer Has Three Parts.
Broken links waste crawl budget, interrupt authority flow, and degrade user experience. A JAMA study found 50% of cited links go dead within 5 years. Here is what to do.
A Well-Commented CSS File Is 30 to 50 Percent Larger Than It Needs to Be. Here Is What Gets Removed.
CSS comments, whitespace, and verbose values exist for humans and are ignored by browsers. Minifying removes them and can cut file size by up to 50 percent before gzip.
What Changes When a Spreadsheet Moves from CSV to Excel
A CSV file looks like a spreadsheet but isn't one yet. Here is exactly what changes when you convert CSV to Excel and when to choose each format.
An Excel File Is Not What It Looks Like. Here Is What CSV Export Strips Away.
Excel is a ZIP archive of XML files. CSV is plain text. Here is exactly what disappears when you export a spreadsheet to CSV and why that is often fine.
Making a GIF Is Easy. Making One That Actually Works Takes Different Decisions.
Creating a GIF from images is technically simple. Here is what determines whether the result communicates clearly: sequencing, frame duration, and file size trade-offs.
The Acre Was the Amount of Land One Man and Eight Oxen Could Plow in One Day. Edward I Made It Official in 1305.
The acre was not derived from mathematics — it was the daily output of a plow team. Edward I's 1305 statute fixed it, and the US still uses it today.
The Blank Page Problem Is Not About Writing. It Is About Structure.
Cognitive load theory explains why starting is hard. Here is what an outline actually does to your working memory, and why structure decisions are cheapest before drafting.
The BMR Formula Used for 65 Years Was Overestimating Calories. A 1990 Revision Fixed It.
Harris and Benedict published their BMR formula in 1919. It went unrevised for 65 years. The Mifflin-St Jeor revision in 1990 corrected a 5-8% systematic overestimate.
The US Navy Replaced Lab Tests With a Tape Measure in 1984. The Method Still Works.
Hodgdon and Beckett's 1984 Naval Health Research Center formula estimates body fat to within 3-4%. Here is how it compares to expensive lab methods.
Trimming a Video Is Not the Same as Cutting It. Here Are the Differences and Why They Matter.
Trimming removes from the edges. Cutting removes from the middle. Splitting creates two clips. Here is what each video editing operation actually does and when to use each.
Knots Come from a Rope Thrown Overboard in 1600. Aviation Still Uses Them Because Nobody Can Afford to Switch.
Knots were measured by counting knotted rope intervals on 16th-century ships. Here is why that unit survived into jet aviation, and why Mach 1 is not a fixed speed.