ToolHQ Blog
Guides, tutorials, and tips for getting the most out of free online tools. 185 articles.
185 articles — page 2 of 8
The Protocol That Ran the Internet for 28 Years Without Being a Standard
The robots.txt Robots Exclusion Protocol ran every major crawler from 1994 until the IETF finally published RFC 9309 in 2022. Here is what changed and what stayed ambiguous.
You Are Probably Overestimating How Much You Need to Save Each Month
Dividing your savings goal by months gives the wrong answer once interest is in the picture. Here is how compound interest reduces what you actually need to save.
Deadlines Described in Months Feel Far Away. Here Is Why Days Work Better.
Behavioral research shows people act faster on deadlines expressed in days than months, even when the time remaining is identical. Here is why the unit matters.
A Valid Email Address Can Still Bounce. Here Are the Three Layers of Validation and What Each One Catches.
Email validation has three layers: syntax, domain DNS, and mailbox existence. Tools can verify the first two. The third is blocked by major providers to prevent address scraping.
JSON Was Designed for Machines. YAML Was Designed for People. Here Is Why That Matters for Configuration Files.
JSON requires quotes on every key and precise trailing commas. YAML removes that friction. Here is why teams convert JSON configs to YAML for team maintenance.
Your Hard Drive Is Smaller Than Advertised. Here Is Why That Is Legal, Expected, and Entirely the Result of a 1950s Naming Convention.
A kilobyte is 1,000 bytes to hard drive makers and 1,024 bytes to your OS. This naming dispute from the 1950s still shrinks every drive you buy. Here is the full story.
Hans Peter Luhn Filed a Patent to Catch Punch Card Errors in 1954. It Now Validates Every Credit Card on Earth.
Luhn's 1954 IBM patent was designed to catch transcription errors on punch cards. His mod-10 formula now validates every Visa, Mastercard, and Amex number worldwide.
The Designer Approved the Red. The Printer Matched the File. The Color Was Still Wrong. Here Is Why.
HEX colors exist in sRGB, which can't reproduce all Pantone colors. Screen colors are emissive. Print colors are reflective. Here is how color spaces explain the gap.
Twitter Doubled the Character Limit to 280. Only 1 Percent of Tweets Used the Extra Space.
Twitter's 140-character limit came from SMS text message constraints, not writing research. When it doubled to 280 in 2017, only 1% of tweets used the extra space.
Why Every Computer in the World Counts from January 1, 1970 -- And What Breaks in 2038
Unix time started at January 1, 1970 by pragmatic accident. The same 32-bit integer choice that made it compact is what causes an overflow at 03:14:07 on January 19, 2038.
UTM Stands for Urchin. The Company Was Named After Sea Urchins. Google Bought It in 2005 and Kept the Name.
Urchin Software built UTM tracking in 2002. Google acquired it for $30M in 2005 and kept the parameter names. Here is what each of the five parameters actually tracks.
WebP Transparency vs PNG Transparency: They Are Not the Same Thing
WebP and PNG both support transparency, but they behave differently outside browsers. Here's when to stick with PNG and when WebP actually wins.
John Gruber Left the Edge Cases Undefined in 2004. The Spec Wars That Followed Lasted a Decade.
John Gruber published Markdown in 2004 with intentional ambiguities. The incompatible parsers that followed took a decade and a 100-page spec to resolve.
Rotating a PDF Page Does Not Move a Single Pixel. Here Is What Actually Changes in the File.
When you rotate a PDF page, no pixels move. The /Rotate key in the page dictionary changes instead. Here is why that matters for printing and workflows.
The Blog Migration Looked Successful. Six Weeks Later Traffic Was Down 35 Percent. The Redirects Were Wrong.
A 302 redirect transfers no authority. A 3-hop 301 chain loses 27% of link equity. Here is how to audit redirects before a site migration costs you months of rankings.
She Published the Same Article Twice. The Second Title Drove Four Times the Traffic.
Upworthy's 8,977-headline archive reveals what makes titles work. The answer is an information gap, and it has a precise optimal point research has now mapped.
When the Document Is a Thousand Pages but the Evidence Is on Pages 74 Through 78
Why extracting specific pages from a PDF matters in litigation, academic research, and compliance audits, and what makes the process technically non-trivial.
Six Major Platforms. Six Different Aspect Ratios. Here Is How to Crop One Video for All of Them.
YouTube wants 16:9. Instagram wants 9:16. TikTok wants 9:16. LinkedIn wants 1:1. Here is what cropping actually does to your video and how to handle multi-platform distribution.
30 Business Days Is 40 Percent Longer Than 30 Calendar Days. Most Contracts Do Not Specify.
When a contract says '30 days' without specifying which kind, the default is calendar days. Here is how the two diverge and why it matters for deadlines.
XML Is Verbose by Design. JSON Is Concise by Design. Here Is What You Lose When You Convert.
XML and JSON represent the same data differently. A typical XML document is 2-4x larger than the equivalent JSON. Here is what features cannot survive the conversion.
camelCase, snake_case, and kebab-case: Why Programmers Cannot Agree on a Simple Naming Rule
Why programmers use camelCase, snake_case, and kebab-case — and why they can't agree. The history of naming conventions from Bell Labs to modern JavaScript.
Whitespace in HTML Is Semantic, Not Decorative. Formatting It Correctly Requires Knowing the Difference.
Whitespace between inline HTML elements changes what appears on screen. A formatter that normalizes it aggressively can break your layout. Here is how to format HTML safely.
Four Formulas Give Four Different Answers for Ideal Weight. None of Them Were Designed for Fitness.
Hamwi, Devine, Robinson, and Miller were all created for drug dosing or insurance actuarial tables, not fitness targets. Here is what each formula actually measures.
Your IP Address Shows Where Your Connection Is Registered, Not Where You Are. Here Is the Difference.
IP geolocation maps IP address registrations, not GPS positions. Country detection exceeds 99%. City-level accuracy varies by carrier and region. Here is why.