Guides
Short, practical explainers on the problems these tools solve — file formats, compression, metadata, QR codes and the math behind the calculators.
These are written as standalone references. You’ll find honest numbers, common gotchas, and the actual trade-offs (lossy vs lossless, when extra payments help, what EXIF really contains) so the tools become more useful.
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How extra payments actually save money on mortgages and loans
Why the first years are almost all interest, how every extra dollar compounds the savings, and exactly what the amortization schedule is showing you. Numbers you can use with any calculator.
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Digital signatures on PDFs: visible stamps vs real cryptographic signatures
What “Sign PDF” actually does, the difference between a picture of a signature and a cryptographic signature, why self-signed certs look untrusted, and what survives when you email the file.
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How image compression actually works — and when it hurts quality
JPEG DCT blocks, PNG filters, WebP and AVIF, lossy vs lossless, generational loss, and exactly what the quality slider is trading. Practical rules for photos, screenshots, logos and print.
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Inside a PDF: why files get huge and what compression actually changes
PDF objects, streams, xref tables, image vs text bloat, incremental saves, and the real difference between “compress images” and “restructure the whole document”. What you can safely shrink and what you cannot.
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Professional invoices: what actually gets paid (and common mistakes)
Layout, required details, tax/VAT handling, payment terms, and the small things that make the difference between “I’ll get to it” and “paid today”. All in the browser, no account needed.
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Compound interest, explained with real numbers
Why starting ten years earlier beats contributing twice as much, what monthly compounding actually does, and how to sanity-check any projection — including ours.
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JPG, PNG or WebP? How to pick an image format
A practical decision guide to the three formats you actually meet: what each one is good at, where each one fails, and the conversions that make sense (and the ones that don’t).
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Why PDFs get huge — and how to actually shrink them
A 40 MB PDF is almost never 40 MB of text. Where the size really comes from, which compression tricks work, and what you give up with each one.
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Static vs dynamic QR codes — what “free” QR generators don’t tell you
Why QR codes from free generator sites stop working, how scan tracking works, and when a plain static code is simply better. Plus how error correction keeps damaged codes scannable.
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Scanning documents with your phone: from photos to a clean PDF
You don’t need a scanner — you need decent light, a steady phone and the right way to turn the photos into a small, ordered, shareable PDF. Here’s the whole workflow.
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Your photos know where you live: EXIF data, explained
Every phone photo carries hidden metadata — GPS coordinates, device details, timestamps. What’s actually in there, when it matters, and how to remove it before sharing.
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How to send photos that are “too big” — without wrecking them
Email bounced your attachment, a form rejected your upload? Here’s why photos are so large, what actually makes them smaller, and how to shrink them without visible quality loss.
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What is a HEIC file? The iPhone photo format, explained
Why your iPhone photos won’t open on Windows, what HEIC actually is, whether you should switch your camera to JPEG, and the fastest ways to convert when something refuses the format.
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