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What actually happens to a file you upload, what your own device can do instead, and how to check any tool's claims for yourself.

71 articles

PDF

pdf tools
  1. PDF tools that don’t upload your filesPeople look for a Smallpdf or iLovePDF alternative after noticing the upload. The architectural difference, what each approach is better at, and how to test any tool yourself.7 min
  2. How to merge PDF files without uploading themWhat actually happens to a document you upload to a PDF site, how browser-based merging avoids it, and how to verify any tool’s claim in thirty seconds.8 min
  3. Why you can’t copy text out of a PDFTwo documents look identical on screen; one holds no text at all. How to tell which you have in five seconds, and what to do about each.8 min
  4. Why a scanned PDF is 40 MB and a typed one is 400 KBA scanner photographs every page. Where the megabytes come from, which can be recovered, and why some PDFs will not shrink at all.8 min
  5. How to compress a PDF to 100 KB, 500 KB or 1 MBA form says 2 MB and the quality slider makes you guess at it. How to land under a limit on the first try, and how to tell when a target is impossible.7 min
  6. How to fill in a PDF form that won’t let you typeMost PDF “forms” have no fields at all — they are pictures of forms. What to do with each of the three kinds, and how to sign one.7 min
  7. What your PDF knows about youYour name, your software, your machine, and sometimes the text you deleted. Where a PDF stores each of them, and what actually removes it.8 min
  8. What cropping a PDF actually does — and what it does notA crop sets a viewing window. Everything outside it is still in the file, and one click brings it back. What to do when it genuinely has to go.6 min
  9. How to delete pages from a PDFRemoving a page from the view and removing it from the file are different operations, and most tools do the first. How to tell which one you got.7 min

Image

image tools
  1. JPEG, PNG, WebP or AVIF — how to chooseOne question decides it, and it is not the one people ask. What each format throws away, and the two mistakes that cost the most.8 min
  2. What your photos reveal about youThe GPS coordinates, serial numbers and timestamps hidden in every photograph you take — where they come from, who can read them, and how to remove them.9 min
  3. Pixels, inches and DPI — what image size actually meansAn image has one real dimension and DPI is not it. Why “save it at 300 dpi” adds no detail, and the one calculation that does matter.7 min
  4. Why your photo is sideways on one device and not anotherThe camera did not rotate the picture. It wrote a note asking someone else to, and not everyone reads it.6 min
  5. How to make a favicon that works everywhereFour files, not forty. Which sizes still matter, why a shrunk logo never works, and the design constraint nobody mentions.6 min
  6. How to compress an image without wrecking itThe quality slider is not a percentage of anything. What JPEG throws away, why 100 wastes half the file, and the step that beats it.8 min
  7. How to resize an image without making it blurryMaking an image smaller is safe and making it larger is not, and the reason is the same either way. What resampling does, and the sizes worth resizing to.7 min
  8. How to make a GIF smallerA GIF stores every frame whole, in 256 colours, with a compressor from 1987. Why quality settings barely move it, and what does.6 min

Text

text tools
  1. How to find and remove hidden characters in textThey look like nothing and break search, sorting and code. Where zero-width and non-breaking characters come from, and how to strip them.8 min
  2. Why every tool gives you a different word countWord, Google Docs, Twitter and your CMS all count differently — and the rules are stranger than you would expect. What each one measures, and which number to trust.8 min
  3. How to copy text from a PDF without the line breaksEvery line arrives as its own paragraph, and Word will not reflow it. Why a PDF has no paragraphs, and how to put them back correctly.7 min
  4. Title case rules, and why four style guides disagreeAP, Chicago, MLA and APA each capitalise differently. What they agree on, where they split, and the two words that catch everybody.7 min
  5. Em dash, en dash, hyphen — which one and whenThree horizontal lines, three different jobs. How to type each, and why one of them became an accusation.6 min
  6. How to compare two texts and see exactly what changedReading both versions yourself does not work — the eye skips. What a diff computes, and why it reports changes nobody made.7 min

Convert

convert tools
  1. Why your 1 TB drive shows as 931 GBNobody stole your storage. Two systems of measurement share the same abbreviations, and one popular operating system labels its numbers wrong.7 min
  2. Unix time, and how to read a timestampA ten-digit number that is a date. Where the count starts, how to tell seconds from milliseconds, and what happens in 2038.7 min
  3. How to convert time zones without getting it wrongThe abbreviations are ambiguous. Offsets are not all whole hours, clocks change on different dates, and here is what to use instead.7 min
  4. Percentage increase, decrease and changeFour questions share one word, and the formulas are not interchangeable. Which to use, and why a 50% rise then a 50% fall loses money.7 min
  5. How to count the days between two datesWhether both ends count. What a working day is, why “three months later” has no single answer, and the leap year Excel invented.6 min
  6. Roman numerals: chart, rules, and why there is no zeroCharts for 1–20, the tens and the hundreds. Plus the four rules, the years you will meet, and where the system stops.6 min
  7. How big is a dunam?A thousand square metres today, nine hundred and nineteen in an old deed, two and a half thousand in Iraq. Which one a document means, and how to tell.6 min
  8. Hijri and Gregorian dates, and the gap between two of themA day count is the same in every calendar; a count of months and years is not. Which of the two you are being asked for decides everything else.7 min

Security

security tools
  1. How passwords are actually crackedNot by typing guesses into a login form. What a real offline attack looks like, why length beats complexity, and why the advice you were given made things worse.10 min
  2. Base64 is not encryptionIt looks scrambled and hides nothing. How encoding differs from encryption and hashing, and where the confusion costs money.6 min
  3. What a JWT is, and what it is notThree parts, two of which anyone can read. What the signature proves, what the claims mean, and why you cannot log anyone out.7 min
  4. UUID versions — v4, v7, and which to useIdentifiers that never collide. And the version that fixed what purely random ones do to a database index.6 min
  5. What is actually inside a QR codeJust text, and usually a URL. How a wifi code works, why a third of it can be missing, and the one that should worry you.6 min
  6. What happens to a file when you upload itThe route a document takes through an online tool, and the four places a copy of it exists. None of it careless, none of it guaranteed.9 min

Data

data tools
  1. Why your CSV opens as gibberish in ExcelArabic turns into أحمد, every row lands in one column, and leading zeros vanish. Three separate faults with the same cause — and the one setting that fixes each.9 min
  2. How to remove blank rows from a CSV without losing a real oneFour kinds of line look empty in a spreadsheet and only three of them are. Which is which, and why deleting by eye costs you a row.5 min
  3. Why the leading zeros vanish from your CSVPostcodes, part numbers and dialling codes lose their zeros between saving and opening. The file is intact — something decided they were quantities.6 min
  4. Why your CSV starts with Three bytes at the front of the file that one program writes on purpose and another draws as rubbish. What they are for, and when to remove them.6 min
  5. Why your CSV has quotes around every fieldSome of those quotes are holding the row together and some are only habit. How to tell which, and what breaks if you strip them.6 min
  6. CSV has no standard, and that is why your file breaksRFC 4180 describes the format; it does not govern it. The four things nobody agrees on, and how to survive each.7 min
  7. JSON, YAML or TOML — which to use for whatOne is for machines talking to machines, one is for humans editing configuration. Plus the YAML feature that keeps surprising people.7 min
  8. What UTF-8 actually is, and what a BOM is forWhy one encoding won. How it stays byte-identical to ASCII, and the three-byte marker that fixes Excel and breaks parsers.7 min
  9. How to turn nested JSON into a spreadsheetA tree does not fit in a rectangle. The three ways to flatten one, what each loses, and how to choose before you start.6 min
  10. Markdown to HTML — what converts, and what does notMarkdown has no single specification. Which parts every converter agrees on, which are extensions, and why tables sometimes vanish.6 min

Web

web tools
  1. The grey text problem — why light grey type failsLight grey type became the house style of the web, and it fails a measurable accessibility threshold. Where the number comes from, and the greys that actually pass.8 min
  2. Hex, RGB, HSL and OKLCH — how colour is writtenFour notations for the same colours, and one of them finally matches how your eye works. Why HSL lightness lies, and what changes.7 min
  3. Why your gradient has stripes in itSmooth in the design tool, banded on screen. Where the steps come from, why the grey middle is a separate fault, and four fixes.6 min
  4. HTML entities — which five matter, and whenThere are over two thousand and you need five. Which characters actually break markup, and why escaping everything is the wrong instinct.6 min
  5. Aspect ratios — the numbers, and how to keep themA ratio is a shape, not a size. The numbers worth knowing, the one calculation behind them, and how to stop images jumping as a page loads.6 min
  6. Meta tags that still matter, and the ones that never didSix tags do the work. Which ones, why titles are cut by pixels rather than characters, and why keywords have done nothing since 2009.7 min

SEO

seo tools
  1. Why Google cuts your title where it doesThe 60-character rule is a pixel budget restated for one alphabet. Where the real limit is, why two same-length titles cut differently, and why Arabic breaks the count entirely.7 min
  2. The robots.txt rule that blocks nothingA directive that matches nothing looks exactly like one with nothing to match. How a $ sent 35% of a week’s crawl to pages that should never have been fetched, and how to test for it.8 min
  3. Why an hreflang cluster fails silentlyGoogle discards the whole set rather than honouring half of it, and names no page when it does. The two mistakes that cause it, and how to catch both before publishing.7 min
  4. Getting structured data right before you publishThe Rich Results test needs a live URL, so the usual loop is publish, fail, fix, wait. The required fields are documented — most of that loop can happen first.7 min
  5. Sitemaps for a site in two languagesWithout alternates Google reads your two languages as competing pages and picks a winner. Why a relative href is discarded in silence, and what a correct entry looks like.6 min
  6. One capital letter splits your campaign in twoGA4 matches utm_source literally, so Facebook and facebook are two sources. The value is written onto the hit as it arrives, which is why this cannot be repaired afterwards.5 min

Subtitles

subtitles tools
  1. Why your subtitles don’t show upThe file loads, the player says nothing, and the screen stays empty. Five causes, each of which fails silently, and how to tell them apart in under a minute.9 min
  2. SRT, VTT, ASS and SBV — what each one actually holdsFour formats that look interchangeable and are not. What each can carry, what is thrown away converting between them, and which direction is safe.9 min
  3. Subtitles out of sync: offset or driftTwo faults with one symptom and two different fixes. The thirty-second test that tells you which you have, and why applying the wrong one makes it worse.8 min
  4. How fast a subtitle can be readWhere 17 characters per second and 42 characters per line come from, why they are separate limits, and why the cue that fails almost never looks like the problem.9 min
  5. Subtitles, captions and SDH are three different thingsThe words are used interchangeably and the files are not. What each is for, what removing the sound descriptions actually removes, and when that is the right thing to do.8 min
  6. How to make bilingual subtitlesTwo languages on screen at once, from two files that disagree about when every line starts. Which timing to keep, and the four ways this goes wrong.8 min

Email

email tools
  1. Why you should not upload an email to a converterThe tools on page one of the results will convert your email for you, and the guide above them tells you not to send them anything sensitive. Both are right. What to do instead.8 min
  2. What an email header actually tells youThe From line is the one part of a message anyone can write. The Received chain, SPF, DKIM and DMARC are the parts that were checked — read bottom to top, they say where it really came from.10 min
  3. EML, MSG, MBOX and PST — which is whichFour extensions for the same thing, and only one of them is a standard. What each holds, which opens anywhere, and which direction converting between them loses something.8 min
  4. How a remote image tells the sender you opened itA one-pixel image on somebody else’s server, fetched the moment the message is displayed. What it reports, why every mail client now asks before loading pictures, and what an online viewer does with it.7 min
  5. What Gmail Takeout actually gives youYou ask for your mail and get a single file of several gigabytes with an extension nothing on your computer opens. What is inside it, what is missing from it, and how to read it.8 min
  6. Why a 4MB attachment arrives as 5.4MBMail was built to carry text, so everything that is not text is rewritten as text to travel — which costs a third of the size. Base64, quoted-printable, and why the size limit bites earlier than you expect.7 min