Front-end developer and tech writer · View profile
· 7 min read
The last resort when nothing can be compressed further. It works, and it has three sharp edges: the parts are useless on their own, the order is absolute, and the megabyte you set is not the megabyte the limit means.
· 19 min read
Plain text has no layout, so any converter has to invent one for you. Here is exactly which decisions this one makes — page, margins, font, line breaks — what it does with a tab and a long line, and what you have to add yourself before a note is worth keeping.
· 19 min read
Three completely different faults hide behind the same sentence. One is the encoding, one is the separator, one is Excel guessing at types while it opens the file — and the fix for each is different. Here is how to tell them apart in five seconds.
· 18 min read
That tick at the edit point is not a flaw in the software. It is a step in the waveform, and a step is broadband energy — which is the definition of a click. Here is the arithmetic, measured, and the two places you can put a cut so it never happens.
· 15 min read
Folding diacritics is a normalisation step, and normalisation only works when the same function runs on the index and on the query. NFC against NFD with the code points shown, and the letters — ø, ł, ß, œ, ı — that survive the strip untouched.
· 14 min read
Strip tags before decoding entities, trim before deduplicating, collapse whitespace last. Three orderings run in Node, a nine-step pipeline in the right sequence, and the invisible characters — U+00A0, U+200B, U+FEFF — that survive every naive cleanup.
· 15 min read
One of these formats stores the samples, one stores the same samples packed smaller, and one stores a guess about what you would have heard. Which conversions between them are free, which are merely expensive, and which are one-way doors — with the arithmetic for each.
· 15 min read
The soundtrack inside your video has already been through a lossy encoder once. Whether extracting it costs you a second pass depends entirely on which of the three buttons you press — and "extract to MP3", the one everybody reaches for, is the one that costs.
· 16 min read
Percent-encoding is decided per URL component, which is the whole source of the confusion. A slash is legal in a path and must be escaped in a query value; a space is %20 in a path and may be + in a form body. Here are the exact RFC 3986 sets, the three JavaScript functions that disagree, and the traps.
· 14 min read
A GIF has no real video compression: every frame is a whole picture, capped at 256 colours. That gives you an arithmetic you can do in your head — width times height times frames — and three levers to pull when the upload box says the file is too big.
· 16 min read
Entropy measures the process that produced a password, not the characters in it. H = L x log2(R) is only true when every character was chosen at random — which is exactly why a meter scoring a human-invented password on its character classes is measuring the wrong thing.
· 16 min read
A JWT is signed, not encrypted. Anyone holding the token can decode the payload and read every claim in it. Here is a real token, decoded without any key, plus the three attacks the signature is supposed to stop and the one problem it cannot solve.
· 11 min read
Going from 1080p to 720p does not halve the picture: it removes 56 % of the pixels, and it removes rather less than that of the file. Here is the ladder with real pixel counts, honest bitrates and what three minutes weighs at each rung — plus the reason a low-bitrate source barely shrinks at all.
· 12 min read
The conventions are not taste. A hyphen is the minus operator, so kebab-case cannot be an identifier in most languages - which is exactly why CSS and URLs use it. Plus the acronym round-trip that silently corrupts names, and the rule that fixes it.
· 14 min read
The quality slider cannot aim at a file size — that is not what it is for. But the limit and the length of your clip already fix the bitrate you are allowed to spend, and one division tells you whether the resolution you are using can possibly fit.
· 14 min read
The extension is almost never the real problem. A .mov and a .mp4 are cousins from the same family of file formats, and what actually stops the video is the codec sealed inside it — usually HEVC. Here is how to tell the two failures apart, and when changing the box is enough.
· 7 min read
You asked for 1:23 and got 1:21. Nothing is broken: a cut that does not re-encode can only land on a keyframe, and how far away the nearest one is depends entirely on what recorded the video. Here is how to know which you have and when to accept the drift.
· 11 min read
A landlord wants page 3. An accountant wants January. You need to send those pages and not the eleven others, and there is a trap: the obvious way leaves the removed pages inside the file you send.
· 8 min read
A duplex scanner that took one side at a time, a stack fed upside down, a page that came out twice. Reordering is not the same operation as extracting pages, and knowing which one you are doing tells you what happens to everything that is not a page.
· 8 min read
You rotated the scan, saved it, and the recipient still opened it sideways. Nothing is broken — rotation in a PDF is an instruction rather than a change to the page, and instructions can be ignored. Here is when that happens and how to produce a file that cannot be misread.
· 11 min read
A character is three different things at once. One emoji with a skin tone is 1 grapheme, 2 code points and 4 UTF-16 units. Every count in this guide was measured in Node, plus why an SMS drops from 160 to 70 and why VARCHAR(255) is not 255 of anything in particular.
· 15 min read
MD5 is broken and MD5 is fine, depending on which of three security properties you needed. Here is what collision resistance, second-preimage resistance and preimage resistance actually mean, which algorithm still has which, and why none of them belongs near a password.
· 9 min read
Nobody owns a scanner any more, so the phone does it. Two things decide whether the result is accepted: how you took the photograph, and what page size it becomes. The second one surprises people, because a photograph turned into a PDF is not A4 unless something makes it A4.
· 11 min read
Flesch Reading Ease and Flesch-Kincaid Grade Level count syllables and sentence length. Nothing else. Both formulas in full, one passage scored end to end, and the comma trick that buys 3.9 grade levels without changing a word.