Front-end developer and tech writer · View profile
· 10 min read
A rental file, a loan application, a tender: the requester wants one document, in the order they listed. The merge itself takes seconds. What goes wrong is the ordering, the page sizes and the file that silently loses its signature — all of which are avoidable if you know where they bite.
· 9 min read
Marketplaces, job boards and support forms often accept JPEG and PNG and nothing else. Converting is easy; choosing the resolution is the part that decides whether the recipient can read your document, and it is the part every tool asks you about and nobody explains.
· 10 min read
The first pass takes 30% off and the second takes nothing. That is not a broken tool — it is the difference between removing redundancy and removing information, and knowing which one you are doing tells you when to stop and what a second attempt actually costs.
· 11 min read
The form rejects your file and offers no advice. What works depends entirely on where the megabytes actually are, and for a scanned document the answer is not compression at all — it is resolution. Here is how to tell which case you have in ten seconds.
· 12 min read
Every online file tool promises your document is safe. Almost none tell you whether it leaves your machine at all. There is a five-second test that settles it without reading a single privacy policy, and it works on any tool — including this one.
· 10 min read
The DPI figure inside an image file is a label. It changes no pixels. Printed size is pixels divided by PPI — and DPI, properly used, means something else entirely: the printer's dots.
· 13 min read
A photo file carries coordinates, an exact timestamp, the device and lens, and on some cameras a serial number. Here is what is actually in the block, what stripping does and does not fix, and how to verify it worked.
· 13 min read
Two properties decide the format — photographic or flat-toned, and whether it needs alpha or animation. Everything else is downstream. With measured byte counts for the same two images in all four formats.
· 9 min read
Minute, hour, day of month, month, day of week. The traps are that a step is a stride through a range and not an interval, and that the two day fields are combined with OR — so 0 0 1 * 1 fires on the 1st and on every Monday.
· 9 min read
Four directives, two wildcards, one file at the host root. It is a crawl instruction and nothing more — it does not remove a page from search results, it does not restrict access, and it publishes every path you list in it.
· 7 min read
Nothing is styled. Each letter is swapped for a different Unicode character that happens to look bold or cursive — which is why a screen reader reads the result as gibberish and some devices show empty boxes.
· 8 min read
301 against 308, 302 against 307, 401 against 403, 404 against 410 — plus what Retry-After on a 429 or a 503 actually promises. The pairs where picking the wrong code changes behaviour, not just wording.
· 7 min read
Read is 4, write is 2, execute is 1, and each of the three digits describes a different party. The part most explanations get wrong is what the execute bit does on a directory — it grants traversal, not the right to run anything.
· 4 min read
Every game uses a different sensitivity scale. Convert with the yaw ratio, verify with centimetres per 360 degrees, and keep the muscle memory you spent months building.
· 4 min read
Estimate upload time with one formula: file size in bits divided by your upload speed. Learn why upload is usually slower than download and how overhead affects the result.
· 4 min read
A conversion rate is the share of visitors who take a desired action. Here is the simple formula, typical benchmarks, and how to read the number without fooling yourself.
· 4 min read
Big O describes how an algorithm's work grows as input grows. Here is what O(1), O(n), O(n squared), and O(log n) mean and why the difference matters.
· 4 min read
Unicode assigns every character a code point; UTF-8 encodes those code points in one to four bytes. Here is how it works and why it beat the alternatives.
· 4 min read
Click-through rate measures how many people click after seeing your ad or link. Learn the clicks ÷ impressions × 100 formula and typical benchmarks by channel.
· 5 min read
A step-by-step guide to billable hours: separate billable from non-billable time, work out your utilization rate, and project the annual revenue your hours can produce.
· 4 min read
Burn rate is how fast a startup spends cash each month. Learn to compute net burn, turn it into runway with cash ÷ burn, and read the number before it reads you.
· 4 min read
What password entropy really measures, why length beats complexity, and how bits of entropy translate into a realistic crack time.
· 2 min read
A Unix timestamp counts the seconds since January 1, 1970 UTC. Learn why computers use it, how to convert it, and the 2038 problem.
· 4 min read
An employee costs far more than their gross salary. Learn how payroll taxes, benefits and overhead push the total to roughly 1.25–1.4× the salary, with a worked example.