Featured article · 30 October 2026 · 6 min read
How to convert L/100 km to mpg correctly
L/100 km and mpg run in opposite directions. Exact formulas for US and UK gallons, a quick reference table and how to turn consumption into trip cost.
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Notes on browser tools, privacy, performance and the occasional deep dive into a unit conversion.
Tool guides · 4 min read
JSON validator, formatter and minifier guide
Paste JSON to validate it, format it with two-space indentation, or minify it. Error messages include the line and column where parsing stopped.
Tool guides · 4 min read
Base64 encoding explained (and when not to use it)
Encode text to Base64 or decode Base64 back to text. The encoder writes UTF-8 bytes first, so accented characters and emoji survive the round trip.
Tool guides · 4 min read
URL encoding: when to use encodeURIComponent
Percent-encode a URL component or a whole URL, and decode percent-encoded text back. Encoding follows encodeURIComponent / encodeURI.
Tool guides · 4 min read
MD5 vs SHA-256: which hash should you use?
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 for any text. Input is encoded as UTF-8 before hashing, so results match command-line tools and online verifiers.
Tool guides · 4 min read
How to minify CSS safely
Remove comments and unnecessary whitespace from CSS and see how many bytes you saved. Runs entirely in the tab.
Tool guides · 4 min read
UUID v4 vs v7: choosing the right identifier
Generate up to 100 RFC 4122 version 4 UUIDs at once with the browser crypto generator, then copy the list.
Tool guides · 4 min read
How to read a JWT safely
Paste a JSON Web Token to read its header and payload, with issued-at and expiry decoded to dates. Nothing is verified or sent anywhere.
Tool guides · 4 min read
How to format SQL without changing the query
Format a SQL statement with the major clauses on their own lines and keywords in upper case, or minify it back to one line.
Tool guides · 4 min read
Characters vs bytes: counting text correctly
Count characters, words, lines and UTF-8 bytes as you type. Useful for meta descriptions, form limits and database columns.
Tool guides · 4 min read
camelCase, snake_case and kebab-case explained
Convert text between lower case, UPPER CASE, Title Case, Sentence case, camelCase, snake_case, kebab-case and PascalCase.
Tool guides · 4 min read
Unix timestamps: seconds, milliseconds, time zones
Convert Unix timestamps in seconds or milliseconds to local time, UTC, ISO 8601 and a relative phrase, or turn a date back into a timestamp.
Tool guides · 4 min read
Unit conversion: exact factors and temperature
Convert length, mass, volume, temperature, speed, area, time, data, pressure, energy, power and fuel economy with exact factors.
Tool guides · 4 min read
Time zone conversion without DST mistakes
Convert a date and time from one time zone to another using the browser IANA time zone database, including a meeting-friendly comparison list.
Tool guides · 4 min read
How to calculate age precisely
Enter a birth date to get the exact age in years, months and days, plus total days and the next birthday countdown.
Tool guides · 4 min read
RGB to HEX to HSL: a practical guide
Convert between RGB, HEX and HSL, with a live colour preview and the nearest common colour name.
Tool guides · 4 min read
Picking colours for the web: HEX, RGB, CSS
Pick a colour and read it as HEX, RGB, HSL and CSS variables ready to paste into a design system.
Tool guides · 4 min read
Percentage increases and decreases explained
Three percentage questions in one tool: X% of Y, X is what percent of Y, and the percentage increase or decrease between two numbers.
Tool guides · 4 min read
BMI explained: what it measures and misses
Calculate body mass index from height and weight in metric or imperial units, with the standard WHO category bands.
Tool guides · 4 min read
How to generate strong passwords
Generate strong passwords locally with the browser crypto generator. Choose length and character sets, and see the entropy estimate.
Tool guides · 4 min read
Lorem ipsum: when placeholder text helps
Generate placeholder paragraphs, sentences or words for mockups and layout tests.
Tool guides · 4 min read
Word count and reading time explained
Count words, characters, sentences and paragraphs, with an estimated reading time and the most frequent words.
Tool guides · 4 min read
Trip fuel cost: estimate what a drive costs
Estimate what a trip costs in fuel: enter distance, consumption and the price at the pump, and get the total spend plus the litres or gallons burned.