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CSV Data Grouper Field Guide: When the Group By Finally Talks Back
Group by a column, pick an aggregator, and the CSV summary writes itself. When a…
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Light-Year & Astronomical Unit Converter Field Guide: When the Parsec Was Built to Match the Arcsecond
A light-year is not a year of light. It is a distance measured in meters,…
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ReDoS Scanner Field Guide: When One Regex Holds the Whole Request Thread
One nested-quantifier group inside a single JavaScript regex can pin a Node event loop at…
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UPC/EAN Barcode Validator Field Guide: When the Mod-10 Catches the Bad One
A field guide to the mod-10 weighted checksum baked into the last digit of every GTIN-8, GTIN-12, GTIN-13, and GTIN-14 barcode on every shelf.
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CUSIP Validator Field Guide: The Mod-10 Check That Quietly Catches Bad Securities IDs
Every North American stock, bond, and ETF ticker rides on a nine-character code, and the…
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RFC 2822 Converter Field Guide: When Email Headers Beat ISO 8601
A field guide to RFC 2822 dates: how email, HTTP, and legacy archives parse them, what the four converter operations actually do, and how to audit output before shipping.
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Capitalize Sentences: A Surgical One-Letter-Per-Sentence Fix
Sentence starts need to be capital, but the rest of the text already has the caps it wants. A surgical one-letter-per-sentence fix beats a blanket re-case every time.
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WebSocket Tester Field Guide: Four Opcodes, Seven Events, Three Bugs
A WebSocket connection is a long-lived TCP socket that both sides can write to at…
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HTTP Request Tester: a mini Postman that lives in your browser
What an in-browser HTTP client actually solves The shortest path to a real HTTP response…
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Superscript & Subscript Converter Field Guide: Unicode That Survives the Copy-Paste
Real Unicode glyphs beat HTML and tags when you want chemistry, math exponents, and footnote markers to survive the copy-paste into chat, code, and filenames.