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Articles about JSON, Base64, UUIDs, cron and more. Practical guides for developers.
WebP, JPG or PNG: which image format to use and when
The real differences between JPG, PNG and WebP, when each one makes sense, and how to convert a WebP that won't open in Word, PowerPoint or a web form.
Related tool: Image Converter: PNG, JPG and WebPMerge and split PDFs without uploading your documents
Why you shouldn't upload contracts, payslips or invoices to just any PDF website, how to merge and split pages in your own browser, and what's preserved when you do.
Related tool: Merge PDFHow to reduce a photo's file size for an online form or an email
What to do when a website says "file exceeds the maximum size": how to get a photo under 1 MB without it looking worse, and why width matters more than quality.
Related tool: Compress Images OnlineHow to turn photos of documents into a PDF (IDs, receipts and paperwork)
Turn phone photos of an ID card, a receipt or a contract into a single readable, lightweight PDF ready for an online form or an email, without installing anything.
Related tool: Convert Images to PDF (JPG to PDF)How to remove VAT from a price (and why taking off 20% gives the wrong answer)
The correct formula to get the net amount from a VAT-inclusive price, with examples at 20% and 5%, the 1/6 shortcut and the mistakes that most often break invoices.
Related tool: VAT CalculatorMD5 vs SHA-1 vs SHA-256: the differences and which one to use
What a hash is, why MD5 and SHA-1 are no longer secure, what each one is still good for, and why none of the three should ever be used to store passwords.
Related tool: Text HashCron cheat sheet: syntax and 20 ready-to-copy examples
How to read a cron expression field by field, the examples people use most (every 5 minutes, weekdays, first Monday of the month…) and the mistakes that make a job run when you don't expect it.
Related tool: Cron Expression ParserHow an exact age in years, months and days is actually calculated
Why subtracting birth year from the current year isn't enough for an exact age, and how the edge cases are handled: February 29 and time zone shifts.
Related tool: Exact Age CalculatorHow to calculate VAT correctly (and the mistakes everyone repeats)
The difference between price with and without VAT, common tax rates, and the rounding mistakes that break invoices.
Related tool: VAT CalculatorEveryday regex: the patterns you'll reuse forever
A practical cheat sheet of regular expressions for emails, URLs, phone numbers and passwords, plus the most common mistakes when writing them.
Related tool: Regular Expression TesterWhat a JWT is and how to decode one without libraries
The anatomy of a JWT (header, payload, signature), how to read one without installing anything, and why decoding isn't the same as verifying.
Related tool: JWT DecoderSubnetting without the headache: how to calculate an IPv4 subnet
CIDR, network mask, broadcast and usable hosts explained with examples, plus the /31 and /32 special cases almost nobody remembers.
Related tool: Subnet CalculatorTruly strong passwords: why length beats symbols
What password entropy is, how many bits you need to be safe, and why 16 simple characters beat 8 with symbols.
Related tool: Secure Password GeneratorWiFi and contact QR codes: how they work under the hood
The standard text format behind WiFi and vCard QR codes, what L/M/Q/H error correction means, and how to generate them correctly.
Related tool: WiFi QR Code GeneratorUnix timestamps: what they are and why half of all date bugs start here
What a Unix timestamp is, the difference between seconds and milliseconds, the Year 2038 problem, and how to convert it without mistakes.
Related tool: Unix Timestamp ConverterColor contrast and WCAG accessibility: the guide to check before you ship
What the WCAG contrast ratio is, the AA and AAA minimums you need to hit, and how to fix a color combination that fails.
Related tool: WCAG Contrast CheckerBase64: what it is, when to use it, and when it's a mistake
How Base64 encoding works, what it's actually good for in APIs and images, and why it isn't the same thing as encryption.
Related tool: Base64 Encode/DecodeHow to convert units without errors (and without losing your mind)
A practical guide to converting length, weight, area, volume and data units without manual mistakes, using our online converters.
Related tool: Unit ConverterWord counters for SEO: which metrics actually matter
How to use a word counter as part of your SEO routine: density, readability and the metrics worth watching in every article.
Related tool: Word and Character Counter