Blog
Practical SEO and web-dev guides — no fluff, with the free tools to act on them.
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Structured Data & JSON-LD: A Practical Guide to Rich Results
A developer-focused guide to structured data and JSON-LD — what schema.org markup actually does for search, why JSON-LD beats microdata, which schema types earn rich results, where to put the script, and how to validate it before it ships.
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How TOTP 2FA Codes Actually Work: Shared Secrets, Time Steps & QR Codes
A developer-friendly breakdown of TOTP — the six-digit codes from authenticator apps. How the shared secret gets into your phone via a QR code, why the code changes every 30 seconds without any network connection, what HMAC and the time step do, and how the server verifies it.
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CIDR & Subnetting Explained: Reading /24, Masks, and Host Counts
A no-memorization guide to CIDR notation and subnetting — what the slash number really means, how to count hosts in a /24 or /20, why the network and broadcast addresses are reserved, how subnet masks work in binary, and the quick mental math for everyday networking.
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How bcrypt Actually Works: Salts, Cost Factors & Why You Never MD5 a Password
A developer-friendly explanation of bcrypt — why password hashing is different from regular hashing, what the salt and cost factor in a $2b$ string mean, how deliberate slowness defeats brute-force attacks, and why MD5 and SHA-256 are the wrong tools for passwords.
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UUID vs ULID: v4, v7, and Which ID You Should Actually Use
A practical comparison of UUID and ULID for generating unique IDs — how UUIDv4, UUIDv7, and ULID differ, why random IDs wreck database index performance, what "sortable" really buys you, and a clear decision guide for picking the right identifier in 2026.
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How to Test File Upload Limits: Boundaries, 413s, and Exact-Size Files
A practical developer guide to testing file upload limits correctly — nginx client_max_body_size, cloud function payload caps, S3 multipart thresholds, the MB vs MiB unit trap, and how to generate exact-size test files in any format.
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Sample File Sizes for Testing: 1 MB, 10 MB, 100 MB and Why They Matter
A practical guide to which file sizes you should actually test, the real-world thresholds they map to (form uploads, API gateways, CDN edge limits), the decimal MB vs binary MiB gotcha that causes off-by-5% limit bugs, and why round numbers are the worst test inputs you can pick.
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What Makes a File Valid? Magic Bytes & File Signatures Explained
How programs really know what a file is — not from its extension, but from the raw bytes at the start. A developer-friendly look at magic numbers, MIME sniffing, structural validity, and why renaming a .txt file to .pdf does not make a PDF.
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How ZIP Files Actually Work: Local Headers, Central Directory & the End Record
A developer-friendly deep-dive into the ZIP binary format — the three structural sections every archive contains, why a ZIP reader seeks from the end rather than the beginning, how STORE and DEFLATE differ, and what really happens when a tool reports your archive is corrupt.
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PNG vs JPG vs WebP vs AVIF: Which Format to Use and When
A practical breakdown of the four main web image formats — PNG, JPG, WebP, and AVIF — covering lossless vs lossy, alpha transparency, compression efficiency, browser support in 2026, animation, encode/decode cost, and a clear decision guide for developers.
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Cron Syntax Cheat Sheet: Fields, Examples & Special Strings
A clear cron cheat sheet: what each of the five fields means, the special characters, @daily-style shortcuts, ready-to-use schedule examples, and the day-of-week gotcha that catches everyone.
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How Font Files Actually Work: TTF, OTF, WOFF & WOFF2 Explained
A developer-friendly look at what is really inside a font file — sfnt tables, TrueType vs CFF outlines, and why WOFF/WOFF2 are just compressed containers. Plus when converting between formats is lossless and when it is not.
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Git Cheat Sheet: The Commands You Actually Use (with the Gotchas)
A practical Git cheat sheet grouped by what you are trying to do — commit, branch, undo, stash, sync, and recover — with the gotchas that bite people. Copy-paste ready.
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How JWTs Actually Work: Header, Payload, Signature & Common Mistakes
A developer-friendly explainer of JSON Web Tokens — what the three parts really are, what signing does and does NOT do, how validation works, and the security mistakes that cause real breaches.
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Regex Cheat Sheet: Syntax, Patterns & Copy-Paste Examples
A practical regular expression cheat sheet — anchors, character classes, quantifiers, groups, and lookarounds — plus ready-to-use patterns for email, URLs, dates and more, and the gotchas to avoid.
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The Best Free SEO Audit Tools for Developers (No Signup)
An honest roundup of free SEO audit tools for developers — including competitors — judged on depth, signup friction, and the technical checks that actually matter.
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Core Web Vitals Explained: LCP, INP, and CLS for Developers
What LCP, INP, and CLS actually measure, the thresholds that matter, and the real causes behind each failure — written for developers, with concrete fixes.
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The Complete On-Page SEO Checklist (45 Checks, Free Tools Included)
A practical, developer-focused on-page SEO checklist for 2026 — meta tags, headings, content, links, images, structured data, Core Web Vitals, security headers, and crawlability, each with a free tool to check it.
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A Free SEOptimer Alternative — No Email, No Paywall
Looking for a free SEOptimer alternative that does not gate the report behind an email signup? Here is an honest comparison and a no-signup, browser-based option for developers.
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