Step-by-step walkthroughs for everyday tasks, each with the tool that does the job.
Check whether a changed DNS record is visible across major public resolvers, why some still show the old value, and how TTL decides how long you wait.
Pick the right subnet mask for the number of devices you need, then split one network into right-sized subnets with a VLSM plan.
Tell search engines which language version of a page belongs to which audience: list every version, make the tags reciprocal, add x-default and keep canonicals consistent.
Tag links with utm_source, utm_medium and utm_campaign so analytics shows which email, post or ad sent each visit, with a naming convention that stays clean.
Build an XML sitemap from your list of URLs, validate it, publish it at /sitemap.xml, reference it in robots.txt and submit it to the search engines, plus an optional llms.txt for AI assistants.
Turn a website into an installable app: serve it over HTTPS, prepare 192 and 512 pixel icons, write a web app manifest, link it from the page and check the installability requirements.
Shrink stylesheets and scripts by removing comments, whitespace and redundant code: run each file through a minifier, compare sizes, test the result and serve it compressed.
Protect your pages from a tampered CDN file: hash the exact file, add the integrity and crossorigin attributes, test that the browser blocks a modified copy and plan for updates.
Inspect a link you do not trust without opening it: defang it, read its real host, spot lookalike characters, expand shorteners and follow the redirects.
Check a website's HTTPS certificate: whether it validates, when it expires, which names it covers, who issued it and whether the chain is complete.
Read an email's raw headers to see whether it really came from the domain in the From line: SPF, DKIM, DMARC alignment and the Received chain.
Choose between a random password and a passphrase, pick a length from the entropy numbers, store it in a password manager and add a second factor.
Publish the three DNS records that stop others sending mail as your domain: list your senders, write SPF, publish a DKIM key, start DMARC at p=none and tighten it.
Confirm a download is complete and untampered by comparing its SHA-256 checksum with the published value, in the browser or on the command line.
Turn an API response into a spreadsheet-ready CSV and a CSV back into JSON, with notes on how columns, nested values and data types are handled.
Prepare a PDF for sharing: fix sideways pages, stamp a watermark and page numbers, remove author and software metadata, and check the result still reads correctly.
Combine several PDFs into one, pull out the pages you need, reorder or rotate them, and add page numbers, all in your browser with nothing uploaded.
Check a gamepad for stuck buttons, stick drift and vibration, then measure your screen's real refresh rate and frame-time jitter and look for dead pixels.
Check your camera, microphone, speakers, display and keyboard before a call or after buying new gear, using browser tests that upload nothing.
Put loan offers side by side: monthly payment, total interest, fees, cost of borrowing and fee-inclusive APR, and how early repayment changes the winner.
Turn your income and debts into a monthly housing budget with the 28/36 rule, convert that into a price range, then plan the down payment and closing costs.
Find out whether a PDF was edited after it was created or signed: incremental saves, changed text between revisions, weak redactions and signature coverage.
Check a photo for signs of editing: metadata, the embedded preview, JPEG recompression traces, error level analysis, noise and cloned regions.
Read the GPS coordinates a phone or camera stored in a photo, check them against the capture time and daylight, and remove them from your own pictures.
Load Linux auth logs or Windows Security events, tell brute force from password spraying, spot a login that succeeded, and look up who the source IPs belong to.