Learn
Short, practical guides to the concepts behind our tools — PDF, email deliverability, SEO, text and developer topics, explained in plain English.
What Is an IP Address?
Learn what an IP address is, the difference between IPv4 and IPv6, public vs private IPs, and how geolocation works — in plain English.
Networking · 5 min readUnderstanding DNS Records
A clear guide to DNS and its record types — A, AAAA, MX, TXT, NS, CNAME — and how domain names get resolved to IP addresses.
Developer · 4 min readWhat Is a JWT (JSON Web Token)?
Understand JSON Web Tokens: the header, payload, and signature, how JWTs are used for authentication, and why you should never trust an unverified token.
Developer · 3 min readBase64 Encoding Explained
What Base64 is, why it exists, how it differs from encryption, and common uses like data URIs and email attachments — with practical examples.
Networking · 5 min readCIDR & Subnets Explained
Understand CIDR notation, subnet masks, network and broadcast addresses, and how to calculate how many hosts a subnet holds.
PDF · 3 min readHow to Merge PDF Files
Learn how to combine multiple PDFs into one file for free, in your browser, without uploading anything — plus how to reorder and split them again.
PDF · 3 min readHow to Reduce PDF File Size
Learn why PDFs get large and how to compress one to fit an email or upload limit — what actually shrinks a file and the trade-offs to know.
PDF · 3 min readHow to Convert a PDF to Word
Learn how to turn a PDF into an editable Word document and convert Word back to PDF — what converts cleanly, what doesn't, and why layout is hard.
Email · 5 min readSPF, DKIM and DMARC Explained
What SPF, DKIM and DMARC actually do, how they work together to stop email spoofing, and the order to set them up — in plain English.
Email · 4 min readWhy Is My Email Going to Spam?
The real reasons legitimate email lands in spam — mostly authentication — and a practical checklist to fix deliverability and reach the inbox.
Email · 4 min readHow to Set Up DMARC
A safe, step-by-step DMARC rollout: start at p=none, read the reports, then move to quarantine and reject — without blocking your own email.
Email · 4 min readWhat Is an SPF Record?
What an SPF record is, how to read one, the mechanisms like -all and ~all, and the 10-DNS-lookup limit that silently breaks SPF.
Email · 4 min readHow to Read Email Headers
Learn how to find and read the raw headers of an email — trace its delivery path, spot delays, and check whether it's authentic or spoofed.
Text · 3 min readWords vs Characters: How to Count Them
The difference between counting words and characters, rough conversions, and where each limit matters — from essays to tweets to SEO tags.
SEO · 3 min readWhat Is Keyword Density?
What keyword density means, why chasing a magic percentage backfires, and how to use it to write focused content without keyword stuffing.
Text · 4 min readMarkdown Syntax Guide
A concise Markdown cheat sheet: headings, bold, lists, links, images, code and tables — with examples you can try in a live editor.
SEO · 3 min readWhat Is a Meta Description?
What a meta description is, the ideal length, whether it affects rankings, and how to write one that earns clicks from search results.
SEO · 3 min readrobots.txt Explained
What a robots.txt file controls, how allow and disallow rules work, and the crucial thing it does NOT do — keep a page out of Google.
SEO · 3 min readWhat Is a Canonical URL?
What a canonical URL is, how rel=canonical prevents duplicate-content problems, and how to check yours is self-referencing and correct.
SEO · 4 min readOpen Graph & Twitter Cards Explained
How Open Graph and Twitter Card tags control the preview when your links are shared, the image sizes to use, and why your preview may be blank.
SEO · 3 min readHow to Minify CSS, JS and HTML
What minification does, how much it saves, why it speeds up your site and helps Core Web Vitals, and how to minify each asset type safely.
Networking · 4 min readWhat Is a CSR (Certificate Signing Request)?
Understand what a CSR is, what's inside it, how it relates to your private key, and how to decode and check one before you order an SSL certificate.
Networking · 4 min readHow to Check If a Domain Name Is Available
Learn how to check whether a domain name is available to register, what to do if it's taken, and how WHOIS and DNS help you research a domain.
Developer · 4 min readHow to Compare Two JSON Files (JSON Diff)
Learn how to compare two JSON files or objects and spot exactly what changed — added, removed and modified keys — with a JSON diff tool.
Networking · 3 min readWiFi QR Codes: Share Your Network Instantly
Learn how a WiFi QR code works, how guests connect by scanning it, and how to generate one for your network — no more reading out long passwords.
Student · 4 min readHow to Calculate CGPA (and Convert It to Percentage)
Understand how CGPA is calculated from your semester SGPAs and credits, and how to convert a CGPA to a percentage using your university's formula.
Finance · 4 min readHow to Calculate EMI on a Loan
Learn how loan EMI is calculated, what raises or lowers it, how much of it is interest, and how prepayment and tenure change the total you pay.
Finance · 4 min readWhat Is a SIP (and How Its Returns Work)
Understand what a SIP is, how rupee-cost averaging and compounding grow your investment, how SIP returns are calculated, and how a SIP compares to a lumpsum.
Image · 3 min readHow to Compress an Image Without Losing Quality
Learn why image files get big, how lossy compression works, the quality sweet spot, and how to shrink a photo for email or the web without visible loss.
Generators · 3 min readHow to Create a QR Code
Learn what QR codes can hold, how to create one for a URL, WiFi network or UPI payment, and the best practices for a code that always scans.
AI · 4 min readHow to Estimate LLM API Costs (Claude, OpenAI, Gemini)
Understand how LLM API pricing works — input vs output tokens, per-million rates and caching — and how to estimate the cost of a Claude, OpenAI or Gemini call.
Finance · 4 min readHow to Calculate In-Hand Salary from CTC
Understand why your in-hand salary is lower than your CTC, which components are deducted, and how to work out your real monthly take-home pay.
PDF · 3 min readHow to Rotate a PDF and Save It Permanently
Learn why a rotated PDF often reverts, and how to rotate pages and save the change permanently so the file opens the right way up everywhere.