Learn
Free, structured tutorials on the concepts behind our tools — networking, email, SEO, PDF, AI & agents and more, each as an ordered set of lessons you can work through.
Tutorials
Pick a tutorial and work through it lesson by lesson.
Networking Fundamentals
How the internet finds and connects machines — IP addresses, DNS, subnets, TLS certificates and domains.
Beginner · 5 lessons →✉️Email Deliverability
Keep your email out of spam — SPF, DKIM and DMARC, header analysis and the reasons mail gets filtered.
Intermediate · 5 lessons →🔐Encoding & Auth
The everyday encoding and auth formats developers hit — Base64, JSON Web Tokens and working with JSON.
Beginner · 3 lessons →🔍SEO Essentials
On-page and technical SEO that moves rankings — meta tags, social cards, canonicals, robots.txt, keyword density and minification.
Beginner · 6 lessons →🤖AI Agents & MCP
Build and secure AI agents — LLM costs, MCP server security, and making your own site usable by agents with WebMCP.
Intermediate · 3 lessons →🧠Deep Agents
Build agents for long, multi-step tasks — planning, subagents, a virtual filesystem and tools — with LangChain deepagents, step by step with code.
Intermediate · 9 lessons →📄Working with PDFs
The PDF tasks people do every day — merging, compressing, rotating and converting PDFs, explained.
Beginner · 4 lessons →📝Text & Markdown
Understand word vs character counts and write clean Markdown with confidence.
Beginner · 2 lessons →🧮Everyday Calculators
The finance and student calculations people look up most — CGPA, EMI, SIP returns and in-hand salary.
Beginner · 4 lessons →🖼️Images & QR Codes
Compress images without the quality loss you fear, and generate QR codes — including WiFi QR codes.
Beginner · 3 lessons →Hands-on paths
Guided, step-by-step journeys — learn a concept, then practice it with a live tool.
Networking Fundamentals
Learn how the internet actually works — IP addresses, DNS, subnets and TLS certificates — and practice each concept with a live tool as you go.
Beginner · 4 steps →✉️Email Deliverability
Stop your email landing in spam. A step-by-step path through SPF, DKIM and DMARC, header analysis and deliverability — with tools to check each one.
Intermediate · 5 steps →🔐Encoding & Auth for Developers
The everyday encoding and auth formats every developer hits — Base64, JWTs and JSON — explained clearly, with in-browser tools to decode and inspect them.
Beginner · 3 steps →🤖Build Secure AI Agents (MCP)
Wire up AI agents with MCP without getting burned. Learn tool poisoning, prompt injection and rug-pulls, and vet every server and prompt with free tools.
Intermediate · 4 steps →🔍SEO Essentials
Learn the on-page and technical SEO that actually moves rankings — meta tags, social cards, canonicals, robots.txt and keyword density — with a tool for each.
Beginner · 5 steps →All guides
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.
AI · 7 min readMCP Security: Tool Poisoning, Prompt Injection & Rug-Pulls
How malicious MCP servers attack AI assistants — tool poisoning, prompt injection, hidden unicode and rug-pulls — and how to vet a server before you install it.
AI · 9 min readHow to Make Your Website WebMCP-Ready
A step-by-step guide to WebMCP: expose your site's actions as tools AI agents can call — the declarative form API and the imperative document.modelContext API, with code.
AI · 5 min readWhat Is a Deep Agent?
What a deep agent is: an agent for long, multi-step tasks built on four pillars — planning, a virtual filesystem, subagents and a detailed system prompt.
AI · 4 min readPlanning: the write_todos Pattern
How a deep agent stays on track: the write_todos planning pattern keeps a todo list in the model's attention across long tasks — explained with code.
AI · 4 min readThe Virtual Filesystem
How a deep agent offloads big results and notes to a virtual filesystem so long tasks don't overflow the prompt — and cost less. Explained with examples.
AI · 5 min readSubagents & Context Isolation
A deep agent delegates focused subtasks to specialist subagents, each with its own isolated context. Learn why that improves reliability — with the exact code.
AI · 5 min readWriting the System Prompt
What to put in a deep agent's system prompt — role, workflow, tool use, delegation and guardrails — the part that makes it reliable on hard tasks.
AI · 5 min readGiving Your Agent Tools
How to give a deep agent tools: in deepagents a tool is a plain function whose docstring is its schema — plus how to plug in MCP servers. With code.
AI · 6 min readBuild Your First Deep Agent
Put the four pillars together into a working LangChain deepagents agent — model, tools, a subagent and planning — with a complete, runnable code example.
AI · 5 min readSecuring Deep Agents
A deep agent reads untrusted content, holds secrets and runs many steps — so it needs guardrails. Learn the real risks and how to defend against each.
AI · 5 min readTesting & Debugging Deep Agents
How to verify a deep agent's planning, filesystem and memory actually work — inspect the state, stream the run, trace with LangSmith and unit-test tools.