DEV Community: Muhammad Asad Arshad

20 Free, No-Signup Web Tools Every Developer Should Bookmark

Muhammad Asad Arshad — Thu, 16 Jul 2026 07:33:44 +0000

20 Free, No-Signup Web Tools Every Developer Should Bookmark fastestchecker.com
Every dev has a mental list of "quick check" sites they reach for what's my IP, is this JSON valid, how big is this image after I resize it. The annoying part is that half of them make you sign up, sit through an ad-gated redirect, or upload your data to some sketchy server just to run a client-side operation that could've happened in your browser.
I put together a list of the tools I actually keep bookmarked, mostly pulled together in one place at FastestChecker.com — free, no account required, and most of it runs client-side. Sharing the breakdown by category in case it saves someone else a few tabs.
Network & Domain Tools

IP Checker — your current public IPv4/IPv6 address, useful for confirming what your server or API actually sees behind a proxy.
Website Location Checker — find out where a site is actually hosted, handy when you're debugging latency or picking a region for your own deployment.
Domain Age Checker — quick way to sanity-check a domain's history before you trust a link or evaluate a backlink source.
Internet Speed Test — no flash, no forced app install, just a straight bandwidth check.

Security & Dev Utilities

Password Generator — configurable length/character sets, generated client-side so nothing gets transmitted.
Email Validator — syntax + MX record checks in one click (I wrote up how this actually works under the hood [in a separate post — PASTE YOUR EMAIL-VALIDATION POST URL HERE] if you want the technical breakdown).
JWT Decoder — paste a token, read the header/payload without pasting your auth token into a random site you don't trust.
Test Card Generator — Luhn-valid dummy card numbers for Stripe/PayPal sandbox testing. Not real cards, just structurally valid test data.

Text & Content Tools

Word Counter — words, characters, reading time — the basics done fast.
Text Case Converter — camelCase, snake_case, PascalCase, Title Case, all in one place.
Markdown Editor — live preview, no account, useful for drafting a README before you commit it.
Text Extractor / OCR — pull text out of a screenshot instead of retyping an error message from an image.
QR, Barcode & Image Tools
QR Code Generator — including Wi-Fi QR codes, which is a nice trick for office setups.
Barcode Generator — UPC/EAN generation for small projects that need one without a full POS system.
Image Resizer — resize without a Photoshop round trip.
Image Color Picker — grab a hex code straight from a screenshot or reference image.

Website & SEO Analysis

Traffic Checker rough traffic estimates for competitor research.
PageSpeed Checker Core Web Vitals without digging through the full Search Console UI.

A Couple Extras

Loan Calculator — not dev-related, but useful enough to mention.
Stylish Name Generator — mostly for gaming handles, but occasionally handy for generating placeholder usernames in test data.

Why This List Instead of Individual Sites
Nothing here is doing something no other tool does — the value is just not needing 15 different tabs, accounts, and ad-walls to do routine checks. If you already have a favorite tool for one of these, no argument from me. But if you're missing one of these from your bookmarks bar, FastestChecker.com is worth a look.
FAQ
Do any of these tools require an account?
No everything on the list runs without sign-up, and most operations (password generation, text conversion, image resizing) happen client-side, so your data isn't sent anywhere to process it.
Is this free to use, or is there a paid tier?
Free, ad-supported. No feature paywalls on the core tools.
Which of these tools is most useful for backend debugging specifically?
The IP Checker and JWT Decoder get the most day-to-day use for debugging auth and networking issues — both let you inspect exactly what's being sent/received without spinning up extra tooling.

How to Verify an Email Is Real Without Sending One (Dev Guide) Published

Muhammad Asad Arshad — Thu, 16 Jul 2026 07:02:23 +0000

How to Verify an Email Address Is Real Without Sending One

A regex that checks for an @ and a . will happily accept test@thisdoesnotexist12345.com. It's syntactically valid — and completely useless. If you're building a signup form, a lead capture flow, or anything that emails users, "looks like an email" and "is a deliverable email" are two very different checks, and conflating them is how you end up with a database full of bounced addresses.
This post walks through the actual layers of email verification, what each one catches, and where each one breaks down.
TL;DR
Email verification happens in layers, each one more expensive and less reliable than the last:
_
**_Syntax check — does it look like an email? (cheap, catches typos)**
Domain/MX check — can this domain even receive mail? (catches fake domains)
SMTP handshake — does this specific mailbox exist? (catches typos in the username, but unreliable — many providers block it)
Disposable/catch-all detection — is this a throwaway address or a domain that accepts everything? (catches abuse)
For a quick manual check without writing any code, FastestChecker's Email Validator runs through these layers for you.
Layer 1: Syntax Validation
This is the bare minimum — confirming the string is shaped like an email address.

javascriptfunction isValidSyntax(email) {
  const regex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return regex.test(email);
}

Don't reach for an exhaustive RFC 5322-compliant regex here — it's notoriously long, hard to maintain, and still won't tell you if the address is deliverable. A simple pattern that catches obvious mistakes (missing @, no domain, no TLD) is enough at this layer. The real verification work happens next.

*Layer 2: Does the Domain Even Accept Mail?
*
This is the layer most signup forms skip, and it's the one that catches the most fake submissions. Every domain that can receive email publishes an MX (Mail Exchange) record in DNS. If there's no MX record, no mail is getting delivered there — full stop.

Node.js

javascriptconst dns = require('dns').promises;

async function hasMxRecord(email) {
  const domain = email.split('@')[1];
  try {
    const records = await dns.resolveMx(domain);
    return records.length > 0;
  } catch {
    return false; // No MX record = domain can't receive mail
  }
}

Python

pythonimport dns.resolver

def has_mx_record(email):
    domain = email.split('@')[1]
    try:
        records = dns.resolver.resolve(domain, 'MX')
        return len(records) > 0
    except Exception:
        return False

This single check eliminates most typo'd domains (gmial.com, yaho.com) and made-up ones — with zero risk of tipping off the mail server that you're probing it.

Layer 3: SMTP Handshake (Use With Caution)

This is the layer that theoretically checks whether the specific mailbox exists, not just the domain. It works by opening an SMTP connection to the mail server and issuing a RCPT TO command without actually sending a message — the server's response tells you whether it would accept mail for that address.

In practice, this is unreliable:
Gmail, Outlook, and most major providers reject or rate-limit this to prevent exactly this kind of probing.
Greylisting can cause a valid address to temporarily look invalid.
Catch-all domains (common on custom business email setups) will report every address as valid, even ones that don't exist.
Treat SMTP verification as a weak signal at best, not a source of truth. Most production systems either skip it entirely or use a third-party verification API that maintains reputation and IP rotation to avoid getting blocked.

Layer 4: Disposable Email Detection

Services like Mailinator or Temp-Mail let users generate throwaway addresses that pass every check above but exist only to receive one confirmation email. If you're trying to reduce fake signups (not just bounces), cross-reference the domain against a maintained list of disposable email providers — there are several open-source lists on GitHub you can pull into your validation pipeline.

What Actually Matters for Most Apps

You almost never need all four layers. A practical default:

Signup forms: syntax + MX check. Fast, free, catches 90% of garbage input.
Email marketing lists: add disposable-domain filtering to protect sender reputation and deliverability.
High-value transactional flows (password resets, payment receipts): consider a paid verification API for the SMTP-layer confidence, since a bounced reset email is a real support problem.

What Is My IP Address? IPv4 vs IPv6 Explained for DevelopersPublished

Muhammad Asad Arshad — Thu, 16 Jul 2026 06:46:51 +0000

What Is My IP Address? IPv4 vs IPv6 Explained for Developers
If you've ever debugged a CORS error, set up an IP allowlist, or wondered why req.ip returned something weird in your Express logs, you've run into the same question from a different angle: what actually is an IP address, and which one is "mine"? fastestchecker.com

This post breaks down IPv4 vs IPv6, public vs private IPs, and how to reliably detect a user's IP address in your own code — plus a fast way to check yours right now.fastestchecker.com

TL;DR
IPv4 addresses look like 192.168.1.1 — four numbers, 0-255, separated by dots. There are about 4.3 billion of them, and we've run out.
IPv6 addresses look like 2001:0db8:85a3::8a2e:0370:7334 — a much larger address space designed to replace IPv4.
Your device usually has a private IP (local network) and shares a public IP (internet-facing) with everyone else on your router.
You can check your current public IP instantly with a tool like FastestChecker's IP Checker — useful for confirming what your server or API actually sees.

> IPv4 vs IPv6
: What's the Actual Difference
IPv4
IPv4 has been the backbone of the internet since the 1980s. It's a 32-bit address, which caps the total number of unique addresses at roughly 4.3 billion. Given how many devices are online today, that pool has been effectively exhausted for years — which is why NAT (Network Address Translation) exists: it lets an entire household or office share one public IPv4 address.

Example IPv4: 203.0.113.42

IPv6

IPv6 uses 128-bit addresses, which gives it an address space so large it's effectively unlimited for practical purposes (2^128 addresses). It was designed specifically to solve IPv4 exhaustion, and adoption has been climbing steadily — most major cloud providers and mobile carriers support it by default now.
**
Example IPv6:** 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Quick Comparison

IPv4IPv6Address length32-bit128-bitFormatDotted decimal (192.168.1.1)Hexadecimal, colon-separatedTotal addresses~4.3 billion~340 undecillionNAT required?Usually, yesNo — every device can have a unique public addressAdoptionLegacy, still dominantGrowing, especially on mobile networks

Public IP vs Private IP

This trips up a lot of people building their first networked app:
Private IP — assigned to your device on your local network (home Wi-Fi, office LAN). Ranges like 192.168.x.x, 10.x.x.x, and 172.16.x.x–172.31.x.x are reserved for this and never routed on the public internet.
Public IP the address your router uses to talk to the internet. This is what external servers see when your device makes a request, and it's typically shared across every device on your network via NAT.

If you console.log a request's IP in a local dev environment and see something like ::1 or 127.0.0.1, that's the loopback address — your machine talking to itself.

How to Get a User's IP Address in Your Backend

A common point of confusion: the "IP address" your server sees isn't always the real client IP, especially behind a proxy, load balancer, or CDN (like Cloudflare or an Nginx reverse proxy). Here's how to handle it properly.

Node.js / Express

`javascriptapp.get('/whoami', (req, res) => {
// Direct connection IP
const directIp = req.socket.remoteAddress;

// If behind a proxy/load balancer, check the forwarded header
const forwardedIp = req.headers['x-forwarded-for']?.split(',')[0].trim();

res.json({ ip: forwardedIp || directIp });
});`

X-Forwarded-For can contain a comma-separated list if the request passed through multiple proxies — the first value is generally the original client IP, but treat it as untrusted input unless you control the proxy chain.

*Python / Flask
*

pythonfrom flask import request

@app.route('/whoami')
def whoami():
    ip = request.headers.get('X-Forwarded-For', request.remote_addr)
    return {"ip": ip.split(',')[0].strip()}

A Note on Trust

Never use a client-reported IP for security-critical decisions (like rate limiting or geofencing) without validating it against a trusted proxy layer first. Headers like X-Forwarded-For can be spoofed by the client unless your infrastructure strips and re-sets them at the edge.

Why Developers Actually Need to Check Their IP

A few real scenarios where this matters day to day:

Debugging API allowlists — confirming the exact public IP your server or CI pipeline is making outbound requests from, so you can whitelist it correctly.
Testing geolocation logic — verifying what country/region your current IP resolves to before shipping geo-based features.
VPN/proxy verification — checking that a VPN or proxy is actually masking your IP as expected.
Local network troubleshooting — confirming whether you're getting a private or public address, and whether IPv6 is actually being assigned by your ISP.
For a fast, no-signup way to check this, FastestChecker's IP Checker shows your current public IPv4/IPv6 address, along with basic connection info — handy for a quick sanity check without spinning up a curl command.
If you want to double check via terminal instead:
bashcurl -4 ifconfig.me # Force IPv4
curl -6 ifconfig.me # Force IPv6
FAQ
Does everyone with the same Wi-Fi have the same public IP?
Yes, typically. Devices on the same home or office network share one public IP address via NAT, even though each device has its own private IP internally.
Why do I have both an IPv4 and IPv6 address?
Most modern networks run in "dual-stack" mode, assigning both an IPv4 and IPv6 address so your device can connect either way depending on what the destination server supports.
Can two devices have the same public IP at the same time?
Yes — this is normal for devices behind the same NAT (same home/office network). It's the combination of IP + port that uniquely identifies each connection.
Is my IP address the same as my location?
Roughly — IP-based geolocation is usually accurate to the city or region level, tied to your ISP's registered address blocks, but it's not a precise GPS location.
Auther: Muhammad Asad Arshad
Email: arshadasad566@gmail.com

Webdesign

Muhammad Asad Arshad — Fri, 25 Apr 2025 20:05:54 +0000

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problemSolver:true,
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