I recently found myself needing to buy a short, brandable domain for a side project. I spent hours typing names into GoDaddy, only to get frustrated by the slow interface and the constant upsells.
As a developer, I thought: "Why not just query the RDAP registries directly and score the domains algorithmically?"
So I built a free tool to do exactly that. Here is how it works and why RDAP is the future of domain checking.
The Problem with Traditional WHOIS
Most domain tools still use standard WHOIS (Port 43). It is plain text, rate-limits aggressively, and often gets blocked by registrars.
RDAP (Registration Data Access Protocol) is the modern, ICANN-mandated replacement. It returns structured JSON and uses standard HTTPS status codes:
200 OK = Domain is registered.
404 Not Found = Domain is available.
This makes it incredibly easy for developers to query concurrently without getting blocked.
The Architecture
I built a tool that lets you paste up to 50 domains (one per line). Instead of firing 50 requests at once and getting rate-limited, the backend processes them in small concurrent batches (using curl_multi in PHP).
Here is what the result dashboard looks like:
The Domain Scoring Algorithm
Just knowing if a domain is available isn't enough. You need to know if it's actually good.
I wrote an algorithmic scoring system (0-100) that evaluates domains across 5 dimensions:
Extension (TLD): .com, .ai, .io score highest.
Length: Short names (4-5 letters) get exponential value.
Pronounceability: It analyzes vowel-consonant patterns (CVCV) to ensure it's easy to say.
Meaning: Checks against a built-in dictionary of common English words.
Brand Fit: Looks for industry prefixes like AI, tech, or e-commerce.
If a domain scores 80+, it's highlighted in red as a 🔥 High Value domain. You can copy all the high-value results to your clipboard with one click.
Why I Made It Free (For Now)
I'm currently offering single checks for free. Building this has taught me a lot about RDAP and concurrent API handling.
If you want to try it out, you can check it here:
👉 Site Tools Box - Domain Availability Check
(Note: The bulk check feature is currently locked behind a Pro tier while I optimize the server load, but single checks are 100% free).
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