Domain Availability Checker

A production-ready Python script for bulk domain availability checking using WHOIS, DNS, and HTTP fallback methods.

How to Run

1. Install dependencies:

pip install -r requirements.txt

2. Run the script:

python domain_checker.py -i domains.txt -o results.csv

Usage Examples

Basic Usage

# Check domains from text file
python domain_checker.py -i domains.txt -o results.csv

# Check with higher concurrency
python domain_checker.py -i domains.txt -o results.csv -c 10

# Enable HTTP fallback for better accuracy
python domain_checker.py -i domains.txt -o results.csv --http-fallback

# Verbose output for debugging
python domain_checker.py -i domains.txt -o results.csv -v

# Quiet mode (minimal output)
python domain_checker.py -i domains.txt -o results.csv -q

Advanced Usage

# Full configuration
python domain_checker.py \
    -i domains.csv \
    -o availability_report.csv \
    -c 8 \
    --whois-timeout 45 \
    --dns-timeout 15 \
    --retries 5 \
    --rate-limit-delay 2.0 \
    --http-fallback \
    --verbose

Sample Input

domain-12345.com
google.com
github.com

Sample Output

Console Output

============================================================
DOMAIN AVAILABILITY CHECKER
============================================================
Input file:         domains.txt
Output file:        results.csv
Domains to check:   7
Concurrency:        5
WHOIS timeout:      30s
DNS fallback:       Enabled
HTTP fallback:      Disabled
Rate limiting:      Enabled
============================================================

Checking domains: 100%|████████████████| 7/7 [00:15<00:00,  2.14s/domain]

============================================================
DOMAIN AVAILABILITY CHECK SUMMARY
============================================================
Total domains checked:  7
✅ Available:              2 (28.6%)
❌ Registered:             5 (71.4%)
❓ Unknown:                0 (0.0%)
⚠️ Errors:                 0 (0.0%)
============================================================

✅ AVAILABLE DOMAINS:
  ✓ example-test-domain-12345.com
  ✓ this-domain-is-probably-available-xyz123.net

Time elapsed: 15.23 seconds
Average: 2.18 seconds per domain

CSV Output

domain	status	registrar	expiry_date	creation_date	notes	check_method	checked_at
domain-12345.com	Available				Domain is available	WHOIS	2025-12-13T22:56:02.624428+00:00
google.com	Registered	MarkMonitor Inc.	2028-09-14	1997-09-15	Domain is registered	WHOIS	2025-12-13T22:56:02.624942+00:00
github.com	Registered	MarkMonitor Inc.	2026-10-09	2007-10-09	Domain is registered	WHOIS	2025-12-13T22:56:02.624982+00:00

Architecture Diagram

┌────────────────────────────────────────────────────────────────┐
│                     DomainChecker (Orchestrator)               │
├────────────────────────────────────────────────────────────────┤
│  ┌──────────────┐   ┌──────────────┐   ┌──────────────┐        │
│  │   Semaphore  │   │ Rate Limiter │   │Thread Pool   │        │
│  │ (Concurrency)│   │  (Per TLD)   │   │  Executor    │        │
│  └──────────────┘   └──────────────┘   └──────────────┘        │
├────────────────────────────────────────────────────────────────┤
│                         Check Pipeline                         │
│  ┌──────────────┐   ┌──────────────┐   ┌──────────────┐        │
│  │    WHOIS     │──▶│    DNS       │──▶│    HTTP     │        │
│  │   Checker    │   │  Fallback    │   │  Fallback    │        │
│  │  (Primary)   │   │ (Secondary)  │   │ (Tertiary)   │        │
│  └──────────────┘   └──────────────┘   └──────────────┘        │
└────────────────────────────────────────────────────────────────┘
                              │
                              ▼
                    ┌──────────────────┐
                    │   DomainResult   │
                    │  - domain        │
                    │  - status        │
                    │  - registrar     │
                    │  - expiry_date   │
                    │  - notes         │
                    └──────────────────┘

Key Features

Feature	Description
Async I/O	Uses asyncio for concurrent domain checking
Rate Limiting	Per-TLD rate limiting to avoid WHOIS blocking
Retry Logic	Automatic retries with exponential backoff
Multiple TLDs	Supports .com, .net, .org, ccTLDs, new gTLDs
Fallback Methods	DNS and HTTP checks when WHOIS fails
Pattern Matching	Robust detection of "available" vs "registered"
Progress Display	Real-time progress with tqdm (optional)
CSV Export	Detailed results for further analysis

Dependencies

python-whois>=0.8.0
aiohttp>=3.9.0
dnspython>=2.4.0
tqdm>=4.66.0  # Optional, for progress bar