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Open source
24 alternativesSubDomainizer
SubDomainizer searches web pages, folders, and JavaScript files for subdomains and related information.
About SubDomainizer
SubDomainizer is an open-source Python tool that searches a webpage, its external JavaScript files, GitHub, or a local folder for hidden subdomains and related information. Alongside subdomains, it extracts URLs for cloud storage services such as Amazon AWS (CloudFront and S3 buckets), DigitalOcean Spaces, Microsoft Azure, Google Cloud Services, Dreamhost and RackCDN, and it can look for secrets in page and JavaScript content.
Version 3.0 is rewritten as a modular Python package that can also be used programmatically through Scanner, ScanConfig and ScanResult. Passive subdomain enumeration queries crt.sh, the Wayback Machine and HudsonRock Cavalier on every scan, and results can be printed as JSON or written to separate files for subdomains, cloud service URLs and secrets. Secret finding is in beta: it depends on specific keywords and the Shannon Entropy formula with false-positive filtering, so some findings may be false positives. GitHub scanning requires a GitHub API token.
Key features
- Finds hidden subdomains in webpages, external JavaScript files, GitHub and folders
- Detects cloud storage URLs including S3, CloudFront, Azure, Google Cloud, DigitalOcean Spaces, Dreamhost, RackCDN
- Beta secrets detection using keywords and Shannon entropy with false-positive filtering
- Passive enumeration via crt.sh, Wayback Machine and HudsonRock Cavalier on every scan
- Programmatic Python API using Scanner, ScanConfig and ScanResult
- JSON output plus separate output files for subdomains, cloud URLs and secrets
Best for: Security researchers, penetration testers and bug bounty hunters looking for hidden subdomains, cloud storage endpoints and exposed secrets in web content and JavaScript.
Good for
- Open-source Python package that can be used from the command line or imported as a library
- Covers multiple cloud storage services and can scan GitHub or a local folder
- Structured JSON output and dedicated output files for subdomains, cloud URLs and secrets
Watch out for
- Secret key searching is in beta and may report false positives
- GitHub scanning requires a GitHub API token
SubDomainizer at a glance
- Category
- Development › Domain, IP & DNS Lookup
- Type
- Open-source project
- Pricing
- Not confirmed. Check the site
- Open source
- Yes · Source code
- Language
- English
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
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SubDomainizer FAQ
Do I need a GitHub token to scan GitHub?
Yes. The -gt / --gittoken GitHub API token is required when GitHub scanning is enabled with -g.
What do the Subject Alternative Name options do?
-san all finds all domains and subdomains from TLS certificates; -san same finds only subdomains belonging to the same TLD.
How reliable is the secrets detection?
It is a beta feature that relies on specific keywords and the Shannon Entropy formula with false-positive filtering; some secrets the tool reports may be false positives.
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