Domain & Website Search Engines
Find the right search engine for every research task
Domain and website search engines reveal certificates, page scans and the technology behind a site. They help researchers trace site ownership and history. Use crt.sh for certificate logs, URLScan.io for page scans and BuiltWith for technology profiles.
- 20 specialized resourcesAcademic, government, legal, archive and data sources
- 16 research categoriesOrganized by research task, not by brand
- 20 editorially reviewedDocumented desk reviews; others show “Not Yet Rated”
- Research guidesLearn how to search each source effectively
Domain & Website search engines & databases
AlienVault OTX
Domain & WebsiteWorld's largest open threat intelligence community sharing threat indicators and malicious IPs.
Archive-It Search
Domain & WebsiteWeb archiving platform helping over 800 partner institutions harvest and preserve digital records.
BuiltWith
Domain & WebsiteShows the technologies, analytics and hosting used by a website.
Best for: Website technology profiles
Censys Search
Domain & WebsitePublic internet scanning search engine tracking internet infrastructure and cryptographic certificates.
crt.sh
Domain & WebsiteSearch engine for TLS certificates recorded in public certificate transparency logs.
Best for: Certificate transparency logs
DNSDumpster
Domain & WebsiteFree domain research tool discovering subdomains, mail exchangers, and IP hosts.
DomainTools Whois Lookup
Domain & WebsiteLeading cyber intelligence platform for domain profiling, registration data, and IP history.
HackerTarget
Domain & WebsiteSuite of hosted security tools for open-source network reconnaissance and DNS mapping.
Netcraft Site Report
Domain & WebsiteInternet research service analyzing website infrastructure, hosting providers, and risk ratings.
RiskIQ / PassiveTotal
Domain & WebsiteThreat analysis platform providing passive DNS and external digital asset mapping.
Robtex
Domain & WebsitePioneering network and domain analysis tool providing shared IP and DNS graphs.
SecurityTrails
Domain & WebsiteTotal internet data engine indexing historical DNS records and domain infrastructure.
Shodan Search Engine
Domain & WebsitePioneering search engine indexing internet-facing servers, webcams, and network infrastructure.
Spyse Cybersecurity Search
Domain & WebsiteCyber intelligence search engine delivering structured data on digital assets.
Sublist3r Domain Scanner
Domain & WebsiteReconnaissance tool designed to enumerate subdomains of websites using open sources.
URLScan.io
Domain & WebsiteService that scans a URL and records requests, domains, screenshots and technologies.
Best for: Scanning and inspecting web pages
ViewDNS.info
Domain & WebsiteComprehensive suite of domain, DNS, and IP network investigation utilities.
VirusTotal Search
Domain & WebsiteSecurity portal aggregating antivirus engines to inspect domains, URLs, and malicious files.
Whoisology
Domain & WebsiteDomain ownership research database linking millions of domains by registrant email and name.
Whoxy
Domain & WebsiteReverse WHOIS domain research engine maintaining millions of historical WHOIS records.
No resources match these filters.
What is a specialized search engine?
A specialized search engine focuses on one type of content or one subject — scholarly literature, clinical studies, legislation, company filings, archived web pages or official statistics. Its index, metadata and filters are designed for that content, so it often finds sources that general web search engines rank poorly or cannot reach because they sit inside databases.
Example: searching “metformin cardiovascular outcomes” in a general web search engine mixes news and health sites; the same query in PubMed returns indexed clinical literature you can filter by study type and date.
General vs specialized search engines
| Feature | General search engines | Specialized search engines |
|---|---|---|
| Content scope | The open web | One subject or content type |
| Source quality | Mixed; ranked by popularity signals | Curated or authoritative collections |
| Filters | Date, language, file type | Field-specific: study type, court, filing form, dataset |
| Best use | Orientation and general information | Professional, academic and investigative research |
| Examples | Google, Bing | Google Scholar, PubMed, SEC EDGAR, Wayback Machine |
Using AI search for research
AI answer engines can help you frame a question and discover terminology, but they summarize sources and can misstate them. Use them to orient, then confirm facts in a specialized database and cite the original source, not the AI answer.
Browse AI research tools →How AOFIRS reviews resources
Listings are checked against official documentation. Ratings are documented desk reviews scored on seven weighted criteria: usefulness 25%, reliability 20%, features 15%, ease of use 15%, transparency 10%, privacy 10%, value 5%. Defunct, parked and consumer-only sites are removed. Resources without a completed review show “Not Yet Rated”.
Read our editorial policy →Suggest a search engine or report an error
Know a specialized resource we should include, or spotted an outdated detail? Send the resource name, its official website and what should change. AOFIRS does not sell listings or rankings.
Submit a suggestion →How to choose the right search engine
Start from the research task: the type of source you need, who publishes it, and whether you need full text, metadata or raw data. Our guide walks through each research type step by step.
Read the guide →Frequently asked questions
What is a specialized search engine?
A specialized search engine indexes one type of content or one field — for example scholarly papers, court records, company filings, archived web pages or statistical datasets. Because its index and filters are built for that content, it usually returns more relevant, better-sourced results than a general web search engine for professional research tasks.
How is a search engine different from a research database?
A search engine crawls and indexes content from many sources. A research database holds a curated collection, often maintained by a single publisher or agency (PubMed, SEC EDGAR, ERIC). Many resources in this library are search interfaces to databases; each listing states its operator so you know where the data comes from.
Are AI answer engines the same as search engines?
No. AI answer engines such as Perplexity or ChatGPT search generate written answers from retrieved sources. They are useful for orientation, but you should open and check the cited sources. AOFIRS lists AI answer engines separately in the AI Tools section and does not classify every AI product as a search engine.
How does AOFIRS rate search engines?
Ratings are documented desk reviews based on each provider’s official documentation, scored on seven weighted criteria: usefulness 25%, reliability 20%, features 15%, ease of use 15%, transparency 10%, privacy 10% and value 5%. A resource shows “Not Yet Rated” until a review is completed.
Does AOFIRS accept payment for listings?
No. Listings and ratings are editorial. AOFIRS does not sell placement, and resources are not ranked by sponsorship.
How can I report an error or suggest a search engine?
Use the AOFIRS contact page. Include the resource name, its official website and what should change. Corrections are checked against the provider’s own documentation before the listing is updated.
