The best search engine depends on what you need to find. Start with the research task, the kind of source, and how much proof you need. Then pick a tool built for that job.
Start with three questions
What type of source?
Peer-reviewed papers, laws, company filings, datasets, news archives, images or web pages each have specialist indexes.
Who publishes it?
Primary sources from governments, courts, registries and publishers beat copies. Go to the official database when one exists.
What do you need back?
Full text, metadata and citations, raw data, or a quick overview. This decides between an academic index, a data portal or a general engine.
A five-step method
- Define the question. Write one clear sentence and list key terms, synonyms, dates and places.
- Match the source type. Use the category table below to choose two or three specialist engines.
- Search precisely. Use quotes, Boolean operators,
site:,filetype:and date filters. - Check coverage. Note what each engine does not index; repeat key searches in a second engine.
- Verify and record. Open the original source, confirm author and date, and save the link and access date.
Which engine for which task
| Research task | Start with | Browse category |
|---|---|---|
| Scholarly papers and citations | Google Scholar, Semantic Scholar, OpenAlex | Academic |
| Health and clinical evidence | PubMed, Europe PMC, ClinicalTrials.gov | Medical |
| Laws, cases and regulations | CourtListener, EUR-Lex, WorldLII | Legal Research |
| Company and financial records | SEC EDGAR, OpenCorporates, Companies House | Business & Financial |
| Official publications | Congress.gov, GovInfo, Data.gov | Government & Public Records |
| Datasets and statistics | Our World in Data, Google Dataset Search, World Bank | Data & Statistics |
| Archived and deleted pages | Wayback Machine, archive.today | Document & Archive Search |
| PDF documents | Google Advanced Search with filetype:pdf, BASE | PDF Search Engines |
| Private everyday web search | Brave Search, Mojeek, DuckDuckGo | General & Alternative |
| Images, video and audio | TinEye, Openverse, Wikimedia Commons | Image, Video & Audio |
General vs specialist vs AI search
General engines
Fast and broad. Good for orientation and known pages, weaker for paywalled, database or historical content.
Specialist databases
Deep, structured and citable. Best for evidence you will publish or rely on.
AI answer engines
Useful for summaries and leads. Always open each cited source; AI can misstate or invent references. See AI Research Tools.
Red flags when choosing a tool
- No information about what it indexes or how often it updates.
- Results you cannot trace to an original source.
- Downloads offered without clear rights or licensing.
- Heavy tracking or required accounts for basic searches.
Find your search engine
Every resource in the AOFIRS Search Engine Library is rated on seven weighted criteria from official documentation.
Browse the Search Engine LibraryCompare research tools
