# Verfiai > Free research and claim-level evidence checking. Verfiai shows the sources behind each finding; it is a review aid, not an infallible truth engine. Verfiai is free for everyone during the community period, with fair-use limits. Most tools run in the visitor's browser; tools that consult public registries (Crossref, PubMed, arXiv, ORCID, Open Library, Internet Archive and others) say so on their page. ## Core product - [Fact checker](https://verfiai.app/fact-checker): Check a single claim against cited web and scholarly evidence. - [Research reports](https://verfiai.app/research): Generate a cited research report (sign-in required). - [Citation checker](https://verfiai.app/tools/citation-checker): Verify references against Crossref. - [Methodology](https://verfiai.app/methodology): How evidence is gathered, ranked and labeled. - [Accuracy](https://verfiai.app/accuracy): Known limits of automated checking. ## Free tools - [DOAJ Journal Checker](https://verfiai.app/tools/doaj-journal-checker): Check whether a journal or article is indexed in the Directory of Open Access Journals. - [Semantic Scholar Search](https://verfiai.app/tools/semantic-scholar): Look up scholarly papers and authors with citations, year, venue, and open-access links. - [OpenCitations DOI Explorer](https://verfiai.app/tools/opencitations): Explore inbound citations and references for a DOI using OpenCitations. - [Dataset & DOI Finder](https://verfiai.app/tools/zenodo-finder): Search Zenodo datasets and resolve DOI metadata through DataCite. - [DNS Inspector](https://verfiai.app/tools/dns-inspector): Inspect public A, AAAA, MX, TXT, NS, CNAME, and SOA DNS records. - [Certificate Explorer](https://verfiai.app/tools/certificate-explorer): Review public TLS certificate history, issuers, dates, and discovered subdomains. - [Phone Number Verifier](https://verfiai.app/tools/phone-verifier): Parse and validate phone numbers locally, with country, type, and E.164 format. - [Unit Converter](https://verfiai.app/tools/unit-converter): Convert length, weight, temperature, speed, area, volume, and data size offline. - [Currency Converter](https://verfiai.app/tools/currency-converter): Convert currencies with free public Frankfurter rates, including historical dates. - [Percentage Calculator](https://verfiai.app/tools/percentage-calculator): Calculate a percentage of a value, percentage share, or percentage change. - [Calculator](https://verfiai.app/tools/calculator): A basic arithmetic calculator with keyboard support. - [Age & Date Calculator](https://verfiai.app/tools/age-date-calculator): Calculate age, days between dates, or add and subtract calendar days. - [IP Address Checker](https://verfiai.app/tools/ip-checker): Check your public IP or look up an IP address, location, organization, and ASN. - [Flashcard Maker](https://verfiai.app/tools/flashcards): Create private flashcard decks and review, shuffle, and track known cards locally. - [Stopwatch & Timer](https://verfiai.app/tools/stopwatch-timer): Use a stopwatch with laps or a visual countdown timer. - [Scratch Notes](https://verfiai.app/tools/scratch-notes): Write private notes with autosave and export them as a text file. - [English Dictionary](https://verfiai.app/tools/dictionary): Find English definitions, parts of speech, synonyms, antonyms, and pronunciation. - [Free Translator](https://verfiai.app/tools/translator): Translate text with your device's built-in translator or the free MyMemory API. - [Transcript Translator](https://verfiai.app/tools/transcript-translator): Translate a transcript locally when available or with a free keyless API, side by side. - [No-AI Text Summarizer](https://verfiai.app/tools/no-ai-summarizer): Select key sentences using word frequency. No AI; see every selected sentence. - [Word Frequency & N-gram Counter](https://verfiai.app/tools/word-frequency): Find frequent words and phrases with an optional stopword filter. - [Regex Tester](https://verfiai.app/tools/regex-tester): Test a regular expression live and explore common pattern examples. - [Cron Expression Explainer](https://verfiai.app/tools/cron-explainer): Explain common five-field cron schedules and preview upcoming run times. - [Unit Converter](https://verfiai.app/tools/unit-converter): Convert length, weight, temperature, data size, and speed in your browser. - [Color Contrast Checker](https://verfiai.app/tools/color-contrast): Check WCAG contrast ratios and AA/AAA text accessibility thresholds. - [Image Compressor & Resizer](https://verfiai.app/tools/image-compressor): Compress or resize JPG, PNG, and WebP images locally in your browser. - [QR Code Scanner](https://verfiai.app/tools/qr-scanner): Read a QR code from an image or camera in your browser. - [Image Text Extractor (OCR)](https://verfiai.app/tools/image-ocr): Extract text from an image on-device with a lazily loaded OCR engine. - [Acronym Extractor](https://verfiai.app/tools/acronym-extractor): Find likely acronyms in text and show their surrounding context. - [Date & Deadline Calculator](https://verfiai.app/tools/date-calculator): Calculate days between dates, weekdays, and future deadlines. - [Encode, Decode & SHA-256](https://verfiai.app/tools/encode-hash): Encode Base64 or URL text and calculate a SHA-256 text digest locally. - [SRT Subtitle Timing Shifter](https://verfiai.app/tools/srt-shifter): Shift subtitle timestamps by a fixed offset and correct SRT timing format. - [Polling Margin of Error Calculator](https://verfiai.app/tools/margin-of-error): Estimate a poll's margin of error from its sample size and proportion. - [Citation Reference Checker](https://verfiai.app/tools/citation-checker): Free with a Verfiai sign-in: check references for metadata, retraction notices, and citation risks. - [Wikipedia Article Citation Formatter](https://verfiai.app/tools/wikipedia-citations): Look up a Wikipedia article and format a basic citation from its metadata. - [Wikidata Entity Lookup](https://verfiai.app/tools/wikidata-lookup): Search Wikidata for entity labels, descriptions, and item identifiers. - [Currency Converter](https://verfiai.app/tools/currency-converter): Convert currencies using free European Central Bank reference rates. - [Open Access Paper Finder](https://verfiai.app/tools/open-access-finder): Check OpenAlex and Unpaywall for a legal open-access copy of a DOI. - [Scholarly Works Search](https://verfiai.app/tools/scholar-search): Search OpenAlex for scholarly works; results are cached per query this session. - [Europe PMC Open Access Reader](https://verfiai.app/tools/europepmc-reader): Find biomedical articles and open available full text from Europe PMC. - [bioRxiv & medRxiv Preprint Finder](https://verfiai.app/tools/preprint-finder): Search recent bioRxiv and medRxiv metadata from their public APIs. - [GDELT News Coverage Search](https://verfiai.app/tools/gdelt-news): Search GDELT's public news index with a single paced request per search. - [SEC Filings Full-Text Search](https://verfiai.app/tools/sec-filings): Search SEC EDGAR filing text for public company disclosures. - [World Bank Data Lookup](https://verfiai.app/tools/world-bank-data): Look up official country statistics using World Bank indicator codes. - [Google Fact Check Explorer](https://verfiai.app/tools/factcheck-explorer): Opens an external free tool: a prefilled Google Fact Check Explorer search. - [InVID-WeVerify Video Verification](https://verfiai.app/tools/video-verify): Opens an external free tool: the InVID-WeVerify verification toolkit guide. - [Image Forensics Tools](https://verfiai.app/tools/image-forensics): Opens external free tools: FotoForensics and Forensically image checks. - [Connected Papers](https://verfiai.app/tools/connected-papers): Opens an external free tool: a paper title search on Connected Papers. - [Google Scholar Search](https://verfiai.app/tools/google-scholar): Opens an external free tool: a title or author search in Google Scholar. ## Guides - [Video Research](https://verfiai.app/video-research): A practical guide to researching video transcripts, quotes, publishers, and original uploads. - [How to Check: Verification Questions & Answers](https://verfiai.app/how-to-check): Practical answers to common questions about checking photos, sources, quotes, and online claims. - [Free Research Templates & Verification Guides](https://verfiai.app/templates): Download checklists and logs for claims, evidence, citations, and compliance. ## Optional - [Glossary](https://verfiai.app/glossary): Research and fact-checking terms. - [Sources directory](https://verfiai.app/sources): Informational catalog of sources. - [All tools](https://verfiai.app/tools): Categorized hub.