Fact-check an AI answer before you use it
AI states made-up numbers, quotes and sources as calmly as real ones. Paste an answer and get a checklist of every detail worth checking, the riskiest first, with a search link for each. Nothing you paste leaves this browser.
Read how to fact-check an AI answer, in four steps that take a few minutes.
New to this? What it does, in plain words
It finds every sentence in an AI answer that states something you could check, and turns them into a checklist.
Use it before an AI answer goes into a report, a client email, a slide or a policy. A consultant can check the statistics in a market summary. An HR manager can check the law an answer quotes. A student can find the references that need looking up.
What you need
Nothing. No API key, no sign-up. The checklist is built in this browser. When you press a search link, that search goes to the site you chose, as any search does.
How to use it
- Paste the AI answer. The checklist appears as you paste.
- Work down the list. Each item says what kind of detail it is and why it is worth checking, with links to search for it.
- Mark each one Correct or Wrong as you go.
- Then ask an AI with web search to verify the rest, or to rewrite the answer keeping only what you confirmed.
The AI answer
What to check
Paste an answer to see what to check. Numbers, dates, quotes, sources, links, laws and court cases are all picked out.
Ask an AI to check them
Works best in an AI that searches the web, such as ChatGPT with search on or Perplexity. It asks for a source for every claim and tells the AI not to guess.
Rewrite with only what you checked
Keeps what you marked Correct, drops what you marked Wrong, and flags the rest with [check], without adding new facts.
Why AI answers need checking
Models write the most likely next words, not looked-up facts. When they do not know a number or a source, they often produce one that looks exactly right.
- Free, in your browser. Paste the answerFrom any AI, any length.
- Free, in your browser. Get the checklistEvery checkable detail, riskiest first, with why it matters.Instant
- Free, in your browser. Check and markSearch links for each item. Mark it Correct or Wrong.
- You, or an AI with search. Verify the restA prompt that asks an AI with web search for a source for each claim.
- You, or an AI with search. Rewrite safelyKeep what you confirmed, drop what was wrong, flag the rest.
What it picks out
- Check first. Quotes, studies and reports, links, paper references and court cases. These are the details AI invents most often, and the ones that cause the most trouble when they are wrong. Hundreds of court filings have cited cases that do not exist, and large consulting firms have had to correct reports with invented quotes and references.
- Worth checking. Statistics, money amounts and percentages, laws and section numbers, people and their job titles, and claims that something is the first, the largest or the only one.
- Quick check. Dates and years, and vague authority such as “studies show” or “experts agree”, which cannot be checked until someone names the source.
It never says “true”
This tool finds what is worth checking. It does not decide whether a claim is right, because no set of rules can. A search link opens a search, and only you, or a source you trust, can confirm the answer. Asking the same AI “are you sure?” is not a check: it will often agree with itself, or change a right answer to a wrong one.
Fewer made-up facts to begin with
Give the AI the material to work from, ask it to say when it does not know, and ask for sources it can quote from what you gave it. The guide How to reduce made-up answers covers the prompts that help most.
Questions
Is my text uploaded anywhere?
No. The checklist is built in this browser, and nothing you paste is sent to thinkhard.si or anyone else. A search link sends only that search to the site it opens, and only when you press it. Your text and your marks are kept in this browser so they survive a reload, and Clear removes them.
Why is a sentence on the list when it is obviously true?
The list is built from what a sentence contains, such as a number or a named source, not from whether it is likely to be right. A quick look is usually enough for those. Mark them Correct and move on.
Can it check the links for me?
A web page cannot open another site’s pages in the background to see whether they exist, and a link that works can still say something different from the answer. Open each link, check it loads and that it says what the answer claims.
Does it work for references in essays and papers?
Yes. Paper references with a DOI get a direct link to the paper, and named studies get a Google Scholar search. Check the paper exists, that the authors and year match, and that it says what the text claims it says.