Working Towards Building Reliable Fact Checking
Certain is a Chrome extension that checks claims against primary sources and shows you exactly how it reached its verdict. It's the first step towards our goal: the most reliable fact checker available.
We're just getting started
Today, every claim is checked against primary sources with transparent reasoning. Our goal is bigger: to become the most reliable fact checker available. Here's what we're working on.
- Claims already checked by organisations like Full Fact are matched to their published verdict.
- Verdicts rely on official, academic and established sources, and are downgraded when only weak sources exist.
- Our accuracy on claims with known verdicts, updated monthly.
- Corrections log. A public record of verdicts we've corrected.
- A curated list of official and expert sources for each topic.
- For schools and newsrooms. Team plans and an API.
- Confidence you can trust. Confidence levels measured against real results.
AI answers aren't the same as facts
Most fact checking tools ask an AI model and hope it's right. The answer sounds confident, but there's no way to tell where it came from or whether it holds up.
We think a fact check is only as good as the evidence behind it. So Certain ties every claim to primary sources, shows its reasoning and lets you audit the result yourself.
Check a claim in 3 steps
- 1
Send a claim
Check any claim straight from your browser, while you're reading it.
- 2
Find primary sources
Certain looks for the primary sources behind the claim, not summaries or opinions about it.
- 3
See the reasoning
You get a verdict, the sources it rests on and the reasoning that connects them.
Reliability you can check
Primary sources first
Every verdict is tied to primary sources, so it rests on evidence rather than a model's best guess.
Transparent reasoning
We show how each verdict was reached. Nothing hides behind a confident-sounding answer.
Auditable results
Every result can be traced back to its sources and checked. You shouldn't have to take our word for it.
Built where you read
Claims appear in articles, posts and reports, so fact checking belongs in your browser.
Help shape what we build next
Certain is in early access. Try it, tell us what works and what doesn't, and help us build a fact checker people can rely on.
Get started