Fact-check YouTube claims without leaving the video.

Press the check button, pick the claim you care about, and read a source-backed verdict while the video stays right where it is.

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Desktop Chrome only. Free to install. No credit card required.

See the extension working.

Four steps. Zero tab-switching.

The interactive demo lives here, but WasThatTrue is a desktop Chrome extension. Open this page on a laptop to see it in action.

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This is interactive, give it a try!

youtube.com/watch?v=xK29jR8m

“...the Amazon rainforest stores 150 billion tonnes of carbon, produces twenty percent of the world's oxygen, and we're losing a football pitch of it every six seconds.”

14:32 / 38:17

You hear something that sounds off. The speaker is making a bold claim mid-video. You do not have to open a new tab or remember to check it later.

The extension reads what was just said. It pulls the factual claims out of the last few seconds of captions. No credit has been spent yet.

You decide what gets checked. Pick one claim, pick a few, or skip the ones you already trust. A credit is only spent when you verify.

The verdict appears, right there. Verdict, confidence, explanation, and sources sit beside the video without stealing your place.

Built for honest answers, not engagement.

No algorithm decides what gets checked. No black box decides the verdict.

You trigger it. Not us.

Nothing is checked automatically. There is no passive surveillance of what you watch. You decide what warrants scrutiny, every time.

Primary sources, cited.

Every verdict links directly to peer-reviewed studies, government data, and established institutions. You can read the evidence yourself, always.

Honest about uncertainty.

Contested claims are labelled Contested. Unverifiable claims are labelled Unverifiable. We don't force certainty where none exists. Doubt is a real answer.

No spin. Four honest labels.

The evidence determines the verdict, not the narrative.

True

Supported by evidence

The claim is corroborated by peer-reviewed studies or primary sources with high confidence.

False

Contradicted by evidence

The claim is directly refuted by credible, verified sources. The sources are listed so you can read them.

Contested

Genuine expert disagreement

Credible studies exist on multiple sides. We label it contested and show both positions, not a forced verdict.

Unverifiable

Cannot be confirmed

No credible evidence exists to confirm or deny the claim. We tell you that, rather than guessing.

Turn a fact-check into a YouTube comment.

One click copies it as a ready-to-paste comment: timestamped, quoted, and sourced. You decide whether to post it.

FalseHigh confidence

"the Great Wall of China is the only man-made structure you can see from space"

Claim · The Great Wall of China is visible to the naked eye from space.

China's Wall Less Great in View from Space · NASA · 2005Is China's Great Wall Visible from Space? · Scientific American · 2008

Comments

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Clickable timestampThe comment opens with the moment the claim was made. On YouTube it becomes a tap-to-seek link.
Sources by nameEvery source is cited by publication and headline, so readers can look it up and judge it themselves.
No linksYouTube tends to hide comments that contain links. The copied text carries none, so it is more likely to stay visible.

“Built to combat misinformation in the age of post-truth politics.”

In an age of deepfakes and deliberate attempts to pollute our information landscape, the responsibility falls upon each of us to fact-check what we consume.

YouTube is the world's second-largest search engine. Billions of people form their beliefs about vaccines, climate, economics, and politics from what they watch.

WasThatTrue gives those viewers a tool, not an opinion. Honest about what the evidence says. Honest about when it doesn't.

Stop wondering.
Check the claim.

Add WasThatTrue to Chrome and get source-backed verdicts on YouTube, right where the claim was made.

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