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Tardigrade is presented by its creator, Digital Ghost, as a free browser-based auditor: enter a URL to see page weight, an estimated carbon footprint per visit, and an A–F grade. Its results are estimates based on PageSpeed Insights data and a disclosed scoring formula—not direct measurements of the electricity or emissions caused by a particular visit. The creator’s DEV Community post invites developers to try the demo and comment on the scoring, carbon model, and usability: Digital Ghost’s post on DEV Community.
What Tardigrade reports
Digital Ghost describes a simple workflow: submit a URL, review an overall A–F grade, then inspect color-coded performance metrics and suggestions. The listed inputs are page weight, HTTP request count, load time, and Lighthouse score. The author’s short description of the experience is “Paste, read, leave.”
The creator says Tardigrade fetches performance data from Google PageSpeed Insights, then calculates an estimated carbon figure and combines multiple measures into its grade. The post describes a browser-based tool with no account requirement. The live demo’s current availability and behavior have not been independently confirmed, so these are the creator’s descriptions rather than a current audit of the service.
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How its carbon estimate works—and what it does not measure
Digital Ghost says the tool estimates emissions with this formula:
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grams of CO₂ per visit = bytes transferred × 1.8 Wh/GB × 442 gCO₂/kWh
The creator says this works out to roughly 0.36 grams of CO₂ per megabyte. That is a model-based estimate derived from transferred data and stated assumptions. It is not a direct measurement of a specific visit’s electricity use or emissions, and the post does not independently validate the coefficients, PageSpeed measurements, or resulting value.
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That distinction matters when using the number. Treat it as an indicator for comparing or investigating page weight under the tool’s assumptions, not as a precise carbon inventory. Actual energy and emissions depend on factors not established by the post, including the circumstances of the visit and the energy sources involved.
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How the A–F grade is weighted
The creator says the grade blends five dimensions using these weights:
| Dimension | Weight stated by the creator |
|---|---|
| Page weight | 30% |
| Estimated CO₂ | 30% |
| HTTP requests | 15% |
| Load time | 10% |
| Lighthouse score | 15% |
The weights total 100%, but they are the author’s design choices, not a validated benchmark or evidence that one grade predicts a site’s real-world environmental impact. The post explicitly asks whether the ratios are right and whether load time should count more. Use the letter grade as a compact summary of this particular rubric; inspect the underlying metrics before deciding what to change.
What to check before acting on a result
- Look beyond the letter. Identify whether weight, request count, load time, or Lighthouse score is driving the grade.
- Keep the estimate in context. The CO₂ figure is calculated from a stated model; it is not a measurement of the emissions from an individual page view.
- Check the test setup. The post says Tardigrade uses PageSpeed Insights but does not establish the exact conditions or repeatability of each result. Avoid treating a single result as a definitive baseline.
- Prioritize actionable evidence. The post describes overall page weight and request totals, but does not confirm a shipped per-resource breakdown that identifies which images, scripts, or fonts contribute most.
Privacy and implementation claims
Digital Ghost says “Nothing is stored” and says the tool has no accounts, audit analytics, or email capture. Those are the creator’s privacy claims; they have not been independently audited here. Anyone evaluating the tool for sensitive or confidential URLs should consider that limitation rather than treating the statement as a verified privacy assessment.
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The author describes a vanilla HTML, CSS, and JavaScript frontend, a Three.js animated tardigrade hero, and a Vercel serverless function that proxies PageSpeed Insights. The post also mentions scroll reveals using IntersectionObserver, dark or light mode based on system preference, and shareable URLs using a ?url= permalink. These are implementation details reported by the creator, not independently verified facts about the current live version.
What the creator is asking developers to evaluate
The post is an invitation to test the demo and share feedback, not a claim that the scoring model is settled. Digital Ghost asks whether the score’s ratios make sense, whether better or more current carbon models should be supported, and what metrics are missing. The author also specifically asks whether the Three.js hero suits a developer tool and whether the URL form and score card work well on mobile.
Best Value
The post lists several possible future additions: TTFB, CLS, and resource-type breakdowns for images, JavaScript, and fonts; a “greenest sites” leaderboard; side-by-side URL comparisons; downloadable PDF or image reports; and a browser extension. These are roadmap ideas contingent on feedback, not confirmed features.
Who may find it useful
Tardigrade may be useful for developers who want a quick, approachable prompt to inspect a page’s weight and performance alongside a model-based carbon estimate. It is less suited to anyone who needs a verified emissions measurement, a fully documented experimental protocol, or detailed diagnosis by resource type, based on what the creator’s post establishes.
If you try it, useful feedback would distinguish between issues with the measurement inputs, the carbon assumptions, the grade’s weighting, and the interface. That helps the creator assess not just whether the tool feels useful, but which part needs the most work.
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