https://reactjs.org
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
87
GRADE
B
FIX
0
REVIEW
2
PASS
4
INFO
0
Checks
64 PASS 2 REVIEW
BTransfer Efficiency81% efficientREVIEW
Transfer Efficiency
81% efficient
81% efficient
Info::
Transfer efficiency: 81%
An estimated 209 KB (19%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 209 KB of unused JavaScript. This wasted data produces 0.05g of unnecessary CO2 per page view.
Total waste: 209 KB (19% of page weight)
Unused JS 209 KB
0.05g unnecessary CO2 per visit
Actual transfer 1105 KB
Theoretical minimum 895 KB
Potential savings 209 KB (0.05g CO2)
See Deep Analysis sections above for specific optimizations.
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
ActionWhether the site is served from green-energy infrastructure
Green Hosting
No green hosting detected
ACO2 Per Page Load0.26g CO2 per viewPASS
CO2 Per Page Load
0.26g CO2 per view
0.26g CO2 per view
Info::
0.26g CO2 per page view
This page transfers 1.1 MB, producing an estimated 0.26g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.05g, end-user device 0.20g.
Got: 0.26g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 30.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 30.7 kg of CO2 annually — equivalent to charging 3832 smartphones.
Info::
Green hosting reduces data center emissions
0.26g
Carbon Footprint per page view
✓ Below sustainability target (0.50g)
Cleaner than 85% of websites
Sustainable Web Design model v4 · Page size: 1.1 MB
Your site
0.26g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.01g
Network
0.05g
End-user device
0.20g
At 10,000 monthly views: Monthly: 2.6 kg · Annual: 30.7 kg · ≈ 3832 smartphone charges
AGreen HostingGreen (cdn)PASS
Green Hosting
Green (cdn)
Green (cdn)
Info::
Vercel CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Vercel: Hosted on AWS/Google Cloud with renewable energy commitments
Info::
Green hosting status based on known provider commitments
Green hosting detection uses a curated database of provider renewable energy commitments. This is not a real-time verification. For authoritative checks, visit thegreenwebfoundation.org.
Green Hosting✓ Green Hosted
Hosting Next.js✗CDN Vercel✓
Vercel: Hosted on AWS/Google Cloud with renewable energy commitments
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight96% cachedPASS
Repeat Visit Weight
96% cached
96% cached
Info::
96% reduction on repeat visits
Returning visitors download only 42 KB (vs 1105 KB first visit). 68 of 69 resources are served from browser cache, saving 0.25g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.26g)
First visit
1105 KB
Repeat visit
42 KB
96% reduction on repeat visits
Saving 0.25g CO2 per returning visitor
68 resources served from cache · 1 resources re-downloaded
ACarbon Budget15th percentilePASS
Carbon Budget
15th percentile
15th percentile
Info::
0.26g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 85% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 15th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.26g
15th percentile
Cleaner than 85% of websites
✓ Below the Web Sustainability Guidelines target
vs Median 57% cleaner ✓
vs Target 49% cleaner ✓
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.