https://www.npmjs.com
Sustainability
· 7 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
86
GRADE
B
FIX
0
REVIEW
2
PASS
5
INFO
0
Checks
75 PASS 2 REVIEW
CTransfer EfficiencyAction75% efficientREVIEW
Transfer Efficiency
Action75% efficient
75% efficient
Warning::
Transfer efficiency: 75%
An estimated 287 KB (25%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 287 KB of unused JavaScript. This wasted data produces 0.07g of unnecessary CO2 per page view.
Total waste: 287 KB (25% of page weight)
Unused JS 287 KB
0.07g unnecessary CO2 per visit
Actual transfer 1149 KB
Theoretical minimum 861 KB
Potential savings 287 KB (0.07g CO2)
See Deep Analysis sections above for specific optimizations.
BWeb Font Weight VariantsNo detectable Google Fonts weightsREVIEW
Web Font Weight Variants
No detectable Google Fonts weights
No detectable Google Fonts weights
Info::
No detectable Google Fonts weights
The analyzer detects font weights via Google Fonts URL parameters (~70% of font-using sites). Self-hosted fonts and non-Google CDN fonts aren't visible to URL-based detection. If you self-host fonts, manually audit how many @font-face weights you ship -- 2-3 weights per family is typically enough; 5+ is usually unused payload.
ACO2 Per Page Load0.27g CO2 per viewPASS
CO2 Per Page Load
0.27g CO2 per view
0.27g CO2 per view
Info::
0.27g CO2 per page view
This page transfers 1.1 MB, producing an estimated 0.27g 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: 0.27g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 31.9 kg CO2/year
With 10,000 page views per month, this page would generate approximately 31.9 kg of CO2 annually — equivalent to charging 3985 smartphones.
Info::
Green hosting reduces data center emissions
0.27g
Carbon Footprint per page view
✓ Below sustainability target (0.50g)
Cleaner than 84% of websites
Sustainable Web Design model v4 · Page size: 1.1 MB
Your site
0.27g
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: 2.7 kg · Annual: 31.9 kg · ≈ 3985 smartphone charges
A+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Cloudflare, CDN: Cloudflare
Info::
Cloudflare: Verified by the Green Web Foundation
Info::
Cloudflare: 100% renewable energy for global network since 2019
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 Cloudflare✓CDN Cloudflare✓
Cloudflare: Verified by the Green Web Foundation
Cloudflare: 100% renewable energy for global network since 2019
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight99% cachedPASS
Repeat Visit Weight
99% cached
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 10 KB (vs 1149 KB first visit). 19 of 20 resources are served from browser cache, saving 0.26g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.27g)
First visit
1149 KB
Repeat visit
10 KB
99% reduction on repeat visits
Saving 0.26g CO2 per returning visitor
19 resources served from cache · 1 resources re-downloaded
ACarbon Budget16th percentilePASS
Carbon Budget
16th percentile
16th percentile
Info::
0.27g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 84% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 16th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.27g
16th percentile
Cleaner than 84% of websites
✓ Below the Web Sustainability Guidelines target
vs Median 56% cleaner ✓
vs Target 47% cleaner ✓
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.