https://twitter.com
Sustainability
· 7 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
81
GRADE
B
FIX
1
REVIEW
3
PASS
3
INFO
0
Checks
73 PASS 3 REVIEW 1 FIX
DTransfer EfficiencyAction49% efficientFIX
Transfer Efficiency
Action49% efficient
49% efficient
Critical::
Transfer efficiency: 49%
An estimated 1378 KB (51%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 1378 KB of unused JavaScript. This wasted data produces 0.32g of unnecessary CO2 per page view.
Total waste: 1378 KB (51% of page weight)
Unused JS 1378 KB
0.32g unnecessary CO2 per visit
Actual transfer 2689 KB
Theoretical minimum 1310 KB
Potential savings 1378 KB (0.32g CO2)
See Deep Analysis sections above for specific optimizations.
BCO2 Per Page Load0.62g CO2 per viewREVIEW
CO2 Per Page Load
0.62g CO2 per view
0.62g CO2 per view
Info::
0.62g CO2 per page view
This page transfers 2.6 MB, producing an estimated 0.62g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.13g, end-user device 0.48g.
Got: 0.62g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 74.6 kg CO2/year
With 10,000 page views per month, this page would generate approximately 74.6 kg of CO2 annually — equivalent to charging 9325 smartphones.
Info::
Green hosting reduces data center emissions
0.62g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 50% of websites
Sustainable Web Design model v4 · Page size: 2.6 MB
Your site
0.62g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.02g
Network
0.13g
End-user device
0.48g
At 10,000 monthly views: Monthly: 6.2 kg · Annual: 74.6 kg · ≈ 9325 smartphone charges
BCarbon Budget50th percentileREVIEW
Carbon Budget
50th percentile
50th percentile
Warning::
0.62g CO2 — above the median website (0.60g)
Heavier than an estimated 50% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 50th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.62g
50th percentile
Cleaner than 50% of websites
✗ Above the median website
vs Median 4% more
vs Target 24% more
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.
A+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Amazon Web Services, CDN: Fastly
Info::
Amazon Web Services: Verified by the Green Web Foundation
Info::
Fastly: 100% renewable energy for edge network
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 Amazon Web Services✓CDN Fastly✓
Amazon Web Services: Verified by the Green Web Foundation
Fastly: 100% renewable energy for edge network
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight95% cachedPASS
Repeat Visit Weight
95% cached
95% cached
Info::
95% reduction on repeat visits
Returning visitors download only 124 KB (vs 2689 KB first visit). 105 of 107 resources are served from browser cache, saving 0.59g CO2 per repeat visit.
Info::
Repeat visit: 0.03g CO2 (first visit: 0.62g)
First visit
2689 KB
Repeat visit
124 KB
95% reduction on repeat visits
Saving 0.59g CO2 per returning visitor
105 resources served from cache · 2 resources re-downloaded
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.