0.305 g
cleaner than an estimated 56.7% of pages on the web
- A+
- A
- B
- C
- D
- E
- F
A+ is 0.04 g or less per view, F is more than 0.359 g CO₂e.
The numbers
- 0.396 g CO₂e
- 0.032 g CO₂e
- verified green
- 488 ms
- 0.001
- 169 ms
At 10,000 views a month this page emits about 36.6 kg CO₂e a year, roughly 150 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 8%, and world-average grid intensity. How we calculate this
What to fix
apply everything → ~0.186 g/visit, rating C
Convert and compress imagessave ~0.036 g/visit (388 kB)High impact · quick fix
68 images (253 kB) ship in legacy formats (JPEG/PNG/GIF); 1 image exceeds 300 kB apiece.
Serve AVIF (or WebP) with responsive srcset sizes, and re-compress oversized files. AVIF typically halves JPEG weight at the same visual quality.
- main-img.webp698 kB
- 81043844 kB
- 23054129 kB
- 5546220 kB
- 640220518 kB
Reduce JavaScript payloadsave ~0.025 g/visit (266 kB)High impact · moderate effort
43 scripts total 1.06 MB on the wire (3.66 MB decoded). Bundles this size usually carry a lot of unused code.
Split bundles per route, tree-shake dependencies, and audit with a bundle analyzer or coverage profile. A 25% cut is a conservative target for bundles this size.
- js160 kB
- 0zbnd2riu8w16.js141 kB
- 0xm6fhdjw-nmw.js129 kB
- 02g57688aesqw.js59 kB
- 0agz51~94r2c2.js51 kB
Optimize web fontssave ~0.021 g/visit (225 kB)Medium impact · quick fix
8 font files total 643 kB.
Subset fonts to used glyphs, prefer one variable font over multiple weights, serve WOFF2 only, and consider system fonts for UI text.
- IBMPlexSerif_Var_Italic-s.p.012.243xfxwiq.woff2176 kB
- IBMPlexSerif_Var-s.p.0514woj1b7y35.woff2165 kB
- Lilex_Regular-s.p.15fuilmy_nwr..woff265 kB
- IBMPlexSans_Regular-s.p.0r~h.uth-bdby.woff264 kB
- iAWriterQuattroS_Bold-s.p.16smx126ex5d3.woff245 kB
Audit third-party servicessave ~0.019 g/visit (207 kB)Medium impact · moderate effort
5 third-party domains account for 414 kB (13% of the page).
Remove services that no longer earn their place; load the rest on interaction (facades for embeds, delayed consent-gated tags). Each third party is also a privacy and performance dependency.
- avatars.githubusercontent.com241 kB
- www.googletagmanager.com160 kB
- github.com11 kB
- zed-us-east-1-zed-production.c15t.dev1.5 kB
- pagead2.googlesyndication.com0 B
Upgrade compression beyond gzipsave ~0.018 g/visit (191 kB)Advisory · quick fix
1.27 MB of text ships gzip-compressed; Brotli or Zstandard would cut roughly another 15-20%, and browsers without them fall back to gzip automatically.
Serve precompressed Brotli for static text assets (highest level, compressed at build time) and enable Brotli or zstd for dynamic responses; keep gzip only as the fallback.
- zed.dev227 kB
- 0zbnd2riu8w16.js141 kB
- 0xm6fhdjw-nmw.js129 kB
- 02g57688aesqw.js59 kB
- 0agz51~94r2c2.js51 kB
Remove references to broken resourcessave ~<0.001 g/visit (323 B)Advisory · quick fix
1 request answered 4xx/5xx on load: transfer and connections spent on nothing, on every single visit.
Delete or fix the references (stale asset URLs, dead third-party tags). Each one is a request the page provably does not need.
- sessionHTTP 401 · 323 B
Set a page-weight budgetAdvisory · moderate effort
At 3.27 MB per view this page rates E. The findings above list where the weight is.
Agree a transfer budget (e.g. under 975 kB reaches a B), enforce it in CI, and re-scan after each change to hold the line.
Simplify the document structureAdvisory · larger effort
The page renders 6405 DOM elements, above the 1,500 guideline. Large trees cost memory and CPU on every visitor's device.
Flatten wrapper markup, render long lists virtually or paginate, and prefer semantic elements over nested divs.
Where the bytes are
- Images1.20 MB · 87 req
- JavaScript1.06 MB · 43 req
- Fonts643 kB · 8 req
- HTML227 kB · 1 req
- Data (fetch)95 kB · 38 req
- CSS46 kB · 2 req
- Other0 B · 2 req
Ten heaviest requests
| Resource | Type | Wire size | Cache-Control |
|---|---|---|---|
| images.zed.dev/blog/introducing-delta/main-img.webp | image | 698 kB | n/a |
| zed.dev/ | document | 227 kB | s-maxage=31536000, stale-while-revalidate=2592000 |
| zed.dev/_next/static/media/IBMPlexSerif_Var_Italic-s.p.012.243xfxwiq.woff2 | font | 176 kB | public,max-age=31536000,immutable |
| zed.dev/_next/static/media/IBMPlexSerif_Var-s.p.0514woj1b7y35.woff2 | font | 165 kB | public,max-age=31536000,immutable |
| www.googletagmanager.com/gtag/js?id=AW-17960676309 | script | 160 kB | private, max-age=900 |
| zed.dev/_next/static/chunks/0zbnd2riu8w16.js | script | 141 kB | public,max-age=31536000,immutable |
| zed.dev/_next/static/chunks/0xm6fhdjw-nmw.js | script | 129 kB | public,max-age=31536000,immutable |
| zed.dev/_next/static/media/Lilex_Regular-s.p.15fuilmy_nwr..woff2 | font | 65 kB | public,max-age=31536000,immutable |
| zed.dev/_next/static/media/IBMPlexSans_Regular-s.p.0r~h.uth-bdby.woff2 | font | 64 kB | public,max-age=31536000,immutable |
| zed.dev/_next/static/chunks/02g57688aesqw.js | script | 59 kB | public,max-age=31536000,immutable |
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<a href="https://carbonless.cc/report/zed.dev"><img src="https://carbonless.cc/api/badge?url=https%3A%2F%2Fzed.dev" alt="Carbon rating for this page" width="150" height="30" loading="lazy" /></a>The badge is a lightweight SVG (under 1 kB) served with long-lived caching, so a new scan can take up to a day to show through.