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codeforces.com screenshot

Report Summary

  • 20

    Performance

    Renders faster than
    37% of other websites

  • 83

    Accessibility

    Visual factors better than
    that of 54% of websites

  • 58

    Best Practices

    More advanced features
    available than in
    20% of websites

  • 85

    SEO

    Google-friendlier than
    55% of websites

codeforces.com

Codeforces

Page Load Speed

2.5 sec in total

First Response

14 ms

Resources Loaded

1.7 sec

Page Rendered

778 ms

codeforces.com screenshot

About Website

Visit codeforces.com now to see the best up-to-date Codeforces content for India and also check out these interesting facts you probably never knew about codeforces.com

Codeforces. Programming competitions and contests, programming community

Visit codeforces.com

Key Findings

We analyzed Codeforces.com page load time and found that the first response time was 14 ms and then it took 2.5 sec to load all DOM resources and completely render a web page. This is a poor result, as 50% of websites can load faster.

Performance Metrics

codeforces.com performance score

20

Measured Metrics

name

value

score

weighting

FCP (First Contentful Paint)

Value4.1 s

21/100

10%

LCP (Largest Contentful Paint)

Value5.6 s

17/100

25%

SI (Speed Index)

Value6.2 s

43/100

10%

TBT (Total Blocking Time)

Value2,590 ms

4/100

30%

CLS (Cumulative Layout Shift)

Value0.225

55/100

15%

TTI (Time to Interactive)

Value18.5 s

3/100

10%

Network Requests Diagram

codeforces.com

14 ms

codeforces.com

406 ms

js

49 ms

jquery-1.8.3.js

87 ms

font-awesome.min.css

100 ms

Our browser made a total of 106 requests to load all elements on the main page. We found that 9% of them (10 requests) were addressed to the original Codeforces.com, 67% (71 requests) were made to Codeforces.org and 5% (5 requests) were made to Mathjax.codeforces.org. The less responsive or slowest element that took the longest time to load (411 ms) relates to the external source Mathjax.codeforces.org.

Page Optimization Overview & Recommendations

Page size can be reduced by 240.5 kB (14%)

Content Size

1.7 MB

After Optimization

1.5 MB

  • HTML
  • Images
  • JavaScript
  • CSS

In fact, the total size of Codeforces.com main page is 1.7 MB. This result falls beyond the top 1M of websites and identifies a large and not optimized web page that may take ages to load. Only a small number of websites need less resources to load. Images take 844.9 kB which makes up the majority of the site volume.

HTML Optimization

-84%

Potential reduce by 157.4 kB

  • Original 188.4 kB
  • After minification 175.4 kB
  • After compression 31.0 kB

HTML content can be minified and compressed by a website’s server. The most efficient way is to compress content using GZIP which reduces data amount travelling through the network between server and browser. HTML code on this page is well minified. It is highly recommended that content of this web page should be compressed using GZIP, as it can save up to 157.4 kB or 84% of the original size.

Image Optimization

-6%

Potential reduce by 46.7 kB

  • Original 844.9 kB
  • After minification 798.1 kB

Image size optimization can help to speed up a website loading time. The chart above shows the difference between the size before and after optimization. Codeforces images are well optimized though.

JavaScript Optimization

-6%

Potential reduce by 32.2 kB

  • Original 564.8 kB
  • After minification 564.8 kB
  • After compression 532.6 kB

It’s better to minify JavaScript in order to improve website performance. The diagram shows the current total size of all JavaScript files against the prospective JavaScript size after its minification and compression. This website has mostly compressed JavaScripts.

CSS Optimization

-4%

Potential reduce by 4.2 kB

  • Original 98.8 kB
  • After minification 98.8 kB
  • After compression 94.6 kB

CSS files minification is very important to reduce a web page rendering time. The faster CSS files can load, the earlier a page can be rendered. Codeforces.com has all CSS files already compressed.

Requests Breakdown

Number of requests can be reduced by 83 (82%)

Requests Now

101

After Optimization

18

  • AJAX
  • Images
  • JavaScript
  • CSS

The browser has sent 101 CSS, Javascripts, AJAX and image requests in order to completely render the main page of Codeforces. We recommend that multiple CSS and JavaScript files should be merged into one by each type, as it can help reduce assets requests from 46 to 1 for JavaScripts and from 25 to 1 for CSS and as a result speed up the page load time.

Network Requests Diagram

codeforces.com

codeforces.com

14 ms

codeforces.com

codeforces.com

406 ms

js

js

49 ms

jquery-1.8.3.js

jquery-1.8.3.js

87 ms

font-awesome.min.css

font-awesome.min.css

100 ms

line-awesome.min.css

line-awesome.min.css

348 ms

css

css

39 ms

css

css

86 ms

prettify.css

prettify.css

115 ms

clear.css

clear.css

114 ms

style.css

style.css

115 ms

ttypography.css

ttypography.css

376 ms

problem-statement.css

problem-statement.css

114 ms

second-level-menu.css

second-level-menu.css

137 ms

roundbox.css

roundbox.css

137 ms

datatable.css

datatable.css

121 ms

table-form.css

table-form.css

138 ms

topic.css

topic.css

141 ms

jquery.jgrowl.css

jquery.jgrowl.css

139 ms

facebox.css

facebox.css

139 ms

jquery.wysiwyg.css

jquery.wysiwyg.css

231 ms

jquery.autocomplete.css

jquery.autocomplete.css

232 ms

codeforces.datepick.css

codeforces.datepick.css

232 ms

colorbox.css

colorbox.css

231 ms

jquery.drafts.css

jquery.drafts.css

238 ms

community.css

community.css

241 ms

MathJax.js

MathJax.js

98 ms

prettify.js

prettify.js

240 ms

moment-with-locales.min.js

moment-with-locales.min.js

242 ms

pushstream.js

pushstream.js

248 ms

jquery.easing.min.js

jquery.easing.min.js

246 ms

jquery.lavalamp.min.js

jquery.lavalamp.min.js

250 ms

jquery.jgrowl.js

jquery.jgrowl.js

253 ms

jquery.swipe.js

jquery.swipe.js

257 ms

jquery.hotkeys.js

jquery.hotkeys.js

257 ms

facebox.js

facebox.js

259 ms

jquery.wysiwyg.js

jquery.wysiwyg.js

268 ms

wysiwyg.colorpicker.js

wysiwyg.colorpicker.js

264 ms

wysiwyg.table.js

wysiwyg.table.js

268 ms

wysiwyg.image.js

wysiwyg.image.js

270 ms

wysiwyg.link.js

wysiwyg.link.js

273 ms

jquery.autocomplete.js

jquery.autocomplete.js

282 ms

codeforces-options.js

codeforces-options.js

26 ms

js

js

64 ms

analytics.js

analytics.js

38 ms

style.css

style.css

192 ms

style.css

style.css

191 ms

TeX-AMS_HTML-full.js

TeX-AMS_HTML-full.js

38 ms

jquery.datepick.js

jquery.datepick.js

177 ms

jquery.ie6blocker.js

jquery.ie6blocker.js

181 ms

jquery.colorbox-min.js

jquery.colorbox-min.js

183 ms

jquery.ba-bbq.js

jquery.ba-bbq.js

184 ms

vedd3670a3b1c4e178fdfb0cc912d969e1713874337387

vedd3670a3b1c4e178fdfb0cc912d969e1713874337387

164 ms

collect

collect

105 ms

jquery.drafts.js

jquery.drafts.js

168 ms

clipboard.min.js

clipboard.min.js

170 ms

autosize.min.js

autosize.min.js

172 ms

sjcl.js

sjcl.js

169 ms

codeforces.js

codeforces.js

177 ms

EventCatcher.js

EventCatcher.js

176 ms

preparedVerdictFormats-en.js

preparedVerdictFormats-en.js

176 ms

confetti.min.js

confetti.min.js

88 ms

jquery.markitup.js

jquery.markitup.js

92 ms

set.js

set.js

92 ms

dc3d601ff391e638c1f2b20ec167083978099bbe.png

dc3d601ff391e638c1f2b20ec167083978099bbe.png

34 ms

codeforces-sponsored-by-ton.png

codeforces-sponsored-by-ton.png

36 ms

gb.png

gb.png

177 ms

ru.png

ru.png

280 ms

comment-12x12.png

comment-12x12.png

279 ms

x-update-12x12.png

x-update-12x12.png

33 ms

hourglass.png

hourglass.png

35 ms

paperclip-16x16.png

paperclip-16x16.png

47 ms

voteup.png

voteup.png

47 ms

votedown.png

votedown.png

50 ms

user_16x16.png

user_16x16.png

52 ms

date_16x16.png

date_16x16.png

57 ms

comments_16x16.png

comments_16x16.png

60 ms

tags.png

tags.png

60 ms

ton-100x100.png

ton-100x100.png

66 ms

itmo_small_en-logo.png

itmo_small_en-logo.png

86 ms

control.png

control.png

83 ms

control-270.png

control-270.png

84 ms

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293b3aed1d72c7105a6fdab084e3fffdb8a7ced7.png

44 ms

a6098a9a86e0c293fc1cb6e4d939fff92d048b97.jpg

a6098a9a86e0c293fc1cb6e4d939fff92d048b97.jpg

55 ms

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49 ms

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46 ms

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60aa49ecdb6a668539163c4d7d797ac6f1bb43b3.jpg

50 ms

search-16x16.png

search-16x16.png

76 ms

dg45_pLmvrkcOkBnKsOzXyGWTBcmg-X6Vj_YIg.ttf

dg45_pLmvrkcOkBnKsOzXyGWTBcmg-X6Vj_YIg.ttf

50 ms

an5sBhtktaE

an5sBhtktaE

106 ms

overlay.png

overlay.png

405 ms

fontdata.js

fontdata.js

12 ms

imageFonts.js

imageFonts.js

411 ms

main.js

main.js

34 ms

www-player.css

www-player.css

8 ms

www-embed-player.js

www-embed-player.js

28 ms

base.js

base.js

54 ms

ad_status.js

ad_status.js

178 ms

8bwowYG5RNtA9FhY8KreTMIyRq72TB8rCtAEZTTrOhQ.js

8bwowYG5RNtA9FhY8KreTMIyRq72TB8rCtAEZTTrOhQ.js

128 ms

embed.js

embed.js

38 ms

KFOmCnqEu92Fr1Mu4mxP.ttf

KFOmCnqEu92Fr1Mu4mxP.ttf

7 ms

KFOlCnqEu92Fr1MmEU9fBBc9.ttf

KFOlCnqEu92Fr1MmEU9fBBc9.ttf

38 ms

imagedata.js

imagedata.js

389 ms

id

id

35 ms

Create

Create

107 ms

GenerateIT

GenerateIT

15 ms

Accessibility Review

codeforces.com accessibility score

83

Accessibility Issues

Contrast

These are opportunities to improve the legibility of your content.

Impact

Issue

High

Background and foreground colors do not have a sufficient contrast ratio.

Navigation

These are opportunities to improve keyboard navigation in your application.

Impact

Issue

High

Heading elements are not in a sequentially-descending order

Names and labels

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Impact

Issue

High

Image elements do not have [alt] attributes

Tables and lists

These are opportunities to improve the experience of reading tabular or list data using assistive technology, like a screen reader.

Impact

Issue

High

Lists do not contain only <li> elements and script supporting elements (<script> and <template>).

Best Practices

codeforces.com best practices score

58

Areas of Improvement

Trust and Safety

Impact

Issue

High

Does not use HTTPS

High

Includes front-end JavaScript libraries with known security vulnerabilities

Low

Ensure CSP is effective against XSS attacks

User Experience

Impact

Issue

High

Serves images with low resolution

General

Impact

Issue

Low

Detected JavaScript libraries

High

Browser errors were logged to the console

High

Page has valid source maps

SEO Factors

codeforces.com SEO score

85

Search Engine Optimization Advices

Content Best Practices

Format your HTML in a way that enables crawlers to better understand your app’s content.

Impact

Issue

High

Links do not have descriptive text

High

Image elements do not have [alt] attributes

Mobile Friendly

Make sure your pages are mobile friendly so users don’t have to pinch or zoom in order to read the content pages. [Learn more](https://developers.google.com/search/mobile-sites/).

Impact

Issue

High

Document uses legible font sizes

Language and Encoding

  • Language Detected

    EN

  • Language Claimed

    EN

  • Encoding

    UTF-8

Language claimed in HTML meta tag should match the language actually used on the web page. Otherwise Codeforces.com can be misinterpreted by Google and other search engines. Our service has detected that English is used on the page, and it matches the claimed language. Our system also found out that Codeforces.com main page’s claimed encoding is utf-8. Use of this encoding format is the best practice as the main page visitors from all over the world won’t have any issues with symbol transcription.

Social Sharing Optimization

codeforces.com

Open Graph description is not detected on the main page of Codeforces. Lack of Open Graph description can be counter-productive for their social media presence, as such a description allows converting a website homepage (or other pages) into good-looking, rich and well-structured posts, when it is being shared on Facebook and other social media. For example, adding the following code snippet into HTML <head> tag will help to represent this web page correctly in social networks: