developer.mozilla.org — updown.website

Response Time & Availability (24h)

SSL / TLS Certificate

74

days left

Valid

Mar 27, 2026 Jun 25, 2026

Issued → Expires

Subject	`commonName=developer.mozilla.org`
Issuer	countryName=US, organizationName=Let's Encrypt, commonName=R13
Valid From	2026-03-27 15:31
Expires	2026-06-25 15:31
Serial Number	`053551E7FDB1B25F6B73A6B31A4D118145D2`
SHA-256 Fingerprint	`00:b5:87:f7:af:4a:a9:27:76:a8:36:3f:9c:1d:67:bd:f9:cf:8e:3e:67:28:15:ae:b1:c3:2d:5f:e3:51:9e:4a`
Subject Alt Names	*.mdnplay.dev developer.mozilla.org mdnplay.dev
Last Checked	2026-04-11 21:11:18

Latest HTTP Response Details

Final URL	`https://developer.mozilla.org/en-US/`
Status Code	200
Response Time	288 ms
Content Size	110 KB (109.9 KB)
Content Type	`text/html`
Server	Google Frontend

TLS Version	TLSv1.3
TLS Cipher	`TLS_AES_128_GCM_SHA256`
Redirects	1
`https://developer.mozilla.org/`
Checked	2026-04-11 21:11:18

Security Headers 5/6

Header	Status	Value
`Strict-Transport-Security`	Present	max-age=63072000
`Content-Security-Policy`	Present	default-src 'self'; script-src 'report-sample' 'self' 'wasm-unsafe-eval' assets.codepen.io production-assets.codepen.io https://js.stripe.com transcend-cdn.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; script-src-elem 'report-sample' 'self' 'wasm-unsafe-eval' assets.codepen.io production-assets.codepen.io https://js.stripe.com transcend-cdn.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; style-src 'report-sample' 'self' 'unsafe-inline' transcend-cdn.com; object-src 'none'; base-uri 'self'; connect-src 'self' developer.allizom.org bcd.developer.allizom.org bcd.developer.mozilla.org updates.developer.allizom.org updates.developer.mozilla.org https://incoming.telemetry.mozilla.org https://observatory-api.mdn.allizom.net https://observatory-api.mdn.mozilla.net telemetry.transcend.io telemetry.us.transcend.io transcend-cdn.com https://api.github.com/search/issues https://api.stripe.com; font-src 'self'; frame-src 'self' mdn.github.io .mdnplay.dev .mdnyalp.dev .play.test.mdn.allizom.net https://v2.scrimba.com https://scrimba.com jsfiddle.net www.youtube-nocookie.com codepen.io survey.alchemer.com https://js.stripe.com; img-src 'self' data: .githubusercontent.com *.gravatar.com mozillausercontent.com firefoxusercontent.com profile.stage.mozaws.net profile.accounts.firefox.com developer.mozilla.org mdn.dev wikipedia.org upload.wikimedia.org https://mdn.github.io/shared-assets/ https://mdn.dev/; manifest-src 'self'; media-src 'self' archive.org videos.cdn.mozilla.net https://mdn.github.io/shared-assets/; child-src 'self'; worker-src 'self';
`X-Frame-Options`	Present	DENY
`X-Content-Type-Options`	Present	nosniff
`Referrer-Policy`	Present	strict-origin-when-cross-origin
`Permissions-Policy`	Missing	—

DNS Intelligence (24h)

Avg Resolution

5.7 ms

Min / Max

4.1 / 7.7 ms

Record Types

3

Lookups (24h)

6

DNS Records

A

151.101.1.91 151.101.193.91 151.101.129.91 151.101.65.91

24s 7.7ms

AAAA

2a04:4e42::347 2a04:4e42:200::347 2a04:4e42:400::347 2a04:4e42:600::347

17s 6.0ms

CNAME

mozilla.map.fastly.net

23s 5.5ms

Email Security Posture

MX Records

SPF

DMARC

BIMI

MTA-STS

Weak

Overall

DNS Propagation Inconsistent

Resolver	IPs Returned	Response Time
Quad9	`151.101.1.91` `151.101.129.91` `151.101.193.91` `151.101.65.91`	12.14ms
Google	`151.101.1.91` `151.101.129.91` `151.101.193.91` `151.101.65.91`	15.66ms
AdGuard	`199.232.89.91`	51.58ms
OpenDNS	`151.101.1.91` `151.101.129.91` `151.101.193.91` `151.101.65.91`	134.39ms
Cloudflare	`151.101.1.91` `151.101.129.91` `151.101.193.91` `151.101.65.91`	4.69ms

WHOIS / Domain Registration

Registrar

MarkMonitor Inc.

Created

1998-01-24

Updated

2024-12-27

Expires

2027-01-23

Name Servers (WHOIS)

ns1-240.akam.net ns4-64.akam.net ns5-65.akam.net ns7-66.akam.net

Domain Status

clientDeleteProhibited clientTransferProhibited clientUpdateProhibited

DNSSEC

Unsigned

WHOIS Last Checked

2026-04-11 21:11

Resolution Time (A/AAAA recent)

20:07 21:11

Time	Type	Values	TTL	Resolution	Nameserver
21:11:16	CNAME	`mozilla.map.fastly.net`	23s	5.5 ms	`10.89.0.1`
21:11:16	AAAA	`2a04:4e42::347` `2a04:4e42:200::347` `2a04:4e42:400::347` `2a04:4e42:600::347`	17s	6.0 ms	`10.89.0.1`
21:11:16	A	`151.101.1.91` `151.101.193.91` `151.101.129.91` `151.101.65.91`	24s	7.7 ms	`10.89.0.1`
20:07:57	CNAME	`mozilla.map.fastly.net`	57s	1.0 ms	`10.89.0.1`
20:07:57	AAAA	`2a04:4e42:200::347` `2a04:4e42::347` `2a04:4e42:400::347` `2a04:4e42:600::347`	26s	4.9 ms	`10.89.0.1`
20:07:57	A	`151.101.193.91` `151.101.129.91` `151.101.65.91` `151.101.1.91`	58s	4.1 ms	`10.89.0.1`

Open Ports 10

Open Ports

10

IPs Scanned

10

Port	Protocol	Service	IP Address	Status	Latency	Banner
`80`	TCP	http	`151.101.193.91`	Open	1.9 ms	—
`80`	TCP	http	`2a04:4e42:400::347`	Open	1.9 ms	—
`80`	TCP	http	`151.101.129.91`	Open	1.7 ms	—
`80`	TCP	http	`2a04:4e42:200::347`	Open	5.5 ms	—
`443`	TCP	https	`151.101.129.91`	Open	1.4 ms	—
`443`	TCP	https	`151.101.193.91`	Open	5.6 ms	—
`443`	TCP	https	`2a04:4e42:200::347`	Open	4.9 ms	—
`443`	TCP	https	`2a04:4e42:400::347`	Open	1.8 ms	—
`8443`	TCP	https-alt	`2a04:4e42:400::347`	Open	2.8 ms	—
`8443`	TCP	https-alt	`2a04:4e42:200::347`	Open	3.7 ms	—

Lighthouse Report

9 minutes ago

Mobile screenshot of developer.mozilla.org

Mobile viewport

52

Performance

96

Accessibility

96

Best Practices

100

SEO

● 90–100 Good ● 50–89 Needs Work ● 0–49 Poor

Core Web Vitals: Failed

LCP

4644 ms

Poor

TBT

901 ms

Poor

CLS

0.049

Good

FCP

3549 ms

Poor

SI

5032 ms

Needs Work

TTFB

5 ms

Good

Score	Audit	Category
0	Max Potential First Input Delay 840 ms	performance
0	Avoid multiple page redirects Est savings of 770 ms	performance
0	Displays images with incorrect aspect ratio	best-practices
0	Minimize main-thread work 5.9 s	performance
0	Reduce JavaScript execution time 2.4 s	performance
0	Preconnect to required origins Est savings of 320 ms	performance
0	Reduce the impact of third-party code Third-party code blocked the main thread for 420 ms	performance
0	Largest Contentful Paint element 4,640 ms	performance
0	Touch targets do not have sufficient size or spacing.	accessibility
0	Eliminate render-blocking resources Est savings of 1,120 ms	performance
0	Reduce unused JavaScript Est savings of 74 KiB	performance
0	Enable text compression Est savings of 2 KiB	performance
0	Avoid an excessive DOM size 824 elements	performance
0	Use efficient cache lifetimes Est savings of 175 KiB	performance
0	Document request latency Est savings of 220 ms	performance
0	Network dependency tree	performance
0	Render blocking requests Est savings of 1,120 ms	performance
31	Total Blocking Time 900 ms	performance
33	First Contentful Paint 3.5 s	performance
34	Largest Contentful Paint 4.6 s	performance
50	Serve static assets with an efficient cache policy 6 resources found	performance
50	Defer offscreen images Est savings of 3 KiB	performance
50	Serve images in next-gen formats Est savings of 13 KiB	performance
50	Properly size images Est savings of 60 KiB	performance
50	Improve image delivery Est savings of 74 KiB	performance
63	Speed Index 5.0 s	performance
76	Time to Interactive 5.0 s	performance

Desktop screenshot of developer.mozilla.org

Desktop viewport

66

Performance

96

Accessibility

100

Best Practices

100

SEO

● 90–100 Good ● 50–89 Needs Work ● 0–49 Poor

Core Web Vitals: Passed

LCP

1534 ms

Good

TBT

707 ms

Poor

CLS

0.049

Good

FCP

825 ms

Good

SI

1654 ms

Good

TTFB

6 ms

Good

Score	Audit	Category
0	Avoid multiple page redirects Est savings of 210 ms	performance
0	Minimize main-thread work 3.9 s	performance
0	Reduce JavaScript execution time 1.6 s	performance
0	Preconnect to required origins Est savings of 100 ms	performance
0	Reduce the impact of third-party code Third-party code blocked the main thread for 260 ms	performance
0	Largest Contentful Paint element 1,530 ms	performance
0	Touch targets do not have sufficient size or spacing.	accessibility
0	Eliminate render-blocking resources Est savings of 280 ms	performance
0	Reduce unused JavaScript Est savings of 74 KiB	performance
0	Enable text compression Est savings of 2 KiB	performance
0	Use efficient cache lifetimes Est savings of 175 KiB	performance
0	Document request latency Est savings of 220 ms	performance
0	LCP request discovery	performance
0	Network dependency tree	performance
0	Render blocking requests Est savings of 320 ms	performance
14	Total Blocking Time 710 ms	performance
23	Max Potential First Input Delay 360 ms	performance
50	Serve static assets with an efficient cache policy 6 resources found	performance
50	Serve images in next-gen formats Est savings of 13 KiB	performance
50	Properly size images Est savings of 63 KiB	performance
50	Avoid an excessive DOM size 824 elements	performance
50	Improve image delivery Est savings of 64 KiB	performance
77	Speed Index 1.7 s	performance
79	Largest Contentful Paint 1.5 s	performance

Technology Stack 9 detected

HTTP/2

HTTP/3 (QUIC)

9

Technologies

CDN 1

Fastly

90%

X-Served-By header

Cache 1

Varnish v1.1

90%

Via header

SEO 1

Schema.org Markup

70%

Schema.org structured data

Security 5

CSP v8

90%

Content-Security-Policy present

HSTS

90%

HSTS header present

Referrer-Policy

90%

Referrer-Policy present

X-Content-Type-Options

90%

nosniff header

X-Frame-Options

90%

Security header present

Social 1

Twitter Cards

70%

Twitter Card meta

Crawl Configuration

robots.txt Sitemap · 10 URLs

robots.txt 3 disallow · 0 allow · 1 agent

User-Agent	Directive	Path / Value
`*`	Sitemap	https://developer.mozilla.org/sitemap.xml
`*`	Disallow	`/api/`
`*`	Disallow	`/*/files/`
`*`	Disallow	`/media`

User-agent: *
Sitemap: https://developer.mozilla.org/sitemap.xml

Disallow: /api/
Disallow: /*/files/
Disallow: /media

Sitemap

Discovered URL

https://developer.mozilla.org/sitemap.xml

10

URLs

Sitemap Accessible

Standard

Active IP Addresses

IP Address	Version	Reverse DNS	CIDR	Country	City	ASN	First Seen	Last DNS	Hits	Uptime %	Avg Latency
`2a04:4e42::347`	IPv6	—	`2a04:4e42::/48`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	3.7 ms
`2a04:4e42:400::347`	IPv6	—	`2a04:4e42:400::/48`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	3.0 ms
`2a04:4e42:600::347`	IPv6	—	`2a04:4e42:600::/48`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	2.6 ms
`2a04:4e42:200::347`	IPv6	—	`2a04:4e42:200::/48`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	11.1 ms
`151.101.129.91`	IPv4	—	`151.101.129.0/24`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	2.3 ms
`151.101.65.91`	IPv4	—	`151.101.65.0/24`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	2.2 ms
`151.101.1.91`	IPv4	—	`151.101.1.0/24`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	2.5 ms
`151.101.193.91`	IPv4	—	`151.101.193.0/24`	US	—	AS54113 Fastly, Inc.	2026-04-11 20:07	2026-04-11 21:11	2	100.0%	2.8 ms

Discovered Sub-domains 6

Wordlist Brute-force 2 Certificate Transparency 4

1. api.developer.mozilla.org

2. wiki.developer.mozilla.org

bcd.developer.mozilla.org 1 hour, 47 minutes ago

contribute.developer.mozilla.org 1 hour, 47 minutes ago

insights.developer.mozilla.org 1 hour, 47 minutes ago

updates.developer.mozilla.org 1 hour, 47 minutes ago

Recent HTTP Checks (24 h)

Total Checks

2

Success Rate

100%

Avg Response

296 ms

Min / Max

288 / 305 ms

Recent Checks

20:07 21:11

Time	Status	Code	Response	Agent	Error
21:11:18	UP	200	288 ms	prod-local	—
20:07:58	UP	200	305 ms	prod-local	—

Incident History

No incidents recorded — all clear!