HTTP Headers Analysis for https://esm.run

Detected Technologies from Headers

See all in URL Inspect 2

Cloudflare NEL Monitoring

Cloudflare CDN

HTTP Security Headers

Status

Strict-Transport-Security

Excellent

max-age=31536000; includeSubDomains; preload

Content-Security-Policy

Missing

Not configured Analyze

Content-Security-Policy-Report-Only

Missing

Not configured Analyze

X-Frame-Options

Missing

Not configured

X-Content-Type-Options

Missing

Not configured

Referrer-Policy

Missing

Not configured

Permissions-Policy

Missing

Not configured

Recommendations

• Add Content-Security-Policy header to prevent XSS attacks
• Add X-Frame-Options: DENY or SAMEORIGIN to prevent clickjacking
• Add X-Content-Type-Options: nosniff
• Add Referrer-Policy header (recommended: strict-origin-when-cross-origin)
• Consider adding Permissions-Policy to control browser features

Performance Headers

Connection

Performance

close

Transfer-Encoding

Performance

chunked

Vary

Performance

Accept-Encoding

connection: close
transfer-encoding: chunked
vary: Accept-Encoding

Caching Headers

Age

Caching

180

Cache-Control

Caching

public, max-age=300, must-revalidate, stale-while-revalidate=600, stale-if-error=86400

age: 180
cache-control: public, max-age=300, must-revalidate, stale-while-revalidate=600, stale-if-error=86400

Content Headers

Content-Type

Content

text/html; charset=utf-8

content-type: text/html; charset=utf-8

Server Headers

Server

cloudflare

server: cloudflare

CORS Headers

No CORS headers found

Cookies Headers

No cookies headers found

Other Headers

Alt-Svc

Other

h3=":443"; ma=86400

Cf-Cache-Status

Other

HIT

Cf-Ray

Other

a2b0b30d3bed0580-IAD

Date

Other

Fri, 14 Aug 2026 14:37:46 GMT

Link

Other

URL https://www.jsdelivr.com/esm

rel=canonical

Nel

Other

Report-To Group cf-nel max-age: 1w

success: 0.0%

Report-To

Other

Group cf-nel max-age: 1w

Endpoint 1 https://a.nel.cloudflare.com/report/v4?s=k%2BtNu6Z3BnD34YRivOczqeMIIeIXLQPhZQJBnit%2BTIb8GgzEdKmlYFq1fB1gXGrSbVKcswHutCB%2BJyBUG3XEct9nUOBPYcpEeCNv3X5%2BQm5hyFiOGL2wmbaGgX8XgT%2FvygEg

X-Response-Time

Other

5ms

alt-svc: h3=":443"; ma=86400
cf-cache-status: HIT
cf-ray: a2b0b30d3bed0580-IAD
date: Fri, 14 Aug 2026 14:37:46 GMT
link: <https://www.jsdelivr.com/esm>; rel="canonical"
nel: {"report_to":"cf-nel","success_fraction":0.0,"max_age":604800}
report-to: {"group":"cf-nel","max_age":604800,"endpoints":[{"url":"https://a.nel.cloudflare.com/report/v4?s=k%2BtNu6Z3BnD34YRivOczqeMIIeIXLQPhZQJBnit%2BTIb8GgzEdKmlYFq1fB1gXGrSbVKcswHutCB%2BJyBUG3XEct9nUOBPYcpEeCNv3X5%2BQm5hyFiOGL2wmbaGgX8XgT%2FvygEg"}]}
x-response-time: 5ms

Recommendations

Enable compression (gzip/brotli) to improve performance