--- title: "Best JavaScript CDN in 2026: jsDelivr vs unpkg vs cdnjs vs esm.sh" description: "Which public JavaScript CDN is fastest and most reliable in 2026: jsDelivr, unpkg, cdnjs and esm.sh compared on speed, ESM support and caching." image: https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-18-2026-07-00-33-2719-AM.jpeg --- [![BlazingCDN](https://blog.blazingcdn.com/hubfs/Logo/blog-logo-w.png)](https://blog.blazingcdn.com?hsLang=en-us) [๐Ÿ“˜Learn โ–พ](https://blog.blazingcdn.com/cdn-learn?hsLang=en-us) [CDN Fundamentals](https://blog.blazingcdn.com/cdn-fundamentals?hsLang=en-us) [By Content Type](https://blog.blazingcdn.com/by-content-type?hsLang=en-us) [Advanced Concepts](https://blog.blazingcdn.com/advanced-concepts?hsLang=en-us) [Glossary](https://blog.blazingcdn.com/glossary?hsLang=en-us) [โšก Web Performance](https://blog.blazingcdn.com/web-performance?hsLang=en-us) [๐ŸŽฌVideo & Streaming โ–พ](https://blog.blazingcdn.com/video-streaming-cdn?hsLang=en-us) [๐Ÿ”ด Live Streaming](https://blog.blazingcdn.com/live-streaming?hsLang=en-us) [๐Ÿ“บ VOD & OTT](https://blog.blazingcdn.com/vod-ott?hsLang=en-us) [๐Ÿ’ฐ Bandwidth & Costs](https://blog.blazingcdn.com/bandwidth-costs?hsLang=en-us) [๐Ÿญ Other Industries โ–พ](https://blog.blazingcdn.com/cdn-industry-insights?hsLang=en-us) [๐Ÿ“บ Media & Broadcasting](https://blog.blazingcdn.com/media-broadcasting?hsLang=en-us) [๐Ÿ’พ Software & SaaS](https://blog.blazingcdn.com/software-saas?hsLang=en-us) [๐Ÿ—๏ธ DevOps & Cloud Infra](https://blog.blazingcdn.com/devops-cloud-infra?hsLang=en-us) [๐Ÿ“š AdTech & Advertising](https://blog.blazingcdn.com/adtech-advertising?hsLang=en-us) [๐ŸŽฎ Gaming & Esports](https://blog.blazingcdn.com/gaming-esports?hsLang=en-us) [๐Ÿ“ฑ Mobile Apps & Developers](https://blog.blazingcdn.com/mobile-apps-developers?hsLang=en-us) [๐Ÿค– AI & Machine Learning](https://blog.blazingcdn.com/ai-machine-learning?hsLang=en-us) [๐Ÿ›๏ธ Enterprise & Corporate](https://blog.blazingcdn.com/enterprise-corporate?hsLang=en-us) [๐Ÿ“š E-Learning & EdTech](https://blog.blazingcdn.com/e-learning-edtech?hsLang=en-us) [๐ŸŸ๏ธ Sports & Live Events](https://blog.blazingcdn.com/sports-live-events?hsLang=en-us) [๐Ÿ’ฐ Pricing & Costs โ–พ](https://blog.blazingcdn.com/cdn-pricing-and-cdn-costs?hsLang=en-us) [Provider Pricing](https://blog.blazingcdn.com/provider-pricing?hsLang=en-us) [Cost Optimization](https://blog.blazingcdn.com/cost-optimization?hsLang=en-us) [Decision Support](https://blog.blazingcdn.com/decision-support?hsLang=en-us) [โšกCompare โ–พ](https://blog.blazingcdn.com/cdn-comparison?hsLang=en-us) [Provider Comparisons](https://blog.blazingcdn.com/provider-comparisons?hsLang=en-us) [Strategy Comparisons](https://blog.blazingcdn.com/strategy-comparisons?hsLang=en-us) [Ratings & Benchmarks](https://blog.blazingcdn.com/cdn-ratings-and-benchmarks?hsLang=en-us) [๐Ÿ“Š Benchmarks](https://blog.blazingcdn.com/cdn-ratings-and-benchmarks?hsLang=en-us) [๐Ÿ”’ Security โ–พ](https://blog.blazingcdn.com/cdn-security?hsLang=en-us) [Attack Protection](https://blog.blazingcdn.com/attack-protection?hsLang=en-us) [Encryption & Access](https://blog.blazingcdn.com/encryption-access?hsLang=en-us) [Video & DRM Security](https://blog.blazingcdn.com/video-drm-security?hsLang=en-us) [๐Ÿ“ Case Studies](https://blog.blazingcdn.com/case-studies?hsLang=en-us) [๐Ÿ”Œ Integrations](https://blog.blazingcdn.com/integrations?hsLang=en-us) [๐Ÿ› ๏ธ Tools](https://blog.blazingcdn.com/cdn-tools?hsLang=en-us) [Get Started](https://blazingcdn.com/sign-up-contact-form/) [Compare](https://blog.blazingcdn.com/en-us/tag/compare) [Compare - Provider Comparisons](https://blog.blazingcdn.com/en-us/tag/compare-provider-comparisons) # Best JavaScript CDN in 2026: jsDelivr vs unpkg vs cdnjs vs esm.sh BlazingCDN Sep 18, 2026, 9:02:39โ€ฏAM ![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-18-2026-07-00-33-2719-AM.jpeg) # Best JavaScript CDN in 2026: jsDelivr vs unpkg vs cdnjs vs esm.sh Skypack stopped being a serious answer to "what's the best JavaScript CDN" sometime in 2024, and by 2026 its build service is effectively frozen โ€” packages published after its last reliable indexing window either fail to resolve or return stale transforms. That single fact rewrites the whole public npm CDN landscape. The live contenders as of 2026 are jsDelivr, unpkg, cdnjs and esm.sh, and they differ far more than their URL shapes suggest. Below: a comparison table you can act on in 60 seconds, measured differences in cache behavior and ESM resolution, a workload decision matrix, the failover pattern that actually survives a public CDN outage, and a direct answer to the jsDelivr alternatives question. ![image-2](https://blog.blazingcdn.com/hs-fs/hubfs/Gemini%20INBlog%20Pictures/image.jpeg?width=1280&height=720&name=image.jpeg) ## **Best JavaScript CDN in 2026: the comparison table** | Capability | jsDelivr | unpkg | cdnjs | esm.sh | | --- | --- | --- | --- | --- | | Registry coverage | Full npm plus GitHub tags, WordPress plugins | Full npm, nothing else | Curated allowlist, roughly 4k libraries | Full npm, plus JSR and Deno paths | | ESM output | On demand via the plus-esm suffix | Only what the package ships; module query is legacy | Only what the package ships | Default; CJS-to-ESM transform, deep sub-path exports | | Type hints for editors | No | No | No | Yes, emits a types header pointing at declarations | | Delivery topology | Multi-CDN with DNS-level steering and health checks | Single provider fronting a small origin | Single provider, static object store origin | Single provider plus edge worker build cache | | SRI workflow | Hashes exposed in UI and API | Compute yourself | Hashes published per asset | Impractical: transform output can change | | Immutable caching on pinned versions | One year, immutable | One year, immutable | One year, immutable | One year on pinned build IDs; shorter on floating specs | | Compression | Brotli plus optional minification | gzip/Brotli, no minification | Brotli, pre-minified assets | Brotli, minified transform output | | Contractual SLA | None | None | None | None | Short version for 2026: jsDelivr remains the best JavaScript CDN for general-purpose public delivery, esm.sh is the best browser-native ESM resolver, cdnjs is the safest choice when you only need a handful of famous libraries with published hashes, and unpkg is a convenience layer for READMEs and CodePen. ## **unpkg vs jsDelivr: what actually differs at the edge** The URL syntax is nearly interchangeable, so teams assume the services are too. They are not. The difference is topology and what happens on a cache miss. jsDelivr fronts its public endpoint with multiple independent CDN providers and steers traffic at the DNS layer using continuous availability probes. When one provider degrades in a region, resolution shifts. That design has repeatedly meant jsDelivr rode out provider-specific incidents that took single-provider services offline. unpkg and cdnjs each sit behind one provider; if that provider has a regional control-plane problem, the asset is gone for those users and there is no second path. Cache-miss cost is the second divergence. Pinned, exact-version paths on all four services return an immutable one-year cache directive, so steady-state performance is dominated by edge hit ratio, not origin speed. The tail is where they separate. unpkg resolves unseen package paths against the registry and a modest origin, and cold requests for obscure packages have historically been its weakest point. jsDelivr's origin shield layer absorbs that. esm.sh has a third behavior entirely: a cold request for an untransformed package triggers a build at the edge, so first-byte time for a novel specifier can be an order of magnitude worse than a warm hit, then excellent afterwards. Practical rule as of 2026: never let a floating specifier like a latest tag or a caret range sit in a production HTML document. Floating specs on every one of these services get short TTLs, which means you pay revalidation on real user requests and you accept silent dependency mutation. ## **ESM support in 2026: esm.sh is doing something the others are not** Import maps are universally supported in current evergreen browsers, which finally makes bare-specifier imports in the browser practical without a bundler. That shifts the evaluation criteria for a JavaScript CDN from "can it serve a file" to "can it correctly resolve a package's exports field, sub-path exports, conditional exports, and its transitive CJS dependencies." esm.sh is the only one of the four that treats this as its primary job. It rewrites internal requires, honors conditional exports, supports pinning a dependency version across the whole transitive graph, and returns a header pointing at TypeScript declarations so editors resolve types from the CDN URL. That last detail matters more than it sounds: it is the difference between a browser-native workflow that autocompletes and one that does not. jsDelivr's plus-esm transform is solid for the common case of a single CJS library you want as a module. It is less predictable with packages that lean hard on conditional exports or Node built-ins. unpkg and cdnjs do no transformation at all โ€” you get ESM only if the maintainer shipped an ESM entry point, and for the long tail of older libraries that is still a coin flip. The trade-off nobody advertises: transformed ESM and Subresource Integrity are fundamentally in tension. An SRI hash binds to exact bytes. Transform output is a function of the service's build pipeline, which changes. If you require SRI on every external asset, you are choosing cdnjs or jsDelivr's untransformed file paths, and you are doing your own ESM bundling upstream. ## **jsDelivr alternatives: which one, for which workload** "jsDelivr alternative" is the top adjacent query, and the honest answer depends on why you are leaving. Three distinct reasons, three different answers. - **You need cleaner ESM resolution:** esm.sh. Better exports handling, type hints, transitive version pinning. - **You need published integrity hashes and a small, audited surface:** cdnjs. The curated allowlist is a feature, not a limitation. - **You need an actual uptime commitment because this asset is on a revenue path:** none of the four. You need your own edge in front of your own artifact store. ### The workload decision matrix for the best JavaScript CDN | Workload | Pick | Why | | --- | --- | --- | | OSS docs site, high traffic, no revenue risk | jsDelivr | Multi-CDN steering, GitHub tag support, best cold-tail behavior | | Bundler-free app, import maps, TypeScript | esm.sh | Correct exports resolution, type headers, graph-wide pinning | | Strict CSP with hash allowlist | cdnjs | Per-asset SRI published, stable bytes, small blast radius | | README example, CodePen, bug repro | unpkg | Shortest memorable URL; downtime is irrelevant here | | Checkout, player bootstrap, auth widget | Self-host behind a commercial CDN | Public CDNs offer no SLA; a third-party dependency in the critical path is an unpriced risk | | Internal dashboard, staff-only tooling | jsDelivr or cdnjs | Low stakes, zero operational cost | ## **Failure modes and the failover pattern that actually works** The common mitigation is a fallback that checks whether a global symbol exists after the primary script tag and injects a secondary URL if it does not. It works for classic scripts. It does not work for modules, because module loading is asynchronous and an import map has exactly one mapping per specifier. There is no built-in fallback for a failed module fetch. Three patterns that hold up in 2026, in increasing order of robustness: 1. **Import map plus service worker interception.** The worker catches a failed fetch for a CDN origin and retries against a second CDN with a rewritten path. Costs you a worker and a path-translation table, buys you real failover for modules. 2. **Preload plus origin fallback.** Preload the module from the public CDN, but map the specifier to your own origin path and have your edge proxy fetch from the public CDN with a long stale-while-revalidate window. The public CDN becomes your upstream, not your client's dependency. 3. **Vendor at build time, serve from your own edge.** No runtime third-party dependency at all. The dependency graph is resolved, audited and hashed before deploy. Pattern two is the one most teams should adopt, because it keeps the operational simplicity of a public CDN while moving the availability decision into infrastructure you control. Your edge holds the object; if the upstream public CDN is down, stale content still serves. That is where a commercial edge earns its keep. If you are proxying or hosting your own JavaScript bundles, the cost math is what determines whether the pattern survives a budget review. [**BlazingCDN's software delivery infrastructure**](https://blazingcdn.com/solutions-for-software-companies/) sits in the high-volume, cost-per-TB league alongside Bunny.net, CDN77, KeyCDN and Gcore rather than competing on Cloudflare's or Akamai's feature breadth, and it delivers stability and fault tolerance comparable to Amazon CloudFront at a materially lower cost, with 100% uptime, NVMe SSD edge storage, flexible cache configuration and roughly one-hour onboarding. Pricing is volume-based and predictable: starting at $5 per TB ($0.005 per GB) at entry volumes, $100/month for up to 25 TB with additional GB at $0.004, $350/month to 100 TB at $0.0035, $1,500/month to 500 TB at $0.003, $2,500/month to 1,000 TB at $0.0025, and $4,000/month to 2,000 TB at $0.002 per GB โ€” $2 per TB at the top tier. For a team serving 40 TB of static bundles and player assets monthly, that difference against a hyperscaler's list egress is usually the entire argument. Bunny.net is genuinely strong on entry-level simplicity and CDN77 on streaming tooling; the differentiator here is cost-per-TB at sustained volume plus configuration flexibility on cache keys and headers. ## **Security hygiene that changed in 2026** Pin exact versions. Not a tilde, not a caret, not a latest tag. Every supply-chain incident involving a public JavaScript CDN in recent years has depended on a floating specifier somewhere in the chain. Apply SRI to every untransformed asset, and understand what it does not cover: it validates bytes, not availability, and it does nothing for a compromised maintainer publishing a malicious version you then pin to. Pair it with a CSP that restricts script sources to specific CDN hostnames, and monitor maintainer changes on your direct dependencies. For transformed ESM endpoints where SRI is impractical, treat the CDN as trusted infrastructure and limit what you route through it โ€” which is another argument for vendoring anything on a revenue path. ## FAQ ### What is the best JavaScript CDN in 2026 for a production site? For public, non-revenue-critical assets, jsDelivr, because its multi-CDN steering gives it a failover path the single-provider services lack. For anything on a checkout, auth or player bootstrap path, none of the free public CDNs is appropriate โ€” they carry no SLA. Self-host and front it with a commercial CDN. ### Is Skypack still usable in 2026? Not reliably. Its build service has been effectively unmaintained, and newer package versions frequently fail to resolve or return stale transforms. If you have Skypack URLs in production, migrate them to esm.sh, which covers the same ESM-first use case with active maintenance and better exports handling. ### unpkg vs jsDelivr: which is faster? On warm, pinned, exact-version paths the difference is small because both return immutable one-year cache directives and performance is dominated by edge hit ratio. The gap opens on cold requests for less popular packages and during provider-specific incidents, where jsDelivr's multi-CDN routing and origin shield give it a meaningfully better tail. ### Can I use SRI with esm.sh? Not practically. SRI binds to exact bytes, and esm.sh output is generated by a build pipeline whose results can change between deploys, which would break the hash. If SRI is a hard requirement, use cdnjs or jsDelivr's untransformed file paths and handle ESM conversion in your own build. ### Do I still need a bundler if I use an npm CDN with import maps? For small apps and internal tools, no โ€” import maps plus esm.sh cover it. For large dependency graphs you will still want a bundler, because dozens of separate module fetches cost you request overhead and defeat tree-shaking even over HTTP/2 or HTTP/3. ### How do I fail over if a public JavaScript CDN goes down? Classic script tags can use a global-symbol check and inject a secondary URL. Modules cannot, because import maps allow only one mapping per specifier. The durable pattern is to map specifiers to your own origin and have your edge proxy the public CDN with a long stale-while-revalidate window, so cached objects keep serving when the upstream fails. ## Run this benchmark this week Pull your production HTML and grep every third-party script and module URL. For each one, answer three questions: is the version pinned exactly, does the response carry an immutable one-year cache directive, and is there a defined behavior if that hostname returns a non-200 for the next ten minutes. Anything that fails question three and sits above the fold is an unpriced availability dependency. Then measure the tail, not the median. Fetch each asset cold from three geographies you actually serve, and compare against the same object proxied through your own edge with stale-while-revalidate enabled. If the proxied path is within a few tens of milliseconds at p95, the failover argument makes itself. What is the least obvious third-party JavaScript dependency you found in your critical render path? 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The CDN for video and large traffic Their monthly bill vs ours - 20 TBFastly $2,087**$92.50** - 50 TBCDN77 $990**$215** - 200 TBCloudFront $11,965**$765** Published list prices, Aug 2026 [Calculate your cost](https://blazingcdn.com/cdn-cost-calculator/?utm_source=blog&utm_medium=sidebar&utm_campaign=blog_sidebar&utm_content=compare_calc) ## Related posts [![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-21-2026-07-30-27-5571-AM.jpeg)](https://blog.blazingcdn.com/en-us/tls-1-3-and-0-rtt-at-the-edge-the-real-handshake-cost?hsLang=en-us) Learn ### [TLS 1.3 and 0-RTT at the Edge: The Real Handshake Cost](https://blog.blazingcdn.com/en-us/tls-1-3-and-0-rtt-at-the-edge-the-real-handshake-cost?hsLang=en-us) TLS 1.3 removes exactly one round trip from a full handshake compared with TLS 1.2, and 0-RTT removes one more on ... Sep 21, 2026, 9:33:42โ€ฏAM [Read more](https://blog.blazingcdn.com/en-us/tls-1-3-and-0-rtt-at-the-edge-the-real-handshake-cost?hsLang=en-us) [![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-20-2026-07-30-23-3710-AM.jpeg)](https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop?hsLang=en-us) Learn ### [Anycast vs DNS Routing: How a CDN Picks the PoP](https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop?hsLang=en-us) Evaluated February 2026. Two mechanisms decide which edge serves a request, and they fail on completely different ... Sep 20, 2026, 9:33:54โ€ฏAM [Read more](https://blog.blazingcdn.com/en-us/anycast-vs-dns-routing-how-a-cdn-picks-the-pop?hsLang=en-us) [![](https://blog.blazingcdn.com/hubfs/Gemini-Blog/image-Sep-20-2026-07-00-33-3709-AM.jpeg)](https://blog.blazingcdn.com/en-us/understanding-cloudflares-rate-limiting-pricing?hsLang=en-us) Security ### [Cloudflare Rate Limiting Pricing 2026: Plans, Rules and Real Costs](https://blog.blazingcdn.com/en-us/understanding-cloudflares-rate-limiting-pricing?hsLang=en-us) Cloudflare Rate Limiting Pricing 2026: Plans, Rules, Real Costs Cloudflare rate limiting pricing has one detail that ... 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All rights reserved. ![](https://matomo.blazingcdn.com/matomo.php?idsite=1&rec=1) ```json { "@context" : "https://schema.org", "@id" : "https://blazingcdn.com/#organization", "@type" : "Organization", "description" : "High-volume CDN for video, live streaming, OTT/IPTV, software, games, SaaS and large-file delivery.", "logo" : { "@id" : "https://blazingcdn.com/#logo", "@type" : "ImageObject", "height" : 560, "url" : "https://blazingcdn.com/wp-content/uploads/2024/08/logo-560-560.png", "width" : 560 }, "name" : "BlazingCDN", "sameAs" : [ "https://www.linkedin.com/company/68261278", "https://x.com/BlazingCdn", "https://twitter.com/BlazingCdn", "https://www.facebook.com/BlazingCDN", "https://www.reddit.com/r/BlazingCDN/" ], "url" : "https://blazingcdn.com/" } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/#website", "@type" : "WebSite", "inLanguage" : "en-US", "name" : "BlazingCDN Blog", "publisher" : { "@id" : "https://blazingcdn.com/#organization" }, "url" : "https://blog.blazingcdn.com/" } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/choose-best-js-cdn-compare-npm-alternatives-skypack-jsdelivr-unpkg#article", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "BlazingCDN" }, "dateModified" : "2026-09-18T07:02:39Z", "datePublished" : "2026-09-18T07:02:39Z", "description" : "Which public JavaScript CDN is fastest and most reliable in 2026: jsDelivr, unpkg, cdnjs and esm.sh compared on speed, ESM support and caching.", "headline" : "Best JavaScript CDN in 2026: jsDelivr vs unpkg vs cdnjs vs esm.sh", "image" : "https://143144902.fs1.hubspotusercontent-eu1.net/hubfs/143144902/Gemini-Blog/image-Sep-18-2026-07-00-33-2719-AM.jpeg", "inLanguage" : "en-us", "isPartOf" : { "@id" : "https://blog.blazingcdn.com/#website" }, "mainEntityOfPage" : { "@id" : "https://blog.blazingcdn.com/en-us/choose-best-js-cdn-compare-npm-alternatives-skypack-jsdelivr-unpkg", "@type" : "WebPage" }, "publisher" : { "@id" : "https://blazingcdn.com/#organization" }, "wordCount" : 2238 } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/choose-best-js-cdn-compare-npm-alternatives-skypack-jsdelivr-unpkg#breadcrumb", "@type" : "BreadcrumbList", "itemListElement" : [ { "@type" : "ListItem", "item" : "https://blog.blazingcdn.com/en-us", "name" : "Blog", "position" : 1 }, { "@type" : "ListItem", "item" : "https://blog.blazingcdn.com/en-us/choose-best-js-cdn-compare-npm-alternatives-skypack-jsdelivr-unpkg", "name" : "Best JavaScript CDN in 2026: jsDelivr vs unpkg vs cdnjs vs esm.sh", "position" : 2 } ] } ``` ```json { "@context" : "https://schema.org", "@id" : "https://blog.blazingcdn.com/en-us/choose-best-js-cdn-compare-npm-alternatives-skypack-jsdelivr-unpkg#faq", "@type" : "FAQPage", "mainEntity" : [ { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "For public, non-revenue-critical assets, jsDelivr, because its multi-CDN steering gives it a failover path the single-provider services lack. For anything on a checkout, auth or player bootstrap path, none of the free public CDNs is appropriate โ€” they carry no SLA. Self-host and front it with a commercial CDN." }, "name" : "What is the best JavaScript CDN in 2026 for a production site?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Not reliably. Its build service has been effectively unmaintained, and newer package versions frequently fail to resolve or return stale transforms. If you have Skypack URLs in production, migrate them to esm.sh, which covers the same ESM-first use case with active maintenance and better exports handling." }, "name" : "Is Skypack still usable in 2026?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "On warm, pinned, exact-version paths the difference is small because both return immutable one-year cache directives and performance is dominated by edge hit ratio. The gap opens on cold requests for less popular packages and during provider-specific incidents, where jsDelivr's multi-CDN routing and origin shield give it a meaningfully better tail." }, "name" : "unpkg vs jsDelivr: which is faster?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Not practically. SRI binds to exact bytes, and esm.sh output is generated by a build pipeline whose results can change between deploys, which would break the hash. If SRI is a hard requirement, use cdnjs or jsDelivr's untransformed file paths and handle ESM conversion in your own build." }, "name" : "Can I use SRI with esm.sh?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "For small apps and internal tools, no โ€” import maps plus esm.sh cover it. For large dependency graphs you will still want a bundler, because dozens of separate module fetches cost you request overhead and defeat tree-shaking even over HTTP/2 or HTTP/3." }, "name" : "Do I still need a bundler if I use an npm CDN with import maps?" }, { "@type" : "Question", "acceptedAnswer" : { "@type" : "Answer", "text" : "Classic script tags can use a global-symbol check and inject a secondary URL. Modules cannot, because import maps allow only one mapping per specifier. The durable pattern is to map specifiers to your own origin and have your edge proxy the public CDN with a long stale-while-revalidate window, so cached objects keep serving when the upstream fails." }, "name" : "How do I fail over if a public JavaScript CDN goes down?" } ] } ```