--- title: Measuring the back/forward cache with Application Metrics description: Sentry has launched a new bfcacheMetricsIntegration, opt-in in JavaScript SDKs v11, that turns the browser's back/forward cache (bfcache) behavior into... canonical: https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Measuring the back/forward cache with Application Metrics | daily.dev og:description: Sentry has launched a new bfcacheMetricsIntegration, opt-in in JavaScript SDKs v11, that turns the browser's back/forward cache (bfcache) behavior into... og:url: https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa og:image: https://api.daily.dev/og/posts/ci8t6uIwA.png og:image:alt: Measuring the back/forward cache with Application Metrics og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Measuring the back/forward cache with Application Metrics **[Sentry Engineering](https://daily.dev/sources/sentry)** · 6 min read · 0 upvotes · 0 comments ## Summary Sentry has launched a new bfcacheMetricsIntegration, opt-in in JavaScript SDKs v11, that turns the browser's back/forward cache (bfcache) behavior into measurable application metrics. It tracks three metrics: navigation outcome (hit/miss), not-restored reasons (Chromium-only, via the notRestoredReasons API), and reload duration when a miss occurs. Because a bfcache hit produces no page load and leaves no trace in typical performance tooling, teams previously had no way to detect eligibility regressions caused by things like unload listeners, no-store headers, or iframe blockers. The integration lets teams build custom dashboards via agentic dashboard creation to track hit rates, top miss reasons, and problem routes. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How can I measure back/forward cache (bfcache) performance in my web app? Sentry's bfcacheMetricsIntegration, launched in JavaScript SDKs v11, models bfcache behavior as three application metrics: browser.bfcache.navigation (hit/miss outcome per navigation), browser.bfcache.not_restored (Chromium-only, one per disqualifying reason such as unload-listener or websocket), and browser.bfcache.reload.duration (the cost in milliseconds of a fallback reload on a miss). It is opt-in and enabled with a one-line integration call. _Track bfcache regressions and reload costs on daily.dev as new performance tooling for the back/forward cache emerges._ ### Why doesn't a bfcache hit show up in normal web performance monitoring tools? A bfcache hit produces no page load event, so tools built around the page-load lifecycle, including Core Web Vitals, never record it, making a healthy bfcache invisible in existing telemetry. Browser eligibility heuristics also shift over time, so pages can silently lose bfcache eligibility due to things like an unload listener, a Cache-Control: no-store header, an open connection, or an iframe blocker, with no error or crash to flag it. _Developers debugging silent performance regressions can follow bfcache-related coverage gaps on daily.dev._ ## Similar posts on daily.dev - [Chasing BFCache navigations](https://daily.dev/posts/chasing-bfcache-navigations-s4ehnks4b) · Web Performance Calendar · 1 upvotes · 0 comments - [The Blind Spot Between Back‐End Metrics and User Experience](https://daily.dev/posts/the-blind-spot-between-back-end-metrics-and-user-experience-h907tu8hy) · DevOps.com · 0 upvotes · 0 comments - [When Logout Isn’t Really Goodbye: A Subtle Data Exposure Bug.](https://daily.dev/posts/when-logout-isn-t-really-goodbye-a-subtle-data-exposure-bug--w3ugyb05d) · InfoSec Write-ups · 0 upvotes · 0 comments --- Tags: [#webdev](https://daily.dev/tags/webdev), [#javascript](https://daily.dev/tags/javascript), [#observability](https://daily.dev/tags/observability) [View this post on daily.dev](https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Measuring the back/forward cache with Application Metrics","url":"https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa"},"datePublished":"2026-09-24T18:58:59.213Z","dateModified":"2026-09-24T18:59:23.118Z","description":"Sentry has launched a new bfcacheMetricsIntegration, opt-in in JavaScript SDKs v11, that turns the browser's back/forward cache (bfcache) behavior into...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6ec757bca5ebd4b061beb262430ac887?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/6ec757bca5ebd4b061beb262430ac887?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Sentry Engineering","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Sentry Engineering","logo":"https://media.daily.dev/image/upload/s--qqXwMThM--/f_auto/v1710505439/logos/sentry","url":"https://daily.dev/sources/sentry"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"webdev,javascript,observability","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Sentry Engineering","item":"https://daily.dev/sources/sentry"},{"@type":"ListItem","position":3,"name":"Measuring the back/forward cache with Application Metrics"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/measuring-the-back-forward-cache-with-application-metrics-ci8t6uiwa#faq","mainEntity":[{"@type":"Question","name":"How can I measure back/forward cache (bfcache) performance in my web app?","acceptedAnswer":{"@type":"Answer","text":"Sentry's bfcacheMetricsIntegration, launched in JavaScript SDKs v11, models bfcache behavior as three application metrics: browser.bfcache.navigation (hit/miss outcome per navigation), browser.bfcache.not_restored (Chromium-only, one per disqualifying reason such as unload-listener or websocket), and browser.bfcache.reload.duration (the cost in milliseconds of a fallback reload on a miss). 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