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Vercel logoVercel · Feature trail

Redirects

22 posts · Oct 2019 – Sep 2026

What this trail covers

Vercel's platform can front any application, not just those deployed natively on the platform, providing firewall protection, DDoS mitigation, and observability. This includes using Vercel Web Analytics, Firewall, and Bot Management. Microfrontends allow for running multiple applications on a single domain, enabling incremental modernization by mounting different Vercel projects to specific route paths. This approach offers better isolation, independent environment variables, and organization. The platform now supports millions of static redirects per project with optimized lookup paths using sharded Bloom filters and binary search over sorted keys, significantly reducing latency and cost for large-scale redirect management.

All Vercel trails
  1. How we cut CDN metadata lookup latency by 91%Introduced indexed shards for CDN routing metadata, grouping path metadata into bounded files (approx. 200 KB) to improve cache hit rates and reduce latency. Implemented a binary search mechanism within shards using build-time byte offsets and Base64 encoded pointers for efficient lookup. Leveraged existing JSONL formats and incorporated learnings from Bloom filters and Bulk Redirects for data structure design. Conducted extensive production testing and shadow mode validation to ensure safety and measure performance improvements, achieving a 91% reduction in P99 metadata lookup latency.
  2. How we run Vercel's CDN in front of DiscourseThis post details how Vercel's CDN can be used as a proxy for external applications like Discourse, providing security (Firewall, Bot Management) and observability (Web Analytics) without requiring a full migration. It introduces the use of `vercel.ts` for rewrites to proxy traffic to an inner host with a `x-proxy-secret` header for validation. It also expands on the microfrontend approach by using `microfrontends.json` to mount separate Vercel projects to specific routes (e.g., `/live/:path*`, `/.well-known/workflow/:path*`) for better isolation, independent environment variables, and organization, enabling incremental modernization of parts of the application.
  3. Scaling redirects to infinity on VercelThis post details the engineering effort to scale Vercel's redirect system to millions of entries. It introduces a new architecture involving sharded Bloom filters and binary search over sorted keys within shards to optimize lookup performance and reduce memory usage. Key technical contributions include the shard structure (header, base64 encoded Bloom filter, JSON object of redirects), the lookup path leveraging Bloom filters for fast negative lookups and binary search for positive lookups to avoid full JSON parsing, and the resulting latency improvements and elimination of CPU-bound spikes.
  4. Security through design: Creating the improved Firewall experienceThe post details a redesign of the Vercel Firewall user interface to improve usability and provide better visibility into security events. Key improvements include a redesigned overview page with alerts, rules, events, and denied IPs feeds; a new traffic page with comprehensive intelligence on IPs, JA4 digests, AS names, user agents, request paths, and rules with most activity; dedicated tabs for Firewall Rules and Audit Log; and faster event inspection with a detailed view directly within the page. While the post focuses on UI/UX improvements for security tooling, it implies underlying system enhancements to provide this richer data and faster inspection, potentially related to how traffic data is processed and presented. However, it does not introduce new core system capabilities like sharding or Bloom filters for redirects, but rather enhances the user's interaction with existing security systems.
  5. How we made global routing faster with Bloom filtersIntroduced Bloom filters to the global routing service to optimize path lookups. This involved implementing matching Bloom filter logic in both the build and routing services, generating a smaller JSON Lines (JSONL) file for Bloom filter parameters and buffer, and decoding the Base64 encoded bit array directly for near-zero latency lookups. This optimization reduced memory usage by 15% and improved TTFB by 10% across the routing service.
  7. ISR on Vercel is now faster and more cost-efficientThis post details optimizations to Vercel's Incremental Static Regeneration (ISR) implementation. Key improvements include regionalized caching, where ISR cache entries are now stored in the same region as the associated functions, leading to lower latency for cache retrieval and faster revalidations. Additionally, automatic compression has been enabled for ISR cache entries, reducing write and read units, as well as Fast Origin Transfer (FOT) costs, resulting in up to 65% savings on ISR reads and writes. These improvements are automatically applied to existing deployments.
  8. How Vercel adopted microfrontendsThis post details Vercel's internal migration from a monolithic Next.js application to a vertical microfrontend architecture for its main website. It explains the rationale behind the migration (improving build times, developer velocity, and dependency management), the choice of vertical microfrontends over horizontal ones, and the incremental migration path using Next.js Multi-Zones and feature flags. The post highlights the benefits achieved, such as over 40% improvement in preview build times and local development compilation, and reduced page weight. It also touches upon leveraging Turborepo and Turbopack for build optimizations.
  9. Incremental Static Regeneration (ISR): A flexible way to cache dynamic contentThis post introduces Incremental Static Regeneration (ISR) as a caching strategy that combines static site generation (SSG) and server-side rendering (SSR) to deliver dynamic content at cached speeds. It details the benefits of ISR, including cached speeds with live content, selective regeneration, on-demand invalidation, and guaranteed cache durability. The post explains how ISR fits into Vercel's caching stack, alongside static assets, application-level caching, and client-side caching. It highlights framework adoption for ISR (Next.js, SvelteKit, Nuxt, Astro, Gatsby, Remix) and provides real-world scenarios in e-commerce, news websites, and AI-powered applications. The post also details implementation methods for ISR, including time-based regeneration with a SvelteKit example and on-demand regeneration with an Astro example using a bypass token and `x-prerender-revalidate` header.
  10. Why all application migrations should be incrementalThis post details incremental migration strategies, contrasting 'big bang' with 'incremental' approaches (vertical and horizontal). It highlights the trade-offs, particularly the interop effort versus risk reduction. For frontend migrations, it emphasizes the use of reverse proxies and Vercel's Edge Middleware for phased traffic migration. It also touches upon migrating from monolithic to composable architectures and the specific techniques for migrating web frontends using reverse proxies and gradual traffic shifting.
  11. Algolia cuts build times in half with ISR using Next.js on VercelAlgolia reduced build times by 50% by migrating to Next.js on Vercel, leveraging Incremental Static Regeneration (ISR) and Vercel Analytics. This improved their development cycle and enabled faster website changes.
  12. Incremental migration from WordPress for a dev-first approach | Customers | VercelThis post details how Gearbox uses Edge Middleware to incrementally adopt Next.js, managing blog redirects to maintain SEO by rewriting new posts to an existing WordPress blog under the hood, filtering traffic, and pointing to other services and websites while masking the URL and without complicated server setup. This allows for incremental migration in phases and management of scopes.
  13. How Vercel helps mmm.page manage over 30,000 sites | Customers | VercelThis post details how mmm.page migrated from an SPA on Amazon S3 to Vercel, leveraging Server-Side Rendering (SSR) for improved SEO and custom domain management. It highlights Vercel's ability to handle scale, monetize offerings, and innovate. The post also mentions Vercel's caching capabilities, which reduce database calls and improve performance for dynamic data. While the post doesn't introduce a new technical capability, it demonstrates the practical application and benefits of existing Vercel features like SSR and caching in a customer scenario.
  14. Replacing Google Optimize with the Vercel Edge NetworkThis post introduces the use of Vercel's Edge Network, specifically Edge Config and Routing Middleware, to implement high-performance A/B testing and personalization strategies as a replacement for Google Optimize. It details how Edge Config provides sub-millisecond configuration read times and how Routing Middleware can serve correct page variants instantly to eliminate Cumulative Layout Shift (CLS). It also provides an example of tracking experiment results using a `saveData` function.
  15. Introducing Edge Config: Globally distributed, instant configurationIntroduced Vercel Edge Config, a globally distributed, ultra-low latency data store for configuration data. It enables near-instant reads (5ms or less for most lookups) by pushing data to every Vercel region. Key use cases include A/B testing, feature flags, dynamic redirects, and request blocking rules. Announced integrations with Statsig and HappyKit for feature flagging and A/B testing at the edge. Provided an Edge Config SDK and examples for integration.
  16. Edge Config: Ultra-low latency data at the edgeIntroduced Edge Config, a globally distributed, ultra-low latency data store for configuration data. It enables near-instant reads of configuration data from Edge Middleware, Edge Functions, and Serverless Functions. Optimized for fast, inexpensive reads and infrequent writes, with data replicated to all regions before request. Supports A/B testing, feature flags, dynamic redirects, and request blocking rules. Provides an API for querying data and integrates with Statsig and HappyKit.
  17. How to run A/B tests with Next.js and VercelThis post details the implementation of A/B testing for Vercel's Templates page using Next.js Edge Middleware. It explains how Edge Middleware can be used to perform rewrites at the edge to serve different variants of a page to different users, thereby avoiding client-side layout shifts. The post also covers the use of catch-all routes and on-demand revalidation for dynamic page generation and how to conditionally render skeleton loaders to further improve user experience during data fetching.
  18. Hashicorp uses ISR to iterate faster on VercelThis post introduces on-demand Incremental Static Regeneration (ISR) for Next.js, allowing for selective cache invalidation of specific pages via an API call. It details how HashiCorp uses ISR for managing documentation content at scale, deferring generation of less-visited pages and propagating content changes without full rebuilds. The integration with GitHub Actions and Vercel deploy hooks for triggering on-demand ISR based on file changes is also discussed.
  19. 10 Next.js tips you might not knowThis post introduces Next.js Redirects, a feature introduced in version 9.5, allowing rerouting of incoming request paths to other destinations. It details configuration via `next.config.js` with support for path matching, regex path matching, and wildcard paths, providing a code example for permanent redirects.
  20. RedirectsThis post introduces the concept of Vercel's platform being able to front any application, not just those deployed natively. It highlights the provision of firewall protection, DDoS mitigation, and observability. It also touches upon the use of Vercel Web Analytics, Firewall, and Bot Management. The concept of microfrontends is introduced as a way to run multiple applications on a single domain, enabling incremental modernization by mounting different Vercel projects to specific route paths. This approach offers better isolation, independent environment variables, and organization.