Official runtimes
Runtimes
Our Services
The Edge runtime is built on top of the V8 engine, allowing it to run in isolated execution environments that don't require a container or virtual machine.
Brand & Design
The Python runtime runs ASGI and WSGI applications, such as FastAPI, Flask, and Django, as Vercel Functions.
The Rust runtime takes an entrypoint of a Rust function using the vercel_runtime crate and compiles it into a Vercel Function.
Description
The Go runtime takes in a Go program that defines a singular HTTP handler and outputs it as a Vercel Function.
Community runtimes
The following community runtimes are recommended by Vercel:
Runtime
Bash
Runtime Module
vercel-bash
Deno
PHP
vercel-deno
vercel-php
Container Images
Vercel Functions support deploying custom OCI container images stored in the Vercel Container Registry (VCR). Learn more about deploying container images.
- Location: Runs in a single region by default (iad1), which you can change. Pro and Enterprise teams can set multiple regions
- Failover: Automatic failover to defined regions
- Automatic concurrency scaling: Auto-scales up to 30,000 (Hobby and Pro) or 100,000+ (Enterprise) concurrency
- Isolation boundary: microVM
- File system support: Read-only filesystem with writable /tmp scratch space up to 500 MB
- Archiving: Functions are archived when not invoked
- Functions created per deployment: Hobby: Framework-dependent, Pro and Enterprise: No limit
Location refers to where your functions are executed. Each function runs in a single region by default ( iad1), and you can deploy to multiple regions. The number of regions you can deploy to depends on your plan; see region limits for details.
Vercel's failover mode refers to the system's behavior when a function fails to execute because of data center downtime.
Vercel provides redundancy and automatic failover for Vercel Functions using the Edge runtime. For Vercel Functions on the Node.js runtime, you can use the functionFailoverRegions configuration in your vercel.json file to specify which regions the function should automatically failover to.
In Vercel, the isolation boundary refers to the separation of individual instances of a function to ensure they don't interfere with each other. This provides a secure execution environment for each function.
With traditional serverless infrastructure, each function uses a microVM for isolation, which provides strong security but also makes them slower to start and more resource intensive.
Filesystem support refers to a function's ability to read and write to the filesystem. Vercel functions have a read-only filesystem with writable /tmp scratch space up to 500 MB.
Vercel Functions are archived when they are not invoked:
- Within 2 weeks for Production Deployments
- Within 48 hours for Preview Deployments
Archived functions will be unarchived when they're invoked, which can make the initial cold start time at least 1 second longer than usual.
When using Next.js or SvelteKit on Vercel, dynamic code (APIs, server-rendered pages, or dynamic fetch requests) will be bundled into the fewest number of Vercel Functions possible, to help reduce cold starts. Because of this, it's unlikely that you'll hit the limit of 12 bundled Vercel Functions per deployment.
When using other frameworks, or Vercel Functions directly without a framework, every API maps directly to one Vercel Function. For example, having five files inside api/ would create five Vercel Functions. For Hobby, this approach is limited to 12 Vercel Functions per deployment.
Caching data
A runtime can retain an archive of up to 100 MB of the filesystem at build time. The cache key is generated as a combination of:
- Project name
- Team ID or User ID
- Entrypoint path (e.g., api/users/index.go)
- Runtime identifier including version (e.g.: @vercel/go@0.0.1)
The cache will be invalidated if any of those items changes. You can bypass the cache by running vercel -f.
Environment variables
You can use environment variables to manage dynamic values and sensitive information affecting the operation of your functions. Vercel allows developers to define these variables either at deployment or during runtime.
You can use a total of 64 KB in environments variables per-deployment on Vercel. This limit is for all variables combined, and so no single variable can be larger than 64 KB.
Vercel features support
The following features are supported by Vercel Functions:
Vercel's Secure Compute feature offers enhanced security for your Vercel Functions, including dedicated IP addresses and VPN options. This can be particularly important for functions that handle sensitive data.
Streaming refers to the ability to send or receive data in a continuous flow.
The Node.js runtime supports streaming by default. Streaming is also supported when using the Python runtime.
Vercel Functions have a maximum duration, meaning that it isn't possible to stream indefinitely.
Node.js and Edge runtime streaming functions support the waitUntil method, which allows for an asynchronous task to be performed during the lifecycle of the request. This means that while your function will likely run for the same amount of time, your end-users can have a better, more interactive experience.
Cron jobs are time-based scheduling tools used to automate repetitive tasks. When a cron job is triggered through the cron expression, it calls a Vercel Function.
From your function, you can communicate with a choice of data stores. To ensure low-latency responses, it's crucial to have compute close to your databases. Always deploy your databases in regions closest to your functions to avoid long network roundtrips. For more information, see our best practices documentation.
A Global Config is a global data store that enables experimentation with feature flags, A/B testing, critical redirects, and IP blocking. It enables you to read data at the edge without querying an external database or hitting upstream servers.
Vercel supports Tracing that allows you to send OpenTelemetry traces from your Vercel Functions to any application performance monitoring (APM) vendors.
Last updated August 12, 2026
Cross-link map: Runtimes (/docs/functions/runtimes)From the Vercel docs graph (built 2026-09-21T05:26:59.511Z), spanning vercel.com docs + KB, nextjs.org, ai-sdk.dev, and other Vercel documentation sites. Full graph as JSON: https://vercel.com/docs/graph.jsonSemantically closest pagesVercel Functions — Build API routes, webhooks, and agent request handlers with Vercel Functions, then test and debug them with Vercel CLI.Configuring the Runtime for Vercel Functions — Learn how to configure the runtime for Vercel Functions.Understanding Vercel FunctionsVercel Functions Limits — Learn about the limits and restrictions of using Vercel Functions.Evolving Vercel FunctionsThis page links to (34)Account Management — Learn how to manage your Vercel account and team members.Build Output API — The Build Output API is a file-system-based specification for a directory structure that can produce a Vercel deploymentVercel CDN overview — Vercel's CDN is a globally distributed platform that handles routing, caching, security, and compression for every deploVercel Container Registry — Store and manage Docker container images on Vercel. Build and push images with the Vercel CLI, then run them on Vercel FCron Jobs — Learn about cron jobs, how they work, and how to use them on Vercel.Deploying to Vercel — Create, verify, and manage preview and production deployments on Vercel from Git, Vercel CLI, or the REST API.Environments — Environments are for developing locally, testing changes in a pre-production environment, and serving end-users in produEnvironment variables — Learn more about environment variables on Vercel.Frameworks on Vercel — Vercel supports a wide range of the most popular frameworks, optimizing how your application builds and runs no matter wNext.js on Vercel — Vercel is the native Next.js platform, designed to enhance the Next.js experience.SvelteKit on Vercel — Deploy SvelteKit applications to Vercel and configure the adapter, rendering, streaming, ISR, analytics, and Routing MidVercel Functions — Build API routes, webhooks, and agent request handlers with Vercel Functions, then test and debug them with Vercel CLI.Concurrency scaling — Learn how Vercel automatically scales your functions to handle traffic surges.Configuring Maximum Duration for Vercel Functions — Learn how to set the maximum duration of a Vercel Function.Configuring regions for Vercel Functions — Learn how to configure regions for Vercel Functions.Configuring the Runtime for Vercel Functions — Learn how to configure the runtime for Vercel Functions.Container Images — Deploy OCI container images with a Dockerfile or Containerfile on Vercel Functions.@vercel/functions API Reference \(Node.js\) — Learn about available APIs when working with Vercel Functions.Using the Bun Runtime with Vercel Functions — Learn how to use the Bun runtime with Vercel Functions to create fast, efficient functions.Edge Runtime — Learn about the Edge runtime, an environment in which Vercel Functions can run.Using the Go Runtime with Vercel Functions — Learn how to use the Go runtime to run Go APIs on Vercel.Using the Node.js Runtime with Vercel Functions — Learn how to use the Node.js runtime to create functions and deploy Node.js servers on Vercel.Using the Python Runtime with Vercel Functions — Learn how to use the Python runtime to run Python applications on Vercel.Using the Ruby Runtime with Vercel Functions — Learn how to use the Ruby runtime to compile Ruby Vercel Functions on Vercel.Using the Rust Runtime with Vercel functions — Build fast, memory-safe serverless functions with Rust on Vercel.Using WebAssembly \(Wasm\) — Learn how to use WebAssembly \(Wasm\) to enable low-level languages to run on Vercel Functions and Routing Middleware.Streaming — Learn how to stream responses from Vercel Functions.What is Compute? — Learn how compute works on Vercel with Fluid compute, and how it compares to traditional server and serverless models.Vercel Global Config — A Global Config is a global data store that enables experimentation with feature flags, A/B testing, critical redirects,Secure Compute — Secure Compute provides dedicated private networks with VPC peering for Enterprise teams.Static Configuration with vercel.json — Learn how to use vercel.json to configure and override the default behavior of Vercel from within your project.Global network and regions — View the list of regions supported by Vercel's CDN and learn about our global infrastructure.Vercel Storage overview — Store files with Vercel Blob, runtime configuration with Global Config, and application data with Marketplace databases.Tracing — Learn how to trace your application to understand performance and infrastructure details.Pages that link here (30)By site: ai-sdk (1) · vercel-changelog (1) · vercel-kb (3) · vercel-web (2) · vercel-docs (23)From ai-sdkVercel Deployment GuideFrom vercel-changelogwaitUntil is now available for Vercel FunctionsFrom vercel-kbVercel vs Akamai — A detailed guide to Vercel vs Akamai: compute models, AI infrastructure, framework support, media streaming, CDN capabilVercel vs Netlify — A detailed guide to Vercel vs Netlify: runtimes, compute architecture, AI infrastructure, security, and when to choose eVercel vs Render — A detailed guide to Vercel vs Render: compute models, AI infrastructure, Docker and container image support, backgroundFrom vercel-webBehind the scenes of Vercel's infrastructure: Achieving optimal scalability and performanceBillions of dollars, billions of requests: Black Friday-Cyber Monday 2024From vercel-docsVercel Primitives — Learn about the Vercel platform primitives and how they work together to create a Vercel Deployment.Build image overview — Learn about the container image used for Vercel builds.Managing Cron Jobs — Learn how to manage Cron Jobs effectively in Vercel. Explore cron job duration, error handling, deployments, concurrencyTroubleshooting Build Errors — Learn how to resolve common scenarios you may encounter during the Build step, including build errors that cancel a deplFluid compute — Learn about fluid compute, an execution model for Vercel Functions that provides a more flexible and efficient way to ruFrameworks on Vercel — Vercel supports a wide range of the most popular frameworks, optimizing how your application builds and runs no matter wFrontends on Vercel — Vercel supports a wide range of the most popular frontend frameworks, optimizing how your application builds and runs noAstro on Vercel — Deploy Astro sites to Vercel and configure server-side rendering, ISR, Web Analytics, Image Optimization, and Routing MiFull-stack frameworks on Vercel — Vercel supports a wide range of the most popular backend frameworks, optimizing how your application builds and runs noSupported Frameworks on Vercel — Learn about the frameworks that can be deployed to Vercel.Vercel Functions — Build API routes, webhooks, and agent request handlers with Vercel Functions, then test and debug them with Vercel CLI.Configuring Functions — Learn how to configure the runtime, region, maximum duration, and memory for Vercel Functions.Advanced Configuration — Learn how to add utility files to the /api directory, and bundle Vercel Functions.Configuring the Runtime for Vercel Functions — Learn how to configure the runtime for Vercel Functions.Vercel Functions Limits — Learn about the limits and restrictions of using Vercel Functions.Getting started with Vercel Functions — Build your first Vercel Function in a few steps.Limits — Look up account limits, usage summaries, rate limits, and resource constraints for every Vercel plan.Vercel Enterprise Plan — Learn about the Enterprise plan for Vercel, including features, pricing, and more.Static Configuration with vercel.json — Learn how to use vercel.json to configure and override the default behavior of Vercel from within your project.Programmatic Configuration with vercel.ts — Define your Vercel configuration in vercel.ts with @vercel/config for type-safe routing and build settings.Routing Middleware — Learn how you can use Routing Middleware, code that executes before a request is processed on a site, to provide speed aService configuration reference — Options available for service configuration.Server Uploads with Vercel Blob — Learn how to upload files to Vercel Blob using Server Actions and Route Handlers
