---
title: "Vercel Edge Config vs Landtest for A/B Testing"
description: "Edge Config gives you the lowest-latency, zero-flicker split if you're all-in on Vercel. Landtest trades some of that latency edge for not owning the split logic at all."
canonical: https://landtest.dev/blog/vercel-edge-config-vs-landtest
last-updated: 2026-10-30
---

# Vercel Edge Config vs Landtest for A/B Testing

> Edge Config gives you the lowest-latency, zero-flicker split if you're all-in on Vercel. Landtest trades some of that latency edge for not owning the split logic at all.

Vercel Edge Config paired with Edge Middleware assigns A/B test variants at the edge before the response is sent, which means zero client-side flicker and sub-15ms P99 reads — but the split logic lives in your `middleware.ts`, and it only works cleanly if you're deployed on Vercel. Landtest runs the split at the deploy/hosting layer against your repo's branches instead of inside a request handler, works regardless of host, and removes the split configuration entirely when you declare a winner. Both solve flicker; they differ in where the logic lives and how platform-dependent the approach is.

This is Landtest's own comparison content. Last updated 2026-09-30.

## What Edge Config does well

If your whole stack is on Vercel, this is about as fast as variant assignment gets. [Vercel's own zero-CLS experiment guide](https://vercel.com/blog/zero-cls-experiments-nextjs-edge-config) documents reads completing within 15ms at P99 for the vast majority of requests, and because assignment happens in middleware before the page renders, there's no flash of the control variant followed by a swap — the correct variant is what gets sent in the first place. For a team fully committed to Vercel's platform, this is a legitimate reason not to look elsewhere.

## Where the two diverge

**Platform dependency.** Edge Config's zero-flicker guarantee is specific to Vercel's edge runtime. If you ever move hosts, or you're running a hybrid setup, the approach doesn't transfer. Landtest's split runs through your deploy pipeline regardless of which host serves the page.

**Where the logic lives.** Edge Config still means writing and maintaining variant-assignment code in `middleware.ts` — the same file that's often already handling auth (Clerk, NextAuth) and locale routing. See [A/B testing without middleware conflicts](/blog/ab-test-nextjs-landing-page-without-middleware-conflicts) for why that composition gets messy. Landtest doesn't touch `middleware.ts` at all; the split happens outside your application's request-handling code entirely.

**Variant creation.** Edge Config assumes you've already built variant B — it's an assignment and config layer, not a code generator. Landtest's AI generates the variant as a branch against your actual codebase, with a live preview to review before it ships.

**Cleanup.** With Edge Config, removing a finished test means manually pulling the assignment logic and the losing code path back out of middleware and your components. Landtest produces a cleanup PR that strips the beacon, split config, and losing branch back to a bare `page.tsx`.

## Which one to pick

Choose Edge Config if you're Vercel-committed, want the absolute lowest possible latency, and are comfortable owning the middleware composition yourself. Choose Landtest if you want to avoid adding to `middleware.ts` at all, want the variant generated rather than hand-built, or you're not exclusively on Vercel.

## FAQ

**Does Edge Config cause flicker?**
No — that's its main advantage. Assignment happens server-side at the edge before the response renders, so the control version never displays before swapping.

**Is Edge Config free?**
Edge Config is part of Vercel's platform pricing; check Vercel's current plan pricing for specifics, as it's tied to your overall Vercel usage rather than priced as a standalone product.

**Can I use Edge Config if I'm not hosted on Vercel?**
No — it's a Vercel-specific product. For a host-agnostic split, Landtest or a self-hosted tool like GrowthBook are the options.

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Related: [Best A/B testing tools for Next.js developers](/blog/best-ab-testing-tools-nextjs-developers) · [A/B test without middleware conflicts](/blog/ab-test-nextjs-landing-page-without-middleware-conflicts) · [Landtest for A/B testing](/ab-testing)