evolveAB vs PostHog Experiments
Short version: PostHog is a whole product toolkit (analytics, session replay, feature flags and a lot more), and experiments are one part of it. If you already use PostHog for analytics, its experiments are the easy choice: same events, same dashboards, and 1 million free flag requests a month. evolveAB runs A/B tests and bandits on Next.js App Router pages, keeps raw events in your own Postgres, has an AI write variants within your rules, and sends winners back as pull requests.
We make evolveAB, so read this with that in mind. Every PostHog claim below links PostHog's own pages, checked on November 11, 2026. If something has changed, write to hello@evolveab.com and we'll fix it.
#Side by side
| PostHog Experiments | evolveAB | |
|---|---|---|
| What it is | Experiments built on PostHog feature flags, inside a suite with product analytics, session replay and more (docs) | A/B tests and bandits for UI regions in a Next.js App Router app |
| Price | Billed as feature flag requests: first 1,000,000 a month free, then $0.000100 per request (1M to 2M), falling to $0.000010 above 50M. "No per-seat charges" (pricing) | Free (1 site, 2 running experiments, 50,000 tested page views a month). Pro $149 per site per month. Growth $499 per month. 30-day free trial |
| Statistics | "Bayesian (default) or frequentist" (docs) | Bayesian; Thompson-sampling bandits |
| Flicker | Code experiments: evaluate on the server and bootstrap the client, which "prevents flicker" when server and client use the same distinct ID (docs). No-code experiments "change HTML after the page loads" (docs) | Variant chosen in proxy.ts and rendered on the server; no client-side changes |
| Where event data lives | PostHog Cloud, in the US (Virginia) or the EU (Frankfurt) (PostHog EU) | Your Postgres; our cloud receives per-variant counts and sums only |
| Self-hosting | A free Docker Compose "hobby" deploy under MIT; PostHog calls self-hosted deployments "officially unsupported" (docs) | The SDK runs in your app; the cloud is hosted only |
| No-code editing | Toolbar-built web experiments (docs) | Variants are prop values in the dashboard, checked against the component's Zod schema; an AI can write them |
| Ending a test | You remove the flag and code | A pull request commits the winner; the experiment archives itself after the deploy (Growth plan and trial) |
| Other products | Analytics, session replay, surveys, error tracking and more on the same account (pricing) | None. Pair it with whatever analytics you use |
#Where the data goes
With PostHog, your events (page views, clicks, the properties you attach) live in PostHog Cloud, in the region you choose. That's how its analytics, replay and experiments share one dataset, and it's a fair trade for most teams.
With evolveAB, events go from the visitor's browser to an API route on your own site, which writes them to your Postgres. Our cloud never connects to your database; it asks your app, over a signed request, for counts and sums per experiment, variant, goal and day. Visitor ids, IP addresses, user agents and individual events stay on your server. That matters if a privacy review or procurement form is holding up your testing. If not, PostHog's single dataset is probably worth more to you.
#Flicker
PostHog's no-code web experiments change the page in the browser after it loads; PostHog's docs say you'll "see a brief delay" when you evaluate the flag on the same page, and suggest evaluating it on the server and bootstrapping. Done that way, a PostHog code experiment is server-rendered too. In PostHog you wire the server evaluation and bootstrapping yourself; npx next-evolve init sets up the proxy and the cached render per variant for you.
#What we don't do
- Product analytics or session replay. We measure the goals you define for experiments, nothing else.
- Feature flags. We test UI regions on pages, not code paths.
- A free tier as large as PostHog's. Our Free plan has 2 running experiments and 50,000 tested page views a month.
- Frequentist analysis. Bayesian only.
- Anything outside the Next.js App Router. No Pages Router, no mobile, no other frameworks.
- A long track record. Sign-up opened in November 2026.
#When to pick PostHog
- You already use PostHog for analytics and want experiments on the same events.
- You want session replay and flags from the same vendor as your analytics.
- You need frequentist results, or you test in apps that aren't Next.js App Router.
- You're cost-sensitive at low volume: 1 million flag requests a month free covers a lot of small sites.
#When to pick evolveAB
- Visitor data has to stay on your own infrastructure, and a vendor-hosted event store is a blocker.
- You're testing marketing pages on the App Router and want flicker-free serving without wiring bootstrapping yourself.
- You want an AI to keep writing challengers within limits, and bandits to move traffic to the leader.
- You want the winner shipped as a pull request.
Start a 30-day free trial, no card needed, or read what leaves your server, call by call. Background on server-side testing with any tool: our Next.js A/B testing guide.
#Questions
#How much do PostHog experiments cost?
PostHog bills experiments as feature flag requests. The first 1,000,000 requests a month are free, then $0.000100 per request from 1 to 2 million, falling with volume to $0.000010 above 50 million, with no per-seat charges, according to PostHog's experiments pricing page (checked November 11, 2026).
#Do PostHog experiments flicker in Next.js?
Code experiments don't have to: PostHog's docs say evaluating flags on the server and bootstrapping the client prevents flicker as long as the server and client use the same distinct ID. No-code web experiments change HTML after the page loads, and the docs mention a brief delay when you evaluate the flag on the same page.
#Where does PostHog store experiment data?
In PostHog Cloud, in the US or the EU region you choose. PostHog also offers a free self-hosted hobby deployment under the MIT licence, which it describes as officially unsupported. evolveAB stores raw events in your own Postgres and its cloud receives only per-variant counts and sums.
#When is PostHog the better choice?
When you already use PostHog for analytics, want session replay from the same vendor, need frequentist statistics, or want the larger free tier. evolveAB only does A/B tests and bandits for the Next.js App Router.