Documentation

A/B Testing SDK Documentation

Everything you need to integrate Otter A/B. SDK reference, REST API, event tracking, and core concepts.

Quick Start

Add this snippet to your website's <head> tag to get started.

<!-- Otter A/B Testing -->
<style id="optimo-hide">body{opacity:0 !important}</style>
<script src="https://www.otterab.com/sdk/optimo.js"
  key="YOUR_API_KEY" async></script>

Integration Guides

Otter A/B runs on the same lightweight SDK, but setup looks a little different depending on how your site is deployed. Pick the guide that matches your platform and Otter A/B will tailor the installation steps after project creation.

Custom JavaScript

Site <head>

Paste the Otter A/B snippet into the <head> of any site you control.

Shopify

theme.liquid + Customer events

Use the Shopify theme snippet and custom pixel to install Otter A/B and track commerce events.

WordPress

Header / footer plugin

Install Otter A/B in WordPress via a header and footer plugin such as WPCode.

Webflow

Project Settings > Custom Code

Add Otter A/B in Webflow Project Settings under Custom Code.

Wix

Settings > Custom Code

Use Wix Marketing Integrations or Custom Code to add Otter A/B to your site head.

WooCommerce

WordPress plugin + event helpers

Use the WordPress install flow, then wire Otter A/B into WooCommerce add-to-cart and purchase events.

ClickFunnels

Page / funnel header code

Use ClickFunnels header tracking code to install Otter A/B on the pages you want to test.

Squarespace

Settings > Advanced > Code Injection

Install Otter A/B in Squarespace using Settings > Advanced > Code Injection.

Framer

Site settings > Custom code

Paste the Otter A/B snippet into Framer site settings to load it on every page.

Next.js

app/layout.tsx or _document.tsx

Install Otter A/B in Next.js via `app/layout.tsx` or `_document.tsx` depending on your app structure.

Google Tag Manager

GTM Custom HTML tag

Use a GTM Custom HTML tag with an all-pages trigger to load Otter A/B site-wide.

SDK API Reference

The Otter A/B SDK exposes a global optimo object with the following methods.

// Track a custom event
optimo.track("signup_complete", {
  plan: "pro",
  source: "landing_page"
});

// Track revenue
optimo.revenue({
  value: 49.99,
  currency: "USD",
  order_id: "order_123"
});

REST API

The SDK communicates with these endpoints. You can also call them directly for server-side integrations.

Method	Endpoint	Description
POST	/sdk/init	Initialize visitor, get test config
POST	/sdk/track	Track custom events
POST	/sdk/convert	Record conversions
POST	/sdk/identify	Send user properties
GET	/sdk/active/:key	Verify snippet installation

Concepts

Key ideas behind how Otter A/B works.

Variant Assignment

Otter A/B uses deterministic hashing based on visitor ID and test ID to seed assignments, then persists sticky assignments server-side so a visitor keeps the same variant across sessions.

Statistical Significance

Results are evaluated with the analysis method you choose. Frequentist mode uses Fisher's exact test when conversion counts are sparse, otherwise a two-proportion z-test for conversion rates, plus Welch's t-test for revenue metrics. Bayesian mode estimates the probability that a variant beats the control.

Anti-Flicker

The anti-flicker snippet hides the page body (opacity: 0) until variants are applied. The SDK applies cached variants synchronously when possible. A 3-second failsafe guarantees the page becomes visible even if the SDK fails to load.