In-depth: PostHog vs Optimizely

PostHog and Optimizely are both multi-product tools to help you improve your apps and websites. Beyond experimentation and feature flags, they have significantly different focuses:

• PostHog helps you build better products with tools like product analytics, session replay, and surveys.

• Optimizely is an all-in-one system for marketing that includes content management, campaign planning, asset management, and checkout customizations.

This post compares their platforms, experimentation features, reporting, pricing, and more.

How is PostHog different than Optimizely?

1. Product and startup-focused

PostHog is built for high-growth startups working to build the best possible products. It's easy to get started and provides all the tools you need at an early stage. There's a generous free plan and startups get free credits.

Optimizely focuses on providing marketing, ecommerce, and content tools to massive enterprises. It has fewer product focused tools.

2. Transparent, free, and self-service

PostHog is open source. Everything from our code to roadmap to strategy is open for everyone to see.

Along with this, you can sign up for PostHog for free. You don’t need to fill out a contact form, add a credit card, or have a sales call. You can use PostHog for free forever if you want.

Optimizely is open about some areas, like roadmap and its SDKs, but you have to talk to sales before signing up.

3. Analytics and reporting built-in

PostHog links all its tools together. This means you get all the features and visualizations of product analytics for your feature flags and A/B tests. You can use them in trends, funnels, and even directly query related metrics with SQL.

Optimizely has some analytics, such as web marketing, but largely relies on Google Analytics for tracking and reporting. This limits the analysis you can do related to your feature flags and experiments.

Platform

Although both Optimizely and PostHog provide experimentation and feature flags, their overall platforms are significantly different.

• The big platform difference between the two beyond marketing vs product features is analytics. Optimizely relies on external analytics providers like Google and Adobe Analytics to track feature flags and A/B tests. PostHog has a full analytics suite built-in, including autocapture, custom events, direct SQL access, and more.

• Being a marketing-focused platform, Optimizely includes project and content management tools like request forms, asset libraries, and hypothesis briefs. PostHog leaves the planning to the other tools you are using but does include notebooks for analysis.

Web experimentation

Optimizely splits its experimentation features into two separate categories, web and feature. We will compare both separately against PostHog.

The core web experimentation features like traffic allocation, preview mode, cross-browser, dynamic website support, targeting, and more are available in both Optimizely and PostHog

• In Optimizely, many features of web experiments, like scheduling, multi-armed bandits, multi-variate testing, and advanced personalization are only available on the higher-tier "Accelerate" plan or as add-ons.

• PostHog doesn't offer a no-code experiment creator yet, but it does have a UI to create and manage experiments as well as snippets to make it easy to implement them. For example, you can add a basic experiment anywhere you can insert custom JavaScript like this:

<script>
  !function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.crossOrigin="anonymous",p.async=!0,p.src=s.api_host+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="capture identify alias people.set people.set_once set_config register register_once unregister opt_out_capturing has_opted_out_capturing opt_in_capturing reset isFeatureEnabled onFeatureFlags getFeatureFlag getFeatureFlagPayload reloadFeatureFlags group updateEarlyAccessFeatureEnrollment getEarlyAccessFeatures getActiveMatchingSurveys getSurveys getNextSurveyStep".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);
  posthog.init('<ph_project_api_key>',{api_host:'https://us.i.posthog.com', defaults:'2025-05-24'})
  
  posthog.onFeatureFlags(() => {
    // Check the value of the 'test-flag' feature flag
    if (posthog.getFeatureFlag('test-flag') === 'test') {
      // If the feature flag is enabled, change the text of the landing-header
      const landingHeader = document.getElementById('landing-header');
      if (landingHeader) {
        landingHeader.textContent = "Welcome to our site!";
      }
    }
  });
</script>

Feature experimentation

Feature experimentation relates to releasing and testing feature changes in your product. Both Optimizely and PostHog have all the core features to do this safely and effectively.

In Optimizely, many of the feature experimentation features, like multi-armed bandits and custom segmentation, are only available in higher tier plans. These are all available for free in PostHog.

Pricing

PostHog and Optimizely are very different here. Optimizely is sales-driven and completely opaque. PostHog is self-serve and transparent.

For many Optimizely products, there are also paid add-ons like advanced personalization, the data platform, and their Salesforce integration. PostHog only has free and paid tiers for each product with a single enterprise add-on for SSO, dedicated support, and advanced permissions.

Reporting

Although Optimizely has web analytics through its content marketing platform, it relies on Google Analytics or other third-party analytics providers for advanced tracking and reporting.

PostHog’s product analytics suite shines here. It treats feature flags and experiments as usage, so you can analyze them like any other user behavior. On top of standard experiment results, you can use visualizations like trends, funnels, user paths, and even direct SQL access.

Another bonus of PostHog is the ability to view user sessions related to feature flags and experiments. You can see directly how they respond to new features and changes as well as how it affects the rest of their session.

SDKs and API

PostHog and Optimizely both support similar languages and frameworks with SDKs, as well as provide an API for interacting with data.

Integrations

PostHog’s integrations are free while Optimizely often requires a subscription to their data platform "enhancement."

PostHog’s data warehouse further expands these destinations by enabling you to use data from these sources directly in PostHog.

Privacy, admin, & security

Both PostHog and Optimizely have the privacy and compliance tools users expect.

Frequently asked questions

How difficult is it to implement Optimizely?

At its most simple, Optimizely’s web experimentation product requires adding a single script to your app. Their feature experimentation product is similarly simple, only requiring installing an SDK in your product and setting up the experiment logic.

To get full usage data and reporting, Optimizely also requires the implementation and connection of a third-party analytics tool like Google Analytics.

Optimizely’s other features are more complicated to set up, requiring a connection with your website, content system, or ecommerce software.

How difficult is it to implement PostHog?

You can access all of the features of PostHog, including feature flags and A/B testing, by installing a single script or SDK. There is no need to set up multiple scripts or SDKs for the different products.

Adding the specific logic for flags or A/B tests is as simple as a couple of lines of code. You can even implement them in no-code site builders like Webflow and Framer.

Who is PostHog useful for?

PostHog is useful for startups looking for all the tools they need to be a successful product. Companies like Y Combinator, AssemblyAI, and Contra use PostHog.

Who is Optimizely useful for?

Optimizely is useful for large enterprises looking to optimize their content, website, and ecommerce experiences. Companies like AmeriPride, JW Player, and HP use Optimizely.

Does Optimizely or PostHog offer a free trial?

PostHog offers a free forever plan as well as a generous free usage limit on the paid plan. This means you can access all of the features of PostHog for free as long as you stay under the free limits. It even provides billing warnings and limits to ensure you don’t go over the amount you want to spend.

Optimizely provides free trials for some of its products like feature flagging and content marketing, but most of its products (including web and feature experimentation) do not offer free trials.