The conversion rate optimization stack, tools and learning, in one place.
Most CRO lists are a vendor's own comparison page dressed up as a resource, or something nobody has touched since half the links went stale after an acquisition. I run experimentation for a living, so I kept my own.
Full-stack experimentation platforms, heatmaps and session replay, landing page and personalization tools, the self-hosted and open source options for when you don't want a vendor holding your test data, and the papers, books and communities that actually taught me something about running a test properly. Something only makes the cut if I'd genuinely reach for it or point a teammate to it.
🌿 means it's newer and still under 500 stars. Often worth a try, just less proven than the ones that have been around a while.
- Optimizely · Enterprise experimentation and feature management platform, one of the original A/B testing pioneers
- VWO · Full-stack conversion optimization platform combining A/B testing, behavioral analytics and personalization
- AB Tasty · European digital experience optimization platform for experimentation, personalization and feature management
- Convert · Privacy-focused A/B testing platform for mid-market and enterprise teams with transparent pricing
- Kameleoon · AI-powered experimentation and personalization platform for marketing and product teams
- Eppo · Warehouse-native experimentation and feature flagging platform, folding into Datadog Experiments after the acquisition
- Split · Feature flagging and experimentation platform built for developer workflows, now part of Harness
- Statsig · Experimentation platform bundling feature flags, A/B testing, product analytics and session replay
- Amplitude Experiment · Feature flagging and A/B testing tied directly to Amplitude's behavioral analytics
- LaunchDarkly · Feature management platform combining flagging, experimentation and release observability
- ConfigCat 🌿 · Developer-friendly feature flag service with a generous free tier
- Webtrends Optimize 🌿 · Web experimentation and personalization platform positioned as a VWO alternative
- UXtweak 🌿 · All-in-one user research and testing platform bundling usability testing with CRO tools
- Coframe 🌿 · AI platform that generates and continuously tests website variations to lift conversion without extra engineering work
- Humblytics 🌿 · Cookie-free A/B testing, heatmaps and Stripe-verified revenue attribution built for agencies and indie teams
- HeatMapX 🌿 · Developer-first heatmaps, A/B testing and on-site messaging with a Claude Code CLI for AI-driven fix patches
- Hell Yeah AI (Deja Vu) 🌿 · AI-native experimentation tool that generates and ships test variants automatically
- GrowthBook · Open source feature flagging and warehouse-native experimentation platform (MIT)
- Unleash · Open source feature flag platform with enterprise governance and self-hosting options (Apache 2.0), 10k+ GitHub stars
- Flagsmith · Open source feature flag and remote config platform with real-time updates (MIT)
- PostHog · Open source all-in-one product analytics, feature flags, A/B testing and session replay platform
- OpenFeature + flagd · CNCF vendor-neutral feature flagging standard, with flagd as its reference self-hosted flag daemon, so you're never locked to one experimentation backend
- Flaggio 🌿 · Self-hosted feature flag and A/B testing application with segments and percentage rollouts
- SwitchFeat 🌿 · Open source, self-hosted feature flags and A/B testing framework built in Node.js, TypeScript and React
- Bucketeer 🌿 · Self-hosted feature flag management and Bayesian A/B testing platform built by CyberAgent, supports progressive rollouts and OpenFeature
- FeatBit 🌿 · Open source feature flag and A/B testing platform with self-hosted and cloud options
- Flipt 🌿 · Open source feature flag platform that stores flags in Git, no database required
- Facet 🌿 · Self-hosted, cookieless web analytics and A/B experimentation platform that deploys to Cloudflare Workers with one command
- PlanOut · Facebook's archived library and DSL for designing online field experiments, no longer maintained but still referenced in academic and engineering writeups, ported to Java, JS, Julia and Ruby
- Wasabi · Intuit's open source enterprise A/B testing REST API platform, explicitly unmaintained per its own README but still usable and self-hostable
- slots 🌿 · Lightweight Python multi-armed bandit library (epsilon-greedy, softmax, UCB1, Bayesian bandit)
- PyBandits 🌿 · Python library for stochastic and contextual multi-armed bandits using Thompson Sampling
- SMPyBandits 🌿 · Research-grade Python library with 65+ single- and multi-player bandit algorithms for experimentation research
- StreamingBandit 🌿 · Self-hosted webserver for running and evaluating contextual multi-armed bandit experiments
- Hotjar · Heatmaps, session recordings and on-site surveys for understanding user behavior, now part of Contentsquare
- Microsoft Clarity · Free heatmap and session recording tool from Microsoft with unlimited usage
- FullStory · Digital experience analytics platform with session replay and behavioral data for product and UX teams
- Mouseflow · Session replay, heatmaps and form analytics with field-level drop-off tracking
- Contentsquare · Enterprise digital experience analytics platform combining heatmaps, session replay and journey analysis
- LogRocket · Session replay and frontend monitoring popular with engineering and product teams
- Smartlook · Session recordings, heatmaps and event tracking for websites and mobile apps
- Crazy Egg · One of the original heatmap and A/B testing tools, tracking scroll, click and confetti reports since 2005
- Plerdy 🌿 · Heatmaps, session replay, conversion funnels and SEO audit tools in one suite
- Matomo · Open source, privacy-focused web analytics platform with heatmaps and session recordings as add-ons
- Glassbox · Enterprise digital experience analytics with session replay and automatic PII masking
- Quantum Metric · Enterprise continuous product design platform with session replay and journey analytics
- UXCam 🌿 · Mobile-first session replay and analytics for iOS and Android apps
- Lucky Orange · Heatmaps, session recordings, surveys and live chat in one dashboard
- GeoTrack 🌿 · Session recordings, dynamic heatmaps and AI-driven visitor insights, plus A/B testing and Slack/email event alerts
- OpenReplay · Self-hosted session replay and product analytics suite, an open source alternative to FullStory/LogRocket with 12k+ GitHub stars
- WireQuery 🌿 · Full-stack session replay paired with backend API/network call exploration, includes its own query language and built-in PII masking
- NotJar 🌿 · Self-hosted, privacy-conscious heatmap and session-tracking alternative to Hotjar, very early stage
- Heatmap (ploi/heatmap) 🌿 · Open source Laravel/Filament click and movement heatmap tracker, flagged not-yet-production-ready by its own maintainers but genuinely usable
- Temps 🌿 · Self-hosted session replay bundled with analytics and error tracking in a single Rust binary
- Unbounce · Landing page builder with AI copywriting and Smart Traffic auto-optimization
- Instapage · Enterprise landing page platform with 1:1 ad-to-page personalization and built-in heatmaps
- Leadpages · Beginner-friendly landing page and lead generation builder with a broad template library
- Webflow · Visual web design platform for building fully custom, production-grade landing pages and sites
- Carrd · Simple, affordable builder for one-page sites and landing pages with a generous free tier
- Builder.io · Visual headless CMS and page builder with built-in experimentation and personalization for teams shipping on Next.js/React
- Webstudio 🌿 · Open source visual website builder and Webflow alternative that connects to any headless CMS, self-hostable
- GrapesJS · Open source drag-and-drop web builder framework for embedding a page/template editor into your own product, ~20k GitHub stars
- Silex 🌿 · Free, open source no-code website builder positioned as a Webflow alternative with full design freedom
- InstantLand 🌿 · Open source landing page and campaign builder with a GrapesJS visual editor, A/B testing and form/CRM integrations, can also clone existing site code into the editor
- Dynamic Yield · Mastercard-owned personalization platform for web, app and email experiences at enterprise scale
- Mutiny · AI-driven B2B website personalization platform that customizes copy and CTAs by visitor profile
- Webflow Optimize 🌿 · AI-driven landing page personalization, formerly Intellimize, now built directly into Webflow
- Insider · Omnichannel customer experience and personalization platform used as a Dynamic Yield alternative
- abmatic.ai 🌿 · AI-powered ABM website personalization tool positioned as a Mutiny alternative
- IntentFlow 🌿 · Plug-and-play AI widget that detects visitor intent and injects personalized hero-section variants in real time
- Apache Unomi · Apache Software Foundation open source customer data platform for real-time profiles and rule-based personalization, reference implementation of the OASIS Context Server standard
- Typeform · Conversational, one-question-at-a-time form and survey builder
- Qualaroo · Non-intrusive contextual "Nudge" surveys for on-site and in-app user research
- Sprig · In-product surveys linked to session replay clips for correlating feedback with behavior
- Survicate · On-site and in-product survey platform for continuous customer feedback collection
- Refiner 🌿 · In-app microsurvey tool built specifically for SaaS products with deep usage-based targeting
- Formbricks · Open source, self-hosted survey and in-app feedback platform (AGPLv3), unlimited responses when self-hosted, an alternative to Typeform/Qualtrics/Sprig
- Mopinion 🌿 · Feedback analytics platform for web, mobile and email surveys
- SurveyMonkey · Widely used standalone survey builder for market research and CSAT/NPS
- Pendo · Product experience platform combining in-app surveys, NPS and feature analytics
- OpenSurvey 🌿 · Self-hosted survey and experience-data platform with a visual builder, conditional logic and funnel drop-off analytics (MIT)
- Volet 🌿 · Extensible, embeddable customer feedback widget for Laravel applications
- TinyFeedback 🌿 · One-script open source feedback widget you can drop into any website
- Satismeter NPS Widget 🌿 · Embeddable Net Promoter Score survey widget from the Satismeter customer feedback platform
- OptinMonster · Popup and lead generation builder powering over a million websites, especially on WordPress
- Sleeknote 🌿 · On-site popup and lead generation campaigns for ecommerce brands
- Privy · Popup, email and SMS lead capture platform built primarily for Shopify and ecommerce brands
- Wisepops 🌿 · On-site popup and personalization builder positioned as an OptinMonster alternative
- OptiMonk · Popup, exit-intent and on-site personalization tool for ecommerce
- Poptin 🌿 · Popup and lead form builder with a generous free plan
- Convertful 🌿 · Opt-in form and popup builder with quiz and gamification widgets
- SuperPopups 🌿 · Lightweight popup and exit-intent builder aimed at small sites
- Nelio A/B Testing 🌿 · Native WordPress plugin for A/B testing, heatmaps and conversion optimization without external tools
- AB Split Test 🌿 · WordPress plugin for split testing blocks, pages, shortcodes and custom code entirely inside your own install
- Split Test for Elementor 🌿 · A/B testing plugin for Elementor that tests individual widgets or whole pages against each other
- PageFly · Shopify landing/product page builder with built-in A/B testing and heatmap preview
- Shoplift 🌿 · Shopify-native A/B testing app for product pages and checkout flows
- ConvertFlow · Funnel and landing page builder with personalization and A/B testing for Shopify and general web
- CXL · Conversion optimization training, agency and research institute widely cited across the CRO industry
- Baymard Institute · UX research institute benchmarking ecommerce sites against hundreds of usability guidelines
- Nielsen Norman Group · Longstanding UX research organization publishing usability and conversion-relevant studies for two decades
- GoodUI · Evidence-based UX and conversion pattern library built from ongoing A/B test research
- Growth.Design · Comic-style case studies breaking down growth and UX psychology behind product decisions
- Copyhackers · Conversion-focused copywriting blog and training, a CXL-adjacent staple for CRO writers
- Reforge · Practitioner-led growth and product marketing courses, the closest training alternative to CXL
- GrowthHackers · Long-running growth marketing community with an experiments and case-study library
- Mobbin · Searchable library of real app and web UI screens for conversion-pattern reference
- PageFlows 🌿 · Library of recorded user flows through real products for UX and conversion research
- Landingfolio 🌿 · Curated, searchable gallery of landing page designs and components
- Evan Miller's A/B Testing Tools · Widely-cited free calculators for sample size, t-test, chi-squared, Poisson and survival analysis in A/B tests
- ExP Platform (Ron Kohavi) · Ron Kohavi's hub of peer-reviewed experimentation papers, courses and rules of thumb from Microsoft/Airbnb-scale testing
- Trustworthy Online Controlled Experiments · Kohavi, Tang and Xu's practical guide to A/B testing at scale, considered the field's definitive text
- Statistical Methods in Online A/B Testing 🌿 · Georgi Georgiev's book on the statistics of continuous monitoring, sequential testing and risk management in A/B tests
- Peeking at A/B Tests · Optimizely's KDD 2017 paper on always-valid inference for continuously-monitored A/B tests, foundational for sequential testing
- YEAST: Yet Another Sequential Test 🌿 · 2024 paper proposing a new sequential testing method for online experimentation
- A/B Testing: A Systematic Literature Review 🌿 · 2023 survey paper mapping the academic literature on A/B testing methodology and practice
- Experiment Nation · Community, podcast, newsletter and Slack for CRO and experimentation practitioners founded by Rommil Santiago, also publishes the book Prove It or Lose It
- CRO.CAFE · Long-running multilingual podcast on conversion optimization hosted by CRO specialist Guido X Jansen
- MeasureCamp · Free community-run unconference series for digital analytics and CRO practitioners, held in 27+ cities
- Speero · Experimentation agency publishing XOS frameworks, benchmark reports, a newsletter and the EXL conference for CRO teams
- r/CRO 🌿 · Reddit community for practitioner discussion on conversion rate optimization
Last audited 2026-07-22 · 121 items · Submit an entry