How We Built This List and Our Ranking Criteria
Product analytics tools for SaaS fall into two broad categories: event-based analytics (PostHog, Mixpanel, Amplitude, Heap) and page-view-based analytics (Google Analytics, Plausible, Fathom). For SaaS MVPs, event-based analytics are almost always more useful. Knowing that a user visited your pricing page is less useful than knowing that a user triggered the "Start trial" event, reached the "Connected integration" event, and did not reach the "Created first project" event. We evaluated tools on six criteria. Event tracking implementation quality: how difficult is it to implement reliable event tracking, and how much engineering time does initial setup require? GDPR compliance: this is a genuine concern for UK and EU founders. Google Analytics 4 has been ruled non-compliant by several EU data protection authorities for transferring data to the US without adequate safeguards. PostHog (with EU cloud or self-hosted) and Fathom/Plausible are designed to be GDPR-compliant. Session replay quality: for debugging UX issues and understanding where users struggle, session replay is invaluable. Funnel and retention analysis: the two most important SaaS metrics to track at MVP stage. AI insight quality: several tools now offer AI-generated insights. We assessed whether these add genuine analytical value. Pricing at MVP scale: self-serve plans accessible to early-stage founders without enterprise negotiation.
The Full Ranked List: Pros, Cons, and Best For
1. PostHog. The best open-source product analytics platform. Includes event analytics, session replay, feature flags, A/B testing, and surveys in one tool. Can be self-hosted for full data control (excellent for GDPR) or used on PostHog Cloud with EU data residency. Free tier is genuinely generous. Best for: SaaS MVPs that want comprehensive product analytics without a multi-tool stack. Limitation: feature density can be overwhelming; more configuration than simpler tools. 2. Mixpanel. The gold standard for event-based product analytics. Excellent funnel, retention, and cohort analysis. Strong documentation. GDPR DPA available. Best for: SaaS products that need the deepest event analytics with the best funnel visualisation. Limitation: pricing at meaningful event volumes is significant; free tier is limited. 3. Amplitude. Product analytics with strong behavioural analytics and product intelligence. AI-generated insights (Amplitude AI) produce genuinely useful signals for product teams. GDPR DPA available. Best for: growth-stage SaaS companies needing advanced segmentation and AI-assisted insight. Limitation: expensive; better suited to post-product-market-fit than MVP stage. 4. Heap. Auto-capture analytics that tracks every user interaction without manual event instrumentation. Reduces engineering overhead of event tracking. Best for: founders who want analytics without intensive engineering setup. Limitation: auto-capture generates significant data noise; requires retroactive analysis rather than forward-planned events. 5. June. Product analytics specifically designed for B2B SaaS companies. Tracks company-level (not just user-level) metrics. Understands B2B concepts like company activation, expansion, and churn. Best for: B2B SaaS founders who need company-level product analytics. Limitation: less suited to B2C or consumer-facing SaaS products. 6. Plausible Analytics. Privacy-first web analytics. GDPR compliant by design. No cookies, no personal data. Simple and fast. EU-hosted. Best for: SaaS products that want web analytics without cookie consent requirements or GDPR complexity. Limitation: page-view-based only; not suitable as a primary product analytics tool for event-driven SaaS. 7. Fathom Analytics. Similar to Plausible: privacy-first, no cookies, GDPR compliant by design. Slightly different feature set. Best for: web analytics that requires no GDPR consent mechanism. Limitation: same product analytics limitations as Plausible. 8. Google Analytics 4. The most widely used web analytics tool. Free. Extremely powerful for web traffic analysis. Limitation: GDPR compliance for EU users is legally contested. Several EU DPAs have ruled GA4 transfers to US servers non-compliant with GDPR adequacy requirements. UK ICO has not issued a similar ruling, but the risk is real for UK companies with significant EU user bases. 9. Datadog (APM + user analytics). Infrastructure and application performance monitoring with user behaviour analytics features. Best for: SaaS products that want to combine technical performance monitoring with product analytics in one platform. Limitation: primarily an infrastructure tool; product analytics capabilities are less mature than dedicated tools. 10. Koala. Intent-based analytics that identifies which companies are engaging with your product or marketing. B2B SaaS specific. Best for: B2B SaaS products with a sales team that wants to know which prospect companies are actively using the product. Limitation: narrow use case; not a general product analytics replacement.
Comparison at a Glance
The most important choice on this list is between PostHog and Mixpanel for most SaaS MVPs. Both are excellent product analytics platforms. The deciding factor is typically: do you want the all-in-one platform (PostHog: analytics, session replay, feature flags, A/B testing, surveys) or the best-in-class event analytics (Mixpanel, which does event analytics better than anyone but requires separate tools for session replay and A/B testing)? For MVP stage specifically, PostHog's all-in-one approach is typically better value. At this stage, you need event tracking, session replay (to understand where users struggle), and feature flags (to run gradual rollouts). Getting all three in one tool reduces integration overhead and keeps your data in one place. GDPR is a genuine differentiator on this list. For UK SaaS companies with EU users, Google Analytics 4's legal status in EU markets is uncertain. PostHog with EU cloud or self-hosted is the clearest GDPR-safe option for EU-user-facing analytics. Plausible and Fathom are safe for web analytics. Mixpanel and Amplitude both provide GDPR DPAs and have EU data residency options, making them GDPR-compliant with appropriate configuration. AI-generated insights: only Amplitude's AI analytics produces consistently useful automated insights in our assessment. The AI features in other tools are largely surface-level anomaly detection with limited actionability. Do not choose a tool based on its AI insight features; choose it for the quality of its core event analytics and then assess whether the AI adds value.
How to Choose the Right Option for Your Situation
Define what questions you need to answer with analytics before choosing a tool. SaaS MVPs typically need answers to three types of questions: activation (what percentage of new sign-ups complete the key activation steps?), retention (do users come back after their first session?), and engagement (which features are used most and least?). All of the top tools on this list can answer these questions. The differentiators are: implementation effort, GDPR compliance, and cost. For implementation effort: Heap's auto-capture approach requires the least engineering time upfront but produces noisier data. PostHog, Mixpanel, and Amplitude require planned event taxonomy (what events to track and what properties to capture), which is a 4 to 8 hour design task before implementation begins. This event taxonomy work is worth doing carefully: well-defined events are the foundation of all future analysis. For GDPR: if you have EU users, use PostHog (EU cloud or self-hosted) or Mixpanel/Amplitude with explicit EU data residency configuration and a signed GDPR DPA. Do not use Google Analytics 4 as your primary product analytics tool if you have EU users, given the legal uncertainty. For cost at MVP scale: PostHog's free tier is the most generous on this list for event volume. Plausible is GBP 9 per month for web analytics. Mixpanel's free tier allows 20 million monthly events. The cost decision at MVP stage is less important than the product decision; choose the tool that answers the questions you need answered.
Our Recommendation
For most SaaS MVPs in 2025, PostHog is the default recommendation. The all-in-one nature (event analytics, session replay, feature flags, surveys), the generous free tier, the GDPR-compliant EU cloud option, and the open-source self-hosting option combine to make it the best fit for early-stage SaaS products. For B2B SaaS products specifically, combine PostHog for product analytics with June for company-level activation and expansion tracking. This gives you both user-level and account-level product intelligence. For web-only marketing analytics (not product analytics), Fathom or Plausible provide GDPR-safe alternatives to Google Analytics. SpeedMVPs implements PostHog as the standard analytics layer in SaaS MVP builds, with a planned event taxonomy defined during scoping so that you have meaningful analytics from day one of launch, not after two weeks of retrofitting. Get a free consultation at speedmvps.co.uk