An early SaaS wants three answers from its analytics, and it wants them for $0. Where did this week's signups come from? Which screen do they stall on inside the product? And which channels bring in the people who stick around long enough to pay?
Most founders get there by gluing free tools together: GA4 for traffic, Mixpanel or PostHog for the product, and something like ChartMogul for MRR. That works. You also end up with three logins and no easy way to join a payment back to the visit that started it.
This list covers eight tools, including ours. We make Spreelytics, so read our entry with that in mind. For every other tool we say what it does better than we do. Free plans were checked in November 2026 against each vendor's pricing page and docs, and plans change, so look again before you commit.
The short answer
If you want all three answers on one free plan, Spreelytics covers signups by source, funnels and retention, and revenue by channel with MRR, up to 1 million events a month. PostHog, Mixpanel and Amplitude do more inside the product, with feature flags, experiments and free session replay, but need a revenue tool beside them. For subscription metrics alone, ChartMogul is free up to $10K MRR and ProfitWell Metrics is free outright.
At a glance
| Tool | Where signups come from | Where they drop off | Revenue by channel and MRR | Free plan |
|---|---|---|---|---|
| Spreelytics | Sources, referrers, all 5 UTM fields | Funnels, retention, journeys | Both, on Free | 1M events a month |
| PostHog | Web analytics | Funnels, retention, paths | Attribution in beta | 1M events, 1 project |
| Mixpanel | UTM properties on events | Funnels, retention, flows | Attribution models on paid plans | 1M events, 5 saved reports per seat |
| Amplitude | Campaign reporting | Funnels, retention, paths | Not on Free's feature list | 2M events, 10 saved charts |
| Google Analytics 4 | Sources, campaigns, Google Ads | Explorations you build | Data-driven or last click, no MRR | Unlimited events |
| Microsoft Clarity | Not its focus | Session funnels, replays, heatmaps | No | Free, no traffic limit |
| ChartMogul | No | No | MRR, no channels | Up to $10K MRR |
| ProfitWell Metrics | No | No | Revenue dashboard, no channels | Free, no cap stated |
1. Spreelytics
One script tag collects traffic, sources, pages and all five UTM fields. The same events feed funnels of up to eight steps, retention for any segment you save, journeys, and a timeline for each person that starts at their first anonymous visit. So you can filter a signup funnel to people who came from Reddit and see where they quit.
Connect Stripe, Paddle, Polar or Lemon Squeezy and each payment is credited to the channel that brought the buyer, last-touch or linear, over a window you set between 1 and 90 days. A Revenue page shows MRR, ARR and refunds. All of it is on the Free plan, and nothing is sampled. New projects start cookieless. An MCP server lets Claude or Cursor read the numbers and build reports. SaaS analytics shows the whole setup for a subscription product.
Where others win: we have no feature flags, experiments or heatmaps, and session replay needs the Growth plan. Our Revenue page doesn't break out churn, upgrades or downgrades. Tracking is built for the web, with no native mobile SDKs, and we're closed source with no self-hosting.
Pricing: free up to 1 million events a month, forever, with unlimited projects, team members and dashboards and 13 months of data. Growth costs $59 a month at 1 million events. It adds session replay and the AI assistant, and keeps five years of data. Full ladder on the pricing page.
2. PostHog
Open-source product analytics that grew into session replay, feature flags, experiments, surveys and a data warehouse, all from one SDK. You can use its cloud or host it yourself. For an engineering-led team that ships behind flags and wants to measure each release in the same place, it's a strong default.
Web analytics is a newer part of PostHog. Revenue attribution is still in beta, with first or last touch.
Pricing: the free plan takes 1 million events a month in one project, with a year of data. Events past the million are dropped. Pay-as-you-go keeps the free million and charges per event after it. See PostHog pricing.
Choose it if you want analytics, replay and flags from one open-source vendor, and someone on the team is happy to build reports. Spreelytics vs PostHog
3. Mixpanel
Deep event analytics. Funnels, retention and flows are its home ground, and session replay, feature flags and experiments sit on every plan, Free included. It has native mobile SDKs and data regions in the US, the EU or India.
The free plan caps saved reports at five per seat and can't save cohorts. Revenue is data you send it yourself. Its nine attribution models start on paid plans, and its MRR and churn reports need billing data loaded through a warehouse. We walked through revenue tracking in Mixpanel step by step.
Pricing: free up to 1 million events a month, then per event on the Growth plan. See Mixpanel pricing.
Choose it if your questions are mostly about what people do after signup, on web and mobile. Spreelytics vs Mixpanel
4. Amplitude
The biggest free bundle here. Amplitude's free plan takes 2 million events a month and adds 10,000 session replays, feature flags, one live experiment and AI agents.
Free keeps ten saved charts for the whole organisation. Behavioural cohorts start on the paid Plus plan. Its pricing page lists no revenue or attribution reports for Free, although the product has ten attribution models, a data-driven one among them.
Pricing: 2 million events a month free. Plus is priced by volume, $720 a month at 10 million events billed monthly. See Amplitude pricing.
Choose it if you want the most product features at $0 and expect to stay under 2 million events. Spreelytics vs Amplitude
5. Google Analytics 4
Free at any volume, and almost everyone has used it. Its links to Google Ads and Search Console are first-party and deep, which counts for a lot if you buy Google traffic.
Funnels, paths and cohorts are explorations you build yourself, and an exploration switches to a sample once a query covers over 10 million events. Event-level data is kept for 2 months by default and 14 at most. Change that setting on day one. GA4 credits the key events and purchases you send it, by data-driven or last click, and has no MRR report.
Pricing: free, with no event limit. GA4 360 is sold through Google's sales team and has no public price. See is Google Analytics free?
Choose it if you run Google Ads, or traffic and sources are all you need for now. Spreelytics vs GA4
6. Microsoft Clarity
Session recordings and heatmaps, free, with no traffic limit. Watch a dozen people stall on your onboarding screen and the fix for that screen is often plain to see. Copilot sums up recordings in plain language.
Clarity's funnels count sessions, so a signup that spans two visits, say a Monday signup and a Tuesday activation, never completes. There's no retention report and no revenue by channel. Recordings are kept for 30 days, most other data for nine months.
Pricing: free.
Choose it if you want to see how people use a page, next to whichever tool counts them. Spreelytics vs Clarity
7. ChartMogul
Subscription analytics built on your billing system. It turns Stripe or Chargebee data into MRR and the other SaaS metrics investors ask about, with customer and revenue segments, and partner-built sources cover Paddle and Xero.
ChartMogul works from billing and lead data, with no tracking script on your site. Which channel brought a customer has to come from another tool, such as GA4 or Spreelytics.
Pricing: free up to $10K MRR, with one billing source. Starter begins at $69 a month billed monthly and rises with ARR, per ChartMogul's pricing page.
Choose it if you bill through Stripe or Chargebee and want clean subscription metrics for a board deck.
8. ProfitWell Metrics
ProfitWell is part of Paddle now. Its metrics product is still free, and it reads Stripe, Chargebee, Braintree, Zuora, Recurly or Paddle and builds a revenue dashboard from what it finds. Paddle's page states no revenue cap.
Like ChartMogul, it sees the money once it lands, and the visits that came before are invisible to it.
Pricing: free.
Choose it if you want subscription revenue numbers at no cost and at any size, from billing you already run.
How to choose
- One free tool for all three answers: Spreelytics, up to 1 million events a month.
- Flags, experiments and free replay matter most: PostHog, Mixpanel or Amplitude, with a revenue tool beside it.
- You buy Google Ads: keep GA4 for the Ads link and add a product tool next to it.
- You want to watch real sessions: Clarity, alongside anything else here.
- You only need subscription metrics: ChartMogul under $10K MRR, or ProfitWell Metrics.
If revenue by channel is the gap in your stack, how to see which channel earned each Stripe payment has the setup with code. For the product side alone, the best product analytics tools compares eleven of them.