Fathom Analytics vs PostHog
Both are analytics tools. Here is what separates them.
| Fathom Analytics | PostHog | |
|---|---|---|
| Category | Analytics | Analytics |
| Pricing model | paid | freemium |
| Price from | Paid | Freemium |
| Upvotes | 9 | 13 |
| What it does | Simple, private analytics on one screen you can read in ten seconds. | Product analytics, replays, flags and experiments in one open-source stack. |
What Fathom Analytics is
Fathom Analytics is a website analytics service that puts a whole site on a single dashboard page. That page covers pages, referrers, sources, devices, browsers, countries, events and UTMs. The script feeding it is 2 KB, served from cdn.usefathom.com, and goes in the page head carrying a data-site attribute with the site ID plus the defer attribute. It sets no cookies and states on that basis that no cookie banner is required. Compliance is claimed against GDPR, CCPA, ePrivacy law and PECR, and EU visitor data is routed through EU-located infrastructure. Traffic can be filtered before it is counted using IP blocking, country-level blocking and an allowed domains restriction. A dashboard can be shared privately, publicly, or behind a password. Fathom is a hosted service only and cannot be self-hosted. Events are recorded with a trackEvent call taking an event name and an optional value, and conversion rate can be calculated against total page views or against total people. Two constraints are worth knowing before naming anything: an event cannot be deleted or renamed once it has fired to a dashboard, and events need http or https to fire, so they will not track from a local file. Ecommerce tracking and event tracking carry no extra fee. The API sits at api.usefathom.com/v1 with sections for Account, Sites, Events, Milestones and Reports, and allows 600 requests per hour. Calls are metered against the monthly pageview allowance, so ten Create Site calls cost the same as ten pageviews. Integrations are published for WordPress, Vue, generic single page apps, SavvyCal and ConvertKit. Pricing starts at $15 per month after a seven day free trial, and the tier covering up to 500,000 pageviews per month is $45. Every plan includes at least 50 sites, and further sites are sold in packs of 50 at $10 per month or $100 per year. Paying yearly gives two months free. Historical data is kept for the full life of the account rather than expiring after a retention window, and historical Google Analytics 4 data can be imported. There is no contract, an account can be cancelled from settings at any time, and a full data export is available on cancellation. Fathom states it has never offered discounts and does not intend to.
What PostHog is
PostHog is a bundle of product tools that sit under one account, covering product analytics, web analytics, session replay, feature flags, experiments, surveys, error tracking, logs, LLM observability, a managed data warehouse and a customer data platform. Analytics starts with autocapture, which records pageviews, clicks and form submissions without per event tracking code being written first. On top of that sit funnels, retention curves, path analysis, trends, dashboards and direct SQL querying for the questions the built-in views do not answer. Incoming events can be transformed before they are stored, including IP anonymisation and hashing of personal data. Session replay has SDKs for web, React Native, iOS, Android and Flutter. Recordings can be sampled, or gated by URL or by feature flag, so that only chosen sessions are captured, and text, inputs or whole elements can be masked on the device before a recording is sent. Retention runs to 30 days on the free plan, 90 days on pay as you go, one year on Boost and Scale, and five years on Enterprise. One detail catches people out: changing the retention setting applies only to recordings captured after the change, because existing recordings keep the period they were captured under. Feature flags support percentage rollouts, targeting by individual user or by group, multivariate variants and JSON payloads. The free tier is metered monthly. It covers one million analytics events, one million feature flag requests, 5,000 session recordings, one million data warehouse rows, 10 GB of ingested logs, 100,000 tracked exceptions and 1,500 survey responses. Usage past those allowances is charged per unit, starting at 0.00005 USD per analytics event, 0.0001 USD per feature flag request, 0.0050 USD per session recording, 0.000015 USD per data warehouse row and 0.10 USD per survey response. An account with no card on file is limited to one project and one year of data retention. Adding a card raises that to six projects, seven years of data retention and email support. PostHog Cloud is offered in a United States region and a European region hosted in Frankfurt. Public event capture endpoints live at us.i.posthog.com and eu.i.posthog.com, with private management endpoints at us.posthog.com and eu.posthog.com. The API accepts personal API keys, project secret API keys and OAuth, and the public POST-only endpoints are not rate limited. Self-hosting is possible but limited. The Docker Compose deployment is released under the MIT licence and wants roughly 4 vCPU, 16 GB of RAM and more than 30 GB of storage running Ubuntu Linux, but it is officially unsupported and carries no guarantees. Paid plan features are available only on PostHog Cloud, so a self-hosted instance runs the free feature set.
We are not affiliated with either product. Upvote counts come from the published formula and neither position was paid for.