The one most people mean by "there is a free one for Cloudflare". It is well made, it is genuinely free, and for what it sets out to do it is a good answer.
You would rather read the source than take a vendor's word for anything. That is a real reason and nothing below answers it. If what you actually want is pageviews, referrers and paths on a personal site, note that the free tier here covers the same ground without a CLI, does not sample, and upgrades in place if you ever need more.
It stores into Workers Analytics Engine, and Analytics Engine samples — by design, so that ingestion stays cheap at volume. That is fine for "was last month busy" and unusable the moment a number carries money: a sampled funnel is not a funnel, and a sampled revenue total is not a figure you can put in front of a finance team. It is not a bug to be fixed, it is the storage engine. Retention is 90 days unless you add the optional R2 export, and there are no goals, funnels, revenue, saved segments, alerts, or Google Analytics import — it never set out to have them.