How we count

These are definitions version 2026-10-05.1. When a definition changes, the version changes with it, so an old report can always be explained.

Headline metrics

The Humans filter means actor_class = 'browser': clients that look like browsers. An automated client that passes as a browser is counted here too.

A number that can't be computed, like sessions in aggregate mode, shows as unavailable with the reason, never as zero.

Channels

Evaluated in order, first match wins. The rules follow the default channel group of Google Analytics 4, mapped onto Little Friend's eight channels. utm_medium and utm_source are compared trimmed and lowercased. A referrer on the project's domain or any subdomain of it is internal: the view is not a landing, carries no source and counts no entry, and UTM tags on such a link are ignored. Channel and source are decided at ingest, so these rules apply to data received after they shipped, and older rows keep the channel they were given.

1. Paidutm_medium matches ^(.*cp.*|ppc|retargeting|paid.*)$ (cpc, cpm, paid_social), or is display, banner, expandable or interstitial
2. Emailutm_medium or utm_source contains email or newsletter, or is e-mail, e_mail or e mail; or the referrer is a webmail host (below)
3. AI assistantsreferrer is chatgpt.com, chat.openai.com, perplexity.ai, claude.ai, gemini.google.com, copilot.microsoft.com, you.com, phind.com (or a subdomain), or there is no referrer and utm_source names one of those hosts (assistants tag the links they show, for example utm_source=chatgpt.com)
4. Searchreferrer is a known search engine; or utm_medium is organic; or utm_source is google, bing, duckduckgo, yahoo, ecosia, brave, yandex, baidu or kagi, or a search engine's host (google.com). Search engine hosts: google.<tld> and google.<sld>.<cc> such as google.co.uk (other Google hosts are not search), bing.com, duckduckgo.com and ecosia.org with their subdomains, yahoo.com, yahoo.co.jp, search.yahoo.com and search.yahoo.co.jp with an optional country prefix (uk.search.yahoo.com), search.brave.com, yandex.ru, yandex.com, yandex.com.tr, yandex.kz, yandex.by, yandex.ua, ya.ru, baidu.com, m.baidu.com, kagi.com
5. Socialreferrer is a known social site; or utm_source is facebook, fb, instagram, ig, linkedin, x, twitter, reddit, youtube, tiktok, threads, bluesky, bsky, mastodon or pinterest, or a social site's host (facebook.com); or utm_medium is social, social-network, social-media, sm, social network or social media. Social hosts, each with its subdomains: x.com, twitter.com, t.co, facebook.com, fb.com, fb.me, instagram.com, linkedin.com, lnkd.in, reddit.com, redd.it, youtube.com, youtu.be, tiktok.com, pinterest.com, pin.it, threads.net, threads.com, bsky.app, news.ycombinator.com, the Mastodon hosts mastodon.social, mastodon.online, mas.to, mstdn.social, fosstodon.org, hachyderm.io, infosec.exchange, techhub.social, and any host starting with mastodon.
6. Referralutm_medium is referral, app or link
7. Campaignany other utm_source
8. Referralany other external referrer
9. Direct or unknownno referrer and no campaign. Labeled "Direct or unknown", because a browser often hides the referrer, so a visit with none may have come from a link

Webmail and email apps

Webmail hosts, each with its subdomains: mail.google.com, outlook.live.com, outlook.office.com, outlook.office365.com, mail.yahoo.com, mail.aol.com, mail.proton.me, app.fastmail.com, and Zoho Mail's regional hosts mail.zoho.com, mail.zoho.eu, mail.zoho.in, mail.zoho.com.au, mail.zoho.jp, mail.zoho.com.cn, mail.zoho.sa, mail.zoho.uk and mail.zohocloud.ca. Most email apps send no referrer, so a link in an email lands in Email when it carries a UTM tag such as utm_medium=email.

Chrome on Android reports a link opened from an app by the app's package name. A known app is stored as the web host its links come from, so the rules above apply.

Known limits

• UTM tags in the URL fragment (#utm_source=x) are not read. The script reads the query string only.
• Apps on iOS send no referrer. A link opened from an iOS app is Direct or unknown unless it carries UTM tags.
• An unknown Android app is stored under its package name, such as com.example.reader or com.example_reader, in Referral.
• The Swift SDK sends no referrer: iOS and macOS do not tell an app which app opened its link, so a link without UTM tags that opens an app lands as Direct or unknown.
• App events carry the device's time. On a device whose clock runs more than 10 minutes ahead, or more than 24 hours behind, the collector refuses them as clock_skew, and they are lost.
• An app sends its queued events with the app block of the version that sends them, so events queued before an app update are stored under the new version.
• A server goal that arrives before the app event carrying its correlation id counts as web, since no session holds that id yet. A flush right after the app event sends it at once.
• An app event keeps at most 8 properties: the SDKs read its keys in ascending order, since a native map has no order of its own, and keep the first 8 valid ones. A page keeps the first 8 in the order it wrote them.

Apps

An iOS, macOS or Android app sends to POST /v1/e with the same WireBatch as lf.js, plus one block, a, that names the app. A batch with that block is an app batch. A batch without it is a web batch, and nothing in this section changes for it.

Devices

An app's user agent is its HTTP library, so the collector reads the device from the app block and the families from its platform, never from the user agent. The actor class is always browser: a person using the app, counted under Humans.

Refused app batches

An app batch passes the same rate limits, quotas, clock window and event rules as any /v1/e batch. Allowed origins do not apply to it. These checks take their place, in this order. Each refusal is counted in rejects_daily under the browser source and shows on the data health strip.

Endpoints