> ## Documentation Index > Fetch the complete documentation index at: https://www.referly.so/docs/llms.txt > Use this file to discover all available pages before exploring further. # Tracking parameters > Reference for every Referly tracking parameter: referral parameters, rsubID external click ID, UTM parameters, gclid and other ad click IDs, cross-domain _plg_ref and _plg_cid, storage keys, and server-side attribution fields. Every parameter Referly reads, in one place, with the click field each one lands in. This is a lookup page — [URL parameters](/docs/developer-documentation/tracking/url-parameters) explains the behaviour behind it. Parameters fall into three groups. One identifies the affiliate and decides attribution. One enriches the click but never changes who gets credit. One carries attribution across a boundary the browser would otherwise break. ## Referral parameters The parameter carrying the affiliate's code. Your program uses exactly one, chosen from this fixed list, and `ref` is the default. ``` ref via partner aff id r invite plgid a stream mhk bt coupon promo with envoy plref refcode share s go partener virtual now vca offer am_id vap ooo freshbook img join referral_code fpr inv cpn trovabando fp_ref ``` | Read from | Stored as | Affects attribution | | ------------------------ | ----------------------------------------------------------------------- | ------------------- | | `window.location.search` | The click's `affiliateId` and `affiliateLinkId`, resolved from the code | Yes | Names are case-sensitive, and the value must be in the query string — anything after a `#` is invisible to the tracker. A link using a name on this list that is not the one your program is configured for is recognised as a candidate but resolves to nobody. ## Program identification The tracker needs to know which program it is running for before it reads anything else. | Source | Form | Notes | | ---------------- | ----------------- | -------------------------------------------------------------------------------------------------------- | | Script attribute | `data-program-id` | The normal way. Set it on the script tag. | | Query parameter | `programId` | Fallback, read from the URL when the attribute is absent. Useful on pages where you cannot edit the tag. | Without one of these the tracker exits immediately and records nothing. ## External click ID | Parameter | Click field | Sticky | | --------- | ------------ | ------ | | `rsubID` | `extClickId` | Yes | Your own identifier for the click, for reconciling Referly against an ad platform or a sub-affiliate network: ``` https://your-domain.com/?ref=jane&rsubID=newsletter-week-12 ``` It is stored in the browser for the same duration as the referral, so later visits without the parameter still carry it. A value on the current URL takes precedence over the stored one; when neither is present, the field is null. It is replayed to postbacks as `{extClickid}`. See [External click IDs](/docs/developer-documentation/tracking/external-click-ids). ## UTM parameters Captured verbatim from the query string when a click is recorded. They never affect attribution. | Parameter | Click field | | -------------- | ------------- | | `utm_source` | `utmSource` | | `utm_medium` | `utmMedium` | | `utm_campaign` | `utmCampaign` | | `utm_term` | `utmTerm` | | `utm_content` | `utmContent` | Each is indexed, so all five work as breakdown dimensions in analytics. ## Ad platform click IDs Also captured verbatim, and also irrelevant to attribution. | Parameter | Click field | Platform | | ----------- | ----------- | -------------------------- | | `gclid` | `gclid` | Google Ads | | `gbraid` | `gbraid` | Google Ads, iOS app-to-web | | `wbraid` | `wbraid` | Google Ads, web-to-app | | `fbclid` | `fbclid` | Meta | | `msclkid` | `msclkid` | Microsoft Ads | | `ttclid` | `ttclid` | TikTok | | `twclid` | `twclid` | X | | `li_fat_id` | `liFatId` | LinkedIn | `li_fat_id` is the only one whose stored field name differs from the parameter name. The presence of any of these classifies the click as paid traffic — `referrerType` is set to `paid` regardless of which domain referred the visit. See [UTMs and ad click IDs](/docs/developer-documentation/tracking/utm-and-ad-click-ids). ## Cross-domain handoff Written by Referly, not by you. Never add them by hand. | Parameter | Carries | Direction | | ---------- | ----------------------------- | ------------------------------------------- | | `_plg_ref` | The affiliate's referral code | Appended on the way out, read on the way in | | `_plg_cid` | The click ID | Appended on the way out, read on the way in | When a visitor with active attribution follows a link to a domain on your cross-tracking list, the tracker appends both. The receiving domain reads them, writes the attribution into its own storage, and strips them from the address bar with `history.replaceState`. They are also appended to form actions pointing at approved domains. See [Cross-domain tracking](/docs/developer-documentation/tracking/cross-domain-tracking). ## What the browser stores Three keys per program, each prefixed with your program ID. Cookies are used when available, with localStorage as the fallback when they are not. | Key | Holds | | ------------------------------- | ----------------------------- | | `PROGRAM_ID_affiliate_ref` | The affiliate's referral code | | `PROGRAM_ID_affiliate_referral` | The click ID | | `PROGRAM_ID_rsubID` | The external click ID | Cookies are written on the registrable domain, so attribution is shared across subdomains without any extra configuration. Details in [Cookies and storage](/docs/developer-documentation/tracking/cookies-and-storage). ## Values exposed on the page Once the tracker has resolved attribution it puts two values on `window` and fires an event. These are what you pass to your backend at checkout. | Global | Contains | Pass it as | | --------------------- | ----------------------------- | ----------------------------------------------------------- | | `window.affiliateRef` | The affiliate's referral code | `affiliateId` on a referral, or `referralId` on a sale | | `window.affiliateId` | The click ID, a number | `affiliateId` on a referral, for click-accurate attribution | ```js theme={null} window.addEventListener("affiliate_referral_ready", function () { console.log(window.affiliateRef); console.log(window.affiliateId); }); ``` See the [JavaScript API reference](/docs/developer-documentation/tracking/javascript-api/reference). ## Server-side attribution parameters When you report a conversion from your backend there is no URL to read, so you name the affiliate explicitly. These fields do the work the query parameters do in the browser. Creating a referral: | Field | Accepts | | ---------------- | --------------------------------------------------------------- | | `affiliateId` | An affiliate ID, a link slug, or a click ID | | `affiliateEmail` | The affiliate's email address | | `promoCode` | A promotional code, which resolves to the affiliate who owns it | One of the three is required. `affiliateId` is overloaded on purpose: a value made entirely of digits is looked up as a **click ID** first, which is why passing `window.affiliateId` straight through ties the conversion to the exact click that produced it. A non-numeric value is treated as an affiliate ID or a link slug. Creating a sale: | Field | Accepts | | ------------ | ---------------------------------------------------------------------- | | `referralId` | A referral ID, a link slug, or an affiliate ID | | `email` | The customer's email, matched against existing referrals | | `promoCode` | A promotional code, which credits its affiliate with no click required | One of the three is required here too. See [Reporting sales](/docs/developer-documentation/server-side/reporting-sales). ## Captured without a parameter Several click fields have no parameter behind them. They are derived from the request or the browser, so they are populated on every click whatever the URL looks like. | Click fields | Derived from | | -------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | | `documentReferrer`, `referrerDomain`, `referrerType` | `document.referrer`, then classified as `direct`, `search`, `social`, `email`, `paid`, or `unknown` | | `userAgent`, `browserName`, `browserVersion`, `osName`, `osVersion`, `deviceType` | The user agent string | | `screenWidth`, `screenHeight`, `colorDepth`, `pixelRatio`, `viewportWidth`, `viewportHeight` | `screen` and `window` | | `language`, `languages` | `navigator` | | `geoCountry`, `geoRegion`, `geoCity`, `geoIsp`, `isProxy`, `isVpn` | The IP address, enriched server-side | | `fullLandingUrl`, `pathname`, `queryString` | The landing URL, stored whole | `queryString` keeps the entire query string, so a parameter Referly does not read by name is still recoverable from the click. ## Precedence | Situation | Outcome | | ------------------------------------------ | ---------------------------------------------------------------- | | A referral code in the URL, nothing stored | New click recorded and stored | | The same code in the URL and in storage | Additional click recorded, `uniqueClick` false | | A different code in the URL | New click recorded; the stored code is replaced. Last click wins | | No recognised code, something stored | Stored attribution reused and its expiry extended | | No recognised code, nothing stored | The tracker exits without a network request | | `rsubID` in the URL and in storage | The URL value wins and replaces what was stored | | A cross-domain handoff and local storage | The handoff wins | ## Postbacks Postback URLs are the reverse direction — Referly filling parameters into a URL you own. The two that carry click identity are `{clickid}`, the Referly click ID, and `{extClickid}`, the value you sent as `rsubID`. The full macro list is in [Postback URL](/docs/developer-documentation/integrations/postback-url). ## Related How the referral parameter is matched, and how to change it. Every field stored on a click, with example values. The objects these fields belong to. Watch the tracker report which parameters it found.